my 2.5..will she or wont she?

for those that have followed my build i now have my car near run in ,
i have to say it sounds awesome and but for the slimline fan not being able to regulate the temp quickly enough for my liking it's running flawlessly

untill i sort out another solution we have had to remove the aircon rad and move everything as far forward as possible and squeeze the originals in... which are working a treat for now, though i expect that wont last as they are 2 millimeters away from the turbo and touching the manifold at 1 point i think ,so i don't hold out much hope for the bearings when i start boosting the turbo untill its glowing!

the car is unmapped and on a gtec chip yet we have seen 1/2 a bar at 3k! already and i have had to drive with a very light foot and let revs build gently...i don't like the thought of my turbo bearings and that crappy mineral oil!

i go on tuesday to have a dta ecu wired in and over the week get it mapped though we can only go to about 550 as the rollers can not cope with much more and i will have to go back a few weeks later as john(mapper) is having new rollers for upto 1000 bhp installed

i am so impressed and glad that the car has been so easy to get on with and not given any problems at all for which i have to say a big thanks to barbz who is just an incredible and enthusiatic tuner/engineer/engine builder as some of the solutions he has come up with for various problems we came up against are just brilliant and i believe completely that very few people could have built a set up as good as this..

it's not just about forging internals and bolting on a big turbo..some of the over seas guys have done that and we have seen there power graphs...not a lot happening at all then it all happens over a few thousand revs..no problem with that if thats what you want but to build an engine thats so civilised and easy to use and yet will out perform most supercars for a fraction of the cost is no mean feat..i may be jumping the gun here as i am yet to be mapped and the mappers skill will come into play also,but from the performance so far and from driving barbz which is similar upto a point ,i am sure it will do what i asked him for..and you have to respect the guy that designed and built it as he went with a new piston design and everything from the headwork to head/valve design,manifold diameter pipework etc were all designed to make the type of engine i required..this was not just some buy everything off the shelf and fit together job but a proffesional aproach to a cohesive whole he was trying to achieve and has done so exceptionally well..just brilliant

i wanted a car i could drive everyday that was good and easy in traffic smooth to drive if i was running round with the wife and kids yet brutal enough to beat every coupe in the uk if i wanted to ( i also said i would like to see 600bhp without race fuel)but that wasn't first priority ..seriously thats what i asked him for! and it is real smooth and real easy to drive in fact the hardest thing about it is the clutch which although is no major issue is quite "well sprung" shall we say

so i have everything i wanted, the final ask will not be known for a while though, as i say johns rollers may not be able to cope but will she or wont she?

for those thinking of doing similar i will say this if you are not going to use the extra 100 bhp don't do it!.. its pretty straight forward to do a 500 bhp 2.4 as you can use the standard manifold though it will need barbz to work on it for that ..and you can use standard garret turbos even internal wastegate so its all straight forward stuff..the amount of extra money it costs to take it to over 600 and have a clutch and other parts that can cope is not at all in proportion to the extra gains

theres also a lot of extra work in trying to get a much bigger manifold,a turbo twice the size of the original and air cooled,an external gate,plumbing for it all to fit and not to cause massive issues with heat etc(especially when a awkward owner wants to keep his aircon..i wont even start on the things that have gone into the build that have never been (or needed to be) on other coupes it really does have a lot of 1 off and original parts and solutions.

all in all i couldn't be happier with the car and am looking forward to seeing what it can do

Rob that sounds like quite a revolutionary project you and Barbz have achieved, can't wait to see and hear it in action someday soon - fair play, i bet this wasn't a cheap option either

I've seen your car many times(while in bits) at Barbz, and I must say, it will be fascinating to see what you can get out of it.

Look forward to seeing the results, but would love to see some pics of the engine bay with how everything is all fitted together

All im saying is i hope it goes alot smoother than mine mate and you have no teething issues.

Also i suggest you fit that big brake kit asap.

proccy..hi mate sorry about your car ..i saw it myself and really feel for you its such a nice one it would have been a shame to do anything but fix it and fair play to you for that..good luck with it all


when i decided to go 2.4 i was thinking that if i was going to put serious money into building one i wanted to build something special rather than another 450 or so which is achievable for reasonable money now its a well trodden path so to speak..
luckily i spoke to barbz about it first and he had the enthusiasm for this and once we started talking about possibilities that was it! we spent 2 and 3 hours a night on the phone for weeks working it out and sorting/sourcing it all etc and at that point it seemed like we would do a good 2.4 at the same money a 450 2l would cost as thats quite easy..!..

unfortunately or fortunately depending on whether you think financially or strictly of the car!... as time went by i found all sorts of things out and discovered all sorts of parts on the internet and just couldn't help myself..
at that point budget went out of the window and it was about buying the best i could afford..i got the best turbo i could find though barbz had to temper me to the version i have now as i was going for the model above which can give 800bhp(would have thrown up even more issues that would need solving) same with manifold,wastegate etc..it became obvious we could only make so much power usable so that dictated engine spec to some degree..
again with the rest of the car i thought it pointless putting such a motor in a chassis that wasn't capable of exploiting it so i set about that in the same way and although i had accumulated masses of parts the only bit i used was the aquamist! so suspension i decided to go new so as to get it to handle well ...arbs,brakes,bushes,etc followed as i thought i would make it as good as i could
finally when barbz fitted the motor to jamies old green coupe i decided i would go on a mission to find a nicer one..my thinking was after spending all that money do i want a standard green(my least favourite colour) car? the answer to that came 1/2 dozen coupes later in my ink black plus which has a real solid chasis and good bodywork ..i am now making it lighter with new lightwieght seats(though they have to be recliners for getting kids in),hopefully grp bonnet(second hand) and other mods to lighten it..

all in because of the route i took and the spec i went for, including car itself and including my mapping next week...£15k i think i have not had the nads yet to add it all up

i have to say this though ..again as a testament to barbz.. if i had been charged by the hour it would have been £50k! seriously barbz has spent so much time and trouble on this project, over and above that agreed, it's not fair! and i mean it's genuinely not fair on him..
he costed a build that was simple and with some hours to be spent on the chasis also..it turns out to have been massively under priced ..heres an example..to get a clutch to cope and not need replacing quickly, he had to develop in conjunction with helix, a clutch which was to be the highest rated,biggest surface area unit so far ..that on its own meant fitting, refitting,sending bits off to be machined,bits back to helix..fit again, measure,send back etc etc..the whole project has been a bit like it..he has also built the car once then stripped and transferred the lot to another chassis..but its the late nights finding solutions..making brackets,taking stuff to be made or re engineered,fitting ,removing adjusting then refitting as everything is none standard and nothing would have fitted had he just tried to use the standard set up..
he really has been a complete star and would not take more than the estimate he gave as he knew i had over specced it and could not afford the spec i bought never mind a massive bill from him so he decided to do it to the best of his ability for the sake of the car and our new friendship..lets be honest who else would have done that? (though johnny bravo has helped me also above and beyond) obviously i owe barbz big time and i will have to deal with that over time but like me he just wanted to see what we could achieve with the spec i bought and was still as enthusiastic about it at the end though he wasn't getting paid anywhere near his lowest rate!
so it wouldn't be running at all but for his generosity with his time..

hope it bloody lives up to our expectations after all this!

ill get some pics up soon nigel

Sounds like a great car Rob. Fair play and good luck with it.

thanks it does need your input though patch to make it as nice as it can be so if you have the time and inclination next time you are over?

Wow you told me it was going to be special and Barbz was THE man but he sounds like he's made you a super car slayer.

Good luck with the mapping, hope its as useable as you want and not nothing nothing here comes the boost 650bhp change gear like the other big turbo jobbys I know yours wont be that.

Reading all that makes me even more glad I stayed strong and didn't sell you my Black Le because if I knew that engine was in what would feel like MY car it would have made my insanely jelous.

Get the pics up AND a vid and are you going to get it to pod this summer?

No problem Rob, it's about time we met face to face. We'll chat when I'm back

Rob,is it ok for me and possably scal_LE33(red plus ;)) to pop in at JDM for a peep? Have you seen his new rollers!? they are MASSIVE

Dave

All sounds amazing, respect to Barbz and yourself.

As far as i'm concerned your welcome to come and see what it does and have a nose round the car, i'll be up tuesday but i would imagine he'll just be wiring it in...i should think thursday/friday will probably be the days when she's actually on the rollers!

I was tempted to wait until his new rollers went in but its no good driving her unmapped so we'll just go as far as we can with the set up he has at the minute...when John first started his tunning i believe that there were very few cars that could max his rollers out!

Oh and John as soon as you've got a sspace mate...brakes and maybe get the seats and harnesses in...

one last thing about the car...the gear shift is just sublime its nothing like a coupe at all anymore..i don't want to keep banging on about barbz like some brown nosed sychophant but again this is another example of the way he works ..spending hours and hours just to get the gear shift perfect with the type of car it is and the way its going to be used...he had an idea in mind for a proper slick shift and again for no extra cost and just for the sake of doing it right he had some unheard of metal bits made up along with other mods and has created by far the best shift of any car i've yet driven. its a mod i would recomend to anyone

get a gearbox cooler pal, i think you'll need it

yes mate i am looking at options there and already have a spare box waiting! but thats another thing needs doing as i can afford it..build a gearbox to compliment the car that is

good to hear its going so well ktm cant wait to see it on the move

glad to hear its finally on the move rob.

when your ready, can you post up a full spec list for us all to drool over?
carnt wait for the results.

Good work Rob can't wait see it.

Well it all sounds very interesting, I know first hand how a project like this can be so demanding. Is there not a project thread I can read ? I could only find this - Thread

Rob, I asked for pics, not Nigel

Cool stuff indeed ktm..

Saw the new inky plus during the engine transfer stage and it looked better then green one, by miles.

However JBT's black coop looked like one mean assassin..

I would say lets see what the actual figures are before we jump to any conclusions..Whatever the outcome its all about how YOU feel about it, that's my opinion on it.

Lastly, whats with the new friendship,or is it more ahhhem

"so he decided to do it to the best of his ability for the sake of the car and our new friendship."

tricky sorry about that! i binned that one it was probably not a good idea using mostly second hand parts and trying to do it for very little,though it was possible..
there will be a full spec list when its mapped and we have some figures and graphs..
as a written project to distill the last eight months and all the little and large issues into a readable thing is too daunting a task at the minute as i am so busy but we will do some sort of outline with pics at some point

sorry begbie i must have been tired!

nazo..do you have to?
what i meant by that was..you can't help but become friends when you are doing something like this and both have the same enthusiasm for it..it was not the same situation as taking it to a garage and saying right do this and getting a bill...we spent a lot of time working it out and discussing it ..he is a genuinely nice guy and an honest and generous one.. which was refreshing and i couldn't be anything but friendly with someone with such a good spirit and he did a lot of the work out of that generosity of spirit rather than trying to extract all the financial gain he could from the situation, as is the case with some of the specialists and garages i have come across...
hope you can see what i mean

we're not talking "friendship" as in are we Rob?

ok i give up... where do i get the purple jumper? any room for more gaymigos?

ok i give up... where do i get the purple jumper? any room for more gaymigos?

a little update...i have blown the first box in the exhaust at the seams and thats without going over 3.5k revs and 1/2 bar boost so am now looking into options on the boxes as who knows what will happen at 7700 rpm and 1.6 bar

You mean exhaust box?
How many of them do you have?

2 as i had to have the first one a distance from the manifold as its ceramic coated inside and out and will be transferring a lot of heat..we had stainless wool in the first as wadding would likely just burn up..they are large silencers though..i am thinking of a race cat as it may be a help with dissipitating the heat..thats probably the wrong word as its covection i think with heat but you know what i mean

I would remove the first one and left just the rear one!
Becouse heat would exit much faster and cool much faster till it gets to rear silencer!
Wich diameter of piping are you using?

3" all the way from the turbo

good luck Rob...

thanks carlos how are you getting on with yours?

for now everything is fine, just have to do many hours of road,and I have to go up because it is really very low,tomorow hehehe...I"m realy happy...

What Carlos means is that he needs to set the coilovers to higher ride heigt cause the car is really low at the moment...

just trying to help...

Called in today but i was too early as there was just a 127bhp mini on his rollers I`l try pop in on thursday to see the Beast.

Dave

glad your happy with it..
we will be running it up thursday, not much happening tomorrow just the wiring but barbz, rob, john and i will be there on thursday for the mapping...had my exhaust repaired today as well...i'd blown a 6" long split/flap in the first silencer...all i can say is that its a good job its a lifetime guarrantee as i'd done that on 1/2 a bar of boost...i'll post thursday night with what happens on the day

Good luck Rob - see her in the flesh soon?

for sure i will be attending various events in her

Dependant on circumstances outwith my control, I may also pop in tomorrow mate... probably with barbz!!

Ross

why not the more the merrier

Hope all go,s well tommorrow rob


paul.

Any news, Did she or didn't she?

she didn't!
just to quash some of the rumours ( i heard about my own car!) she blew bits of exhaust out then the first box was just hollow (causing all sorts of turbulence etc) so we removed it and gained 50bhp straight away..the down pipe is too restrictive which is making the manifold glow very quickly so as is often the case with new territory it's back to the drawing board..we think the external gate pipework is too short and coming into the down pipe at too great an angle so the gasses are setting up serious turbulence/resonance causing the gasses from the manifold to back up.. you can hear it, compared to robs it sounds choked and as i say even though the manifold is ceramic coated inside and out it glows very quickly..even so we made just over 300 at 1 bar where robs makes 40 or so more at the same point.. and we made nearly as much torque which is a suprise..we turned the boost up and saw 360 but it was obvious we had issues so left it before doing harm... we will cut the external gate pipe away from the down pipe and see what happens with a screamer next..
i will share the fortunes and misfortunes now as so many people are asking whats been going on..
our biggest problem is space and heat as the turbo and manifold are so big as well as the wastegate and its plumbing it's all pretty cramped and theres a lot of very hot things in a small space so i am considering venting the bonnet to let it out (no silly scoops!)
luckily our exhaust guy is very good and is eager to find a solution..he didn't have many options with our serious lack of space so now we have tried the simplest solution, he will try another aproach (free of charge thankfully)

the main thing though is the engine itself runs very nicely..it's quite,starts straight away evrytime and idles well,even though they get warm on the dyno the oil pressure never dipped below 2.5 bar so when we get the bolt on bits sorted i am confident it will be as good as i hope

just take your TIME, don't expect 500hp in an instant, won't happen.

It took me a long long time to get to just 440hp & even though I can now surpass this, I'm happy to leave be, just ensure you have a driveable lump & that the power range is a broad a possible pal.

With some tweaking, you'll see your goal, but just accept it takes time & refinement, as it's ALSO VERY easy to ruin all that work in a few secs on a dyno.

Good luck & stay +ve.

good luck mate, and take it easy!;-)

for those still interested ..we removed the down pipe and cut the external gate pipework away from the down pipe and again we gained near 50bhp which has taken us over 400bhp so we have gained over 100bhp from removing restrictions from the hot side but still it's not giving all it can by a long shot it seems we have some sort of restriction still which can only be the manifold itself..
now having spent well over £1200 on it then another £200 ceramic coating inside and out i am going to be mighty upset if it is as we suspect the culprit...
i am no exhaust guru so i hope someone with knowledge can chip in here as i was told the manifold was good for over 600bhp by the (very well thought of in the tuning world) manufacturer..i told them i was doing a 2.4 so would have expected them to tell me if there was any possible issues..
on contacting them they say it makes no difference it will flow over 600 with 5x36ml internal diameter primaries..
to me that does not sound right as the 2.5 (which mine is) is a long stroke engine so the pulses will be different as will the shear amount of gasses flowing..
rob had a 2871r on his 2.4 and it gave positive boost just off idle and was on full boost by 2800 revs..it then choked up at 5500 i think and it didn't want to rev on (sorry if i am a little inaccurate rob but its about right)..the point being the same turbo on a 2.0l is not on full boost untill 4k+ and will rev out not choking up at all..to my mind(limited knowledge accepted) thats down to shear amount of gasses..if this is the case then what makes 600+ for a 2.ol would likely not for a 2.5..
can anyone confirm this?

my next move is to have one custom made in italy to my own spec..
here though i have a problem in so much as i am not sure what size primaries to order as too small and i wont make the power,too big i lose all bottom end..though i don't think its anywhere near as much as with an n/a..the manufacurer thinks 38 should do but with 36 only making 407 i am dubious and think maybe 40 at least it will definately make the power..the new design type has longer ones also
will be interested to hear opinions on this

what manifold did johnS use then because he was running 550+ on the 2.4 design lump?

empty your pm's aswell ktm

Why not take it of and have it flow tested?

john used one from scara with he thinks only 35mm id which is the standard one they sell but if thats so it can only be that it used longer tubes with less tight bends as its actually smaller though a completely different design

Ever thought of running a 4" downpipe and exhaust system?

its probably not worth 4" as the vband on the turbo is 2.5 as the turbo itself is only 2.5 on the hot side(they are all like that) but it goes straight to 3".. i am considering a 3.5 downpipe though..we are removing the aircon and redesigning exhaust

well, at least you have managed 400bhp with out hardly any effort Rob!

good on you!

what boost did it hit 400bhp at?

really sounds like you have a nightmare with the exhaust set up.

a 3.5" sounds like it will free it up a bit more... its going to be a long trial and error game now mate!

stick with it mate! your not far from the finish line

You need to measure your EGTs to work out where the restriction is

My guess is that its the 2.5" V-Band - 5-stud flange would be less restrictive

thats what we thought but the turbos come like that with a 2.5" outlet and they are hapily making over 600 on other strokers ..we are external gate so don't need a 5 stud bet we thought 3" would have been better

Have you changed the manifold yet rob? Or are you still trying to source one?

Ross

trying to source but its a minefield of contrary information..all we can say for certain is that john s worked so i will try one ..though funny thing is the primaries on his were smaller than mine..go figure because i can't!

Have you managed to get yours flow tested yet?

Ross

rule of thumb from what ive been told is 1 and a 1/2 times the size of the turbo hotside is the best for a down pipe and the closer you can make it near the turbo outlet the better.

is that 1.5 times size of turbo outlet? and do you mean it needs to reach that size as near outlet as possible?

ross flow testing i am not sure what that can tell us about the differences in flow capability between the cars but i would get it checked if there was someone near i knew could do it

i am not sure if a 3.5" downpipe would make a diference..the biggest pproblem is room and having to use such tight bends straight out of the turbo i am wondering if there is anything else i can do about making space for the downpipe to be able to run straight outwards a little further

Isn't there an alternative route you can takE?

Ross

carry on!

1.5 x the size of the turbo hot side ie the outlet and the faster you can get to that diameter the better so either straight away if room or when ever your able to

ok we were straight to 3" but i will go for a 3.5 and see what that can do as after gaining over 100bhp removing bits of exhaust i want it as free flowing as possible

Italy for a manifold? would you not consider booking it in to OJZ or Simpson racing exhausts with the planned sizes you want and leave the rest up to them?

ojz has a 2 month + lead time i have not tried simson but will look into it tomorrow..thanks

Have you called OJZ though? He might have a shorter lead time now that the racing season is underway

have spoken to him today to be frank he was suprised the 36ml primaries were an issue

Three things:

1) 600 BHP will produce the same amount of exhaust gasses, whether produced by a 2 litre, 2.5 litre or 5 litre engine. That is because you will be burning the same amount of fuel in the same amount of air in the same amount of time in order to do so.

2) a five cylinder engine will not be choked by 36mm ID primaries at 600 BHP.

3) increasing the diameter of the pipe to a diameter much larger than the oulet from the turbo (in your case 2.5") will not yield much benefit.

In an earlier post you did alude to the fact that there are 500-600bhp engines producing big power without massive pipes after the turbo. Another clue is to look at turbo race/rally engines. Lancia, Porsche, Ford, Audi - never mind the F1 teams in the turbo era - ran with pipes no larger than the turbo exit diameter. Think about it: the biggest restriction in the exhaust system is is the smaller diameter (exducer diameter) of the turbine wheel itself.

Of course the frame size of the turbine housings are limiting - a GT28 will not flow as much exhaust gas as a as a GT30

ok i had thought that myself (no point bigger than 2.5)but having gained 50bhp by removing the centre exhaust section ,then another 50 nearly venting wastegate to atmos rather than down pipe i am leaning toward giving it as much space as possible..it would run best just turbo with no exhaust so to my thinking ;the least restriction and the more ability to flow the better? yes no? this is bloody hard work for the layman..
i spoke to the american turbo supplier and they said give it as much room as possible as it will give its best with no exhaust!

what were the lancia,f1 etc doing with thiers? using outlet size for downpipe?

The facts are 2 identical cars to yours are running well,Barbz,ROb40.The only thing you have different is the manifold and blower,.
The only concern is that Johns ran smaller primaries than you currently have.
That said,Johns build does differ from yours quite a bit.

The complications involved in calculating the flow and pulse rates of this is based on theory mainly over forums.
But i know full well that a manifold can cause more issues than the stock one.

Stick with it mate and dont spend all night worrying.
The best man is on the case and im confident he will sort it.

Ditto!!!
I cannot believe that your 36ID manifold is the cause for this issue…
Johns had 34mm ID – this will result in a better response in lower revs, but your manifold definitely should be better in top end performance.
As I stated to you – I have 34ID as well (I bought mine from Cufaro Racing some years ago, it was selfmade from Cufaro – no Italian like Scara) – after about 560HP there was no chance to get more HP out of my GT3082R – either it was my manifold or it was my small 0,64AR.
We will see after installation of my new GTX3582R – this unit is capable to do 760HP. Thus this new charger definitely won’t be a limiting factor. Then I can tell you how far 34ID will reach…
Other suggestions:
- Check your catalyst (do you have one?)
- maybe your coating reduced the inner diameter of your manifold in some area significantly – check with an endoscope?!
- Check of the charger – is it ok? Maybe that a small 0,63AR had been installed instead of your wanted 0,82?
In my opinion you bought the best available manifold on market for this car. Moreover the 3” downpipe is more than sufficient.
There must be another reason for this issue…
Juergen

Are you using one of Leighton's big MAFs?

no maf i am on a dta standalone nigel

i also think its got to be something else as the more i look into a solution and the more manifold specialists i speak to i find 36 should do it easily..
however i also find that primary length has a big effect as does collector as does angle of wastegate pipe exit and cubic capacity should have a direct relationship on the length of the primaries
so i also know you cant just knock one up and expect it to work well
the feeling at the dyno was it was a restriction and the more we removed from the hot side the greater the bhp which i know was inevitable but not to the degree we experienced..there is still no easy explanation for why however much boost we gave it it couldn't get much further than 400bhp and all we got was quicker glowing of the manifold which again is indicative of restriction..we were holding steady boost also
we are going over every valve,the whole boost set up and testing wastegate etc also so maybe we will find something..i hope so as it will be an expensive fix otherwise!

Obviously restrictions futher down the length of the exhaust will cause flow problems, so removing one of them (as you have ) will bring improvements.

Venting the wastegate to atmosphere is a very good thing to do, because dumping a big volume of high temperature gas into the flow directly after the turbine exit will reduce the pressure difference across the turbine and increase the volume of exhaust gas that the pipe has to flow (hotter exhaust gasses=greater volume).

If you can remove further restrictions in the exhaust after you 3" pipe you should see a benefit, but if you go up in size from 3" to 3.5" any benefits will be negligable.

Yes, in all the pictures I have taken they use the same size pipe as the turbo exit/outlet. Pictures I took at Goodwood Festival of Speed 2009 included Lancia LC2, Ford RS200, Audi Quattro S2, Porsche 956, Bentley Speed 8, Audi Le Mans petrol engined winner - same engine as the Bentley of course. F1 pictures are not mine but from the book 'Formula 1 - the Turbo Era'

You should expect the manifold to glow red/orange - EGTs will be 800-900 degrees C at load on boost. Seeing the manifold glow is not a sign of a restriction. Whatever the setup, at high boost pressures the pressure in the manifold is going to be equal or greater than boost pressure even on a perfectly designed system.

What turbo is it you are running (I've read the thread through and couldn't find this information)? I am particularly interested in the turbine spec and housing A/R so I can do some rough calculations.

i will send spec via pm but what i meant by the glowing was that it happened much quicker with more boost even though we made no power

whats Barbz's theroy on this?

It looks like your 'hot side' is what was run in the racing version of the Ford RS500 (rather than the road car which was a bit smaller) - a T31 housing with a stage 3 turbine.

If so, the turbo should not be causing a restriction up to similar power figures - though who knows beyond that?

what do you think of it? it is pulling hard by 3200 and ive seen positive boost at 2500 when booting it and thats with the .82..
marco..the mapper said he has seen similar a number of times and he was sure it was restriction on the hot side which seemed to be right as we were removing bits it was bearing out what he thought
however barbz thinks that before we bin the manifold we go over everything for boost leaks or duff valves then if no better we try another manifold and turbo to see if the set up gives what it should with that..
if not its not manifold/turbo..
if it gives what it should then it is ...simpless!
so those are our next steps...ill post the results

any more news on the restriction KTM?

yes ..after testing it turns out as we suspected to be the manifold
..although it flows very well with a 2.ol it does not for the 2.5..with the size of my comp wheel and valves this manifold just does not deal with it efficiently..we have longer pulses with greater volume of gas than the 2l with its shorter stroke and less cubic capacity...
just goes to show what works well on one set up does not on another
we have gone with a bit of a radical idea for a solution...something definately as yet untried on any coop anywhere..i can't actually find information on any car (as yet) thats tried it as a tuning solution though there are one or two older turbo cars that used it though not at our power level
the sad thing about it is it was so well made..a real nice piece of kit...someone with a 2l will make over 500 with it though i hope..the other loss is that we had full boost by 3200 revs on a 600+ capable turbo...the company themselves have been very good and offered to build one to any spec from a full race manifold with turbo position moved to similar with bigger id, free of charge.. but we are going as i mentioned earlier for the more rad aproach..i will elaborate if it works!

How do you mean, longer pulses?

And how have you measured (compared with a 2.0L) that you have longer pulses?

is this information you're keeping secret (no issue with that!) or willing to share?

My 2.0 clocked 587bhp, but if we ever get the 2.4 in the car (long and painful story of being let down), should I be looking at having a new manifold made before I bother getting the engine back in?

I've not read this thread word for word but am I right in think your running a 2.5" exhaust? Have you a picture of the manifold?

He is running a 3" exhaust and an external wastegate with separate exhaust

...seems you are in exactly the same position as me Rob.

Ignore the turbo, my engine spec is virtually identical, except for manifold.

Chatted to Barbz today about a lot of tweaks for my coop to come, suffice to say, the manifold can wait, although as the years roll, my engine needs a few tweaks to the CR & timing of the cams & a few other bits.

As I found out ages ago, the manifold is crucial, when I changed from a 0.64 turbine to a 0.86 housing, i gained almost 100hp, HOWEVER, even so, the engine is still struggling to breathe, so much so, I don't have a high rev limit ( for now ).

Fair play to the manifold supplier, however unless you start moving the turbo about, the larger use of primaries will be a monster for space...

Keep going, but to be honest a 2.0l will attain 500hp more easily than the 2.4 - 2.5 simply because of the extra volume being shifted.

Once the manifold is sorted, then you may attain JohnS figures.

good luck But don't expect overnight miracles, these aren't Jap engines

Sorry, but you are talking out of your bottom.

500 bhp will produce the same mass of exhaust, whether it is coming from a 2 litre engine or a 2.5 litre engine.

If you know different, please explain here....

ok, I guess I am

ever heard of compressible flow theory...

a 2.4 engine has a bigger volume ( positive displacement ), thus it shifts more gas, simple.

hence why a bigger engine can move a bigger turbo. Or am i missing something.

rated horsepower can be down to tons of variables... RPM, fuel, gearing, and of course cc.

A 2.0l will make the power easier as the stock manifold is better matched for the 2.0l block, whereas it's not for the 2.4l ( simply put, the flow is getting choked before even getting to the turbine ).

Or did you misunderstand my post ?

cheers

No, I understood your post. You seem not to have a grasp of the basics though.

500 bhp will produce about 50 lbs per minute of exhaust gas. A 2 litre engine will have to spin faster to produce 500 bhp than a 2.5 litre due to the fact it will make less torque, all other factors being equal, but the same mass of exhaust (and volume, if temperatures are the similar which they will be) will be produced for the same horsepower.

Think about it - if a turbo is rated at 500 bhp, will it make more power on a 2.5 litre than a 2 liter engine? No - because it is still only capable of flowing the same mass of air......

So, at 500 bhp, a manifold will be flowing the same amount of exhaust, whether fitted to a 2 litre or 2.5 litre engine.

And I would be pleased to be enlightened as to how gearing affects BHP - so please tell me.

I can assure you my grasp is good

So, each cylinder on my coop is say 20% bigger, compresses MORE air per stroke, burns MORE fuel per cycle, YET it goes down the same sized exhaust manifold ?

You will get higher gas velocity, but eventually it WILL choke, I've already found that out by changing turbine housings... ( wheel size the same ).

Don't confuse POWER with Torque, they are very different. My 2.4 makes less torque than the 2.0 on some others, as the head valve sizes are large, thus my gas velocites are different.

you also mix up the application of a turbo ( a centrifugal pump ) to an engine, a positive displacment.

The engine WILL choke if the outlet pipe is the same size & the cc has been increased.

Proof of the pudding anyway is that virtually most of the 2.4s don't make mega high figures, whereas the smaller cc 2.0 will make 500hp ( higher revs, higher boost ).

As I said, it's the manifold

A manifold has it's runner diameter decided by the valve size, nothing to do with the engine capacity. Whether the valve size suits the capacity is another matter again. A runner diameter wouldn't vary with target power changes but feasibly the length can be tailored to suit a power target.

If back pressure is a problem it's manifold or turbo (though the exhaust port can be left lacking too as target increases but I'll presume it's doing ok?) to blame but that's not to say a bigger exhaust wouldn't crutch the problem.

Yes. Because the 2.5 litre engine will be revving slower to make the same power as the 2.0 litre - funnily enough 20% lower rpm.....

Do you know what causes flow to choke in an exhaust manifold? 36mm id primaries will not choke the flow on a five cylinder, 2.5 litre engine producing 600 bhp.

The T3 sized inlet on the turbo will be having to flow the gasses from all five cylinders, and if it was circular it would only be 55.6mm ID, so the gas speed there is 209% of the gas speed in the manifold runners. If there was any choking going on, that is where it would be happening.

my engine will never get close to 600hp ( in fact the only one was JohnS ) with lots of extras...

partly due to the turbo needing to be a damn sight bigger & the manifold isn't up to it.

RE : my previous post on gearing, that is aimed at rated hp on a rr ( my fault ), however... the rest stands

If you know what chokes the flow ( other than the most obvious part, being the turbine wheel ), you'd make Barbz a happy man.

Anyway, you fail to recognize a 2.0 / 2.4 will all be revved to the same limits ( circa 7-7.5k ), hence the 2.4 literally chokes itself at the top end.

doubt it's the exhaust downstream, but more the critical part between the cyl head / turbo.

cheers.

I haven't seen any dyno figures of a 2.4/2.5 revving to 7.5K. If they do/can then at the same boost I would expect them to make 20% more BHP than a 2.0 litre. I don't know that the inlet and exhaust valves are up to flowing enough at those engine speeds though.

My take on things is,
2.0 flows x amount of gases,
then a 2.5 flows X amount of gasses times by 1.20 per bang.
therefore a turbo on a 2.0 might flow well up to 7k but on a 2.5 it will flow well only till 7k times by 0.8. Hence the bigger turbo is needed for 2.5. To match up well,
more volume or displacement ,

Therefore turbo on the 2.5 must flow x1.2 more than the 2.o turbo
And same goes for pipes,

Because we are talking about displacement here,


No point to prove here , just adding some input

Very good post - this is absolutley right!
It also is right, that the diameter of one exhaust tube depends on the valve size. Diameter should be at least as big as the effective valve size of both exhaust valves. To be smaller means a better torque in lower revs, but minor top end. To be bigger means lower torque in lower revs, but more top end.
Ciao
Juergen

Come on Barbz, settle this and explain...

I agree about the sizing of the primaries. However, once again if the exhaust valves and manifold on the 2 litre engine will flow XXX BHP then the same size valves and exhaust will flow the same amount of exhaust gas, and therefore the same BHP, on a 2.4 or 2.5 litre engine. The same amount of exhaust per second to be flowed will be at lower RPM on the larger engines than on the 2 litre engine.

IF it is intended that the larger capacity engines will produce maximum power at the same engine speed as the 2 litre engine, then in that case larger exhaust valves - and manifold primaries to match - will be required.

I am sure I mentioned my cyl head also has bigger inlet / exhaust valves ( I assume you knew that too ), thus the above is valid.

Not too sure what Stichl was agreeing to

That was my point. In fact it makes more power per rpm point ( up to a point as it still has the standard manifold, even though it has had the collector ported & the gaskets matched ). Not sure why you talked about 20% less rpm, I don't drive about at 20% less RPM

Full circle discussion ? Think so.

i can't argue technicalaties as i don't have the knowledge..all i know is put a 2871r on a 2l and you have full boost around 4k and it will rev out fine..put it on a 2.4 and full boost is 2800 rpm and it wont rev past 5500rpm as it chokes.thats fact..
another fact is we have tested and eliminated everything ..it is the manifold thats choking at just over 400bhp again thats a fact now..
whether its due to pulses,id or collector or amount of gasses it matters not it doesn't work so i have to find a solution
the 2.l has i think 28mm valves mine has 32.5 or 33.5 (will ask barbz as i cant remember) but with the seats done etc they will be a little better flowing anyway

the solution is what matters to me and though finding out why would help with that its likely to be more trial and error now i have more information..this is all helpfull whether it pins down the issue or not so please carry on with any suggestions you think may help with how to build the next one...as i mentioned i have an idea to try but if it does not work i will have tig art build to my spec so all help to this end is gratefully received

You previously posted: Proof of the pudding anyway is that virtually most of the 2.4s don't make mega high figures, whereas the smaller cc 2.0 will make 500hp ( higher revs, higher boost ).

If the larger capacity engines were able to flow 20% more air at the same RPM, then they would produce 20% more power. IF they did, they would need larger diameter exhaust manifolds. But you have said they don't, which is fair enough, but that also means you have to agree they don't need larger manifolds! What I am saying is that to produce the SAME power, the larger engines only have to flow the SAME amount of air - both on the inlet and exhaust sides. What I am further saying is, that because of the larger displacement, a 2.5 litre engine will flow the same volume of air as a 2 litre engine at 80% or the RPM. So we can agree on that too.

Following calculation:
36mm ID will give 1017mm^2 of area.
Your 28mm valves of your stilo head will give 923,6282402 [mm²] at 10,5 lift, with regard to your valve rod it will be ~800mm^2, only...
The 36mm ID are more than sufficient...
If you are going to install a bigger manifold than 36ID you will loose tons of torque, only...
Juergen

ok it has 28mm valves one side and 33.5 on the other

i only mentioned the 2871r above as an example of how differently the 2 engines act on the same turbo/manifold..all the calculations in the world can't alter the fact it doesn't work with the engine and turbo set up ..whether it should work or not doesn't really matter

also the engine revs happily to 7500 and on barbz the power is still climbing

does anyone have any suggestions as to what they think would be a good design?

any ideas on why it might not be working ?

Now you have confused me, because above you said "and it wont rev past 5500rpm as it chokes"

i think you may have misunderstood the post if you read it again you will see i said ..when you put a 2871r on a 2.4 that happens and it was not mine or barbz it was robs that ran a 2871 every time he changed his turbo to a bigger one he was able to rev it further untill now he has a 3076 .86 and can finally red line..

A pair of 28 mm dia exhaust valves does not warrant a runner with a 36 mm id, thats an area of 1018 mm2 which is not enough. It NEEDS to be 1 3/4" tube, NOT 1 1/2".

OK - so what size primaries does Rob have?

Also, what RPM is the "red line"?

Have you got any pictures of the manifold in question ? some of the inside of the collector and one of the whole outside would be helpfull in trying to diagnose the issue.

well it looks like i have jumped the gun a bit as have just had barbz on the phone wondering what i am up to and telling me not to worry i don't need to do this as he has already bought the bits and got a solution..apparently its not primary id or any of the things so far discussed though it is a manifold issue to do with collector and back pressure..he has explained whats happening in a way i understood but wouldn't care to try and repeat as i am likely to not do him justice..so it goes back to barbz monday..
on buying the manifold we knew there were 2.0l cars well over 500 with them and were assured they would be good for 600 though they did say they had not had them on a 2.5 so it was a bit of trial and error..
since the last dyno i have been speaking with the manifold makers who offered to make me one to any spec i want (and i return this one) hence me asking for ideas but barbz had, it transpires, been sorting it out anyway ..
knowing he had other work on for a few days i thought i would try and sort it out seems i don't need to
well thanks for the suggestions i would like to have seen where it got us but i will leave it to him as he wants to finnish it himself understandably, i don't suppose he needs my help

1nro i am interested to know what you think the id should be by your calculation

I' talked to Hartmut Lohman... (he was one of the engine builder of F1, when the cars had >1200HP turbo engines). It does not make ANY sense, to build manifolds with an area of much more than the "effective area" of the valves...
You will loose the velocity of your exhaust fumes, only which will result in a worse respone of the turbo because of lost kinitic energy.
Maximum acceptably is the area of the port at the end of the cylinder head, that’s about 10mm^2 of the Fiat Coupe...
Therefore 36mm ID is ok.
Juergen

A runner made from 1 3/4" tube will have an I/D of about 41 mm, this suits the dimensions of a correctly ported head (one with 28 mm dia exhaust valves) much better than 36 mm. It's not my calculation, it's common sense and a rule of thumb used the world over.

40mm ID are enough for 700HP cars with four cylinder...
I do not know your source, but it seems to be a good one :-)
Try it - you will see, what response you will gain...
Meanwhile almost all car producer tend to use the kinetic energy of
exhaust fumes by using extemely short tubes and divided / twin scroll technology.
This is most effective technology to get the energy of every single stroke of the engine...
But if you like to use the old technology of big / long tubes... it's your decision.
Juergen

Not sure why you'd call it old theory, if anything it's only in recent years that people have started using long runners. It's not a big pipe size, it's the right size. The dimensions of the port tell you to use this size, anything smaller is a restriction after the head and that's wrong. Pressure differential is what moves gases, to provide a runner that increases the pressure after the head is wrong, all day long :-)

I am glad that has been acknowledged.

just to qualify i don't know what the sizes will be and barbz as yet hasn't mentioned that... he has found another issue that is causing back pressure..whether he will want to do anything about the size of them or even use the manifold at all i don't yet know but i will post what happens and why .

Yes, it is right that a lot of people, especially in USA started to use long runners - but why...
They started to use very big turbochargers and did not find any place under the bonnet to install them – they had to use long runners to find a place to install the turbo- best example are Subarus etc - then some people might misunderstood this and thought, this would be newest technology…
I really don’t know the reason for very long runners.
A turbocharger needs one thing – kinetic energy coming from pressurized air. When do we get most of it – directly after the valves of the engine, if the exhaust fumes are REALLY HOT. Hot air has a very big volume -> this results in very big pressure (Otto cycle), which the turbocharger can use.
Examples: High power diesel engines like the new MT 892 HPD (tank diesel which does not need any emission control) use post-injection to get more exhaust temperature – this results into a better response of the turbocharger and more top end power (diesel engines have a exhaust temperature of about 800°C max…)
The same procedure does Anti Lag – extremely late injection of fuel, which exaggerated explodes within manifold and creates tons of heat…
Therefore the charger starts to spool in low engine revs…
But what do bad engine tuners… build 1m runners to lose more than 100°C within this long way towards the turbocharger…bad job.
What is the reason to use a certain length of the runners – a single runner (at turbocharged cars) should avoid interactions between the single cylinders.
Problem here: The cylinder being within power stroke should be unaffected by the other cylinders.
Because of valve overlap it can occur that certain cylinders cannot get rid of their own hot exhaust fumes because other cylinders (having been in power stroke one cycle before) try to compress their own exhaust fumes into the opening valve port of the actual working cylinder.
Best example is cylinder number 4 of of original Fiat Coupe 5cylinder turbo manifold. This primary simply is too short – therefore a melting of pistons normally starts here.
Therefore there has to be done a calculation – how long must be the primary to avoid this interaction – but not too long to avoid too much power loss because of lower exhaust temps etc.
Newer turbo engines go another way – they simply separate cylinders with different power strokes and use twin scroll turbos. No there is no interaction any more between different cylinders and now very short primaries can be used to get most of kinetic energy out of the exhaust…
Unfortunately a 5 cylinder cannot use this technology
Juergen

Hi Juergan,

The long runners used by some aren't just due to having no choice due to turbo size and location, there is real effort to harness the pulse energy that the engine produces and for this reason the longer pipes are needed. To use a short runner manifold makes the potential use of pulses impossible other than at very low rpm which really there is no point in. If anything there is a lot of negative work being done at higher (more useful for a powerful engine build) by the pulses when the manifold runner is very short, reversion is high and the pulses are pushing exhaust gases back into the cylinder even harder than they would be. A longer runner is far more able to resist cross contamination from adjacent runners and when the rpm is higher it is possible to assist the exhaust gases in their efforts to evacuate the cylinder. This higher rpm is where the ambitious engine lives and dies, every help it can get is good. The short runner just backs up and temps go through the roof and misery is close behind. A 1m runner is a bit over the top, about 2/3 of that length is relevant and isn't that long really. Too long for a standard position turbo as the runners end up in a right tangle but with a turbo thats positioned differently the runners are potentially able to be routed in a simple free flowing manner.

The point of highest kinetic energy is just underneath the valve seat (smallest cross section the exhaust gases will see), after the gases have been accelerated out of the cylinder the port expands towards the exit off the head, this is how exhaust ports are in all (for the sake of discussion) cylinder heads and this expansion is what assists in MASS flow. This is what the turbo cares about, MASS flow. Move more gas through a turbo and it will work harder. So having expanded the port towards the exit in a carefully ported cylinder head there is no sensible reasoning to then attatch a runner with a smaller inner diameter than the port exit. A 36 mm id runner has about 20% less area than the exit, this can only restrict mass flow when compared to a runner that is close to the size off the head. I've searched long and hard and no single person has managed to explain why a restriction to the gas flow is an advantage, maybe you can?

The exhaust gases are under pressure, even a very well built turbo engine will be lucky to get to a 1:1 ratio of intake pressure/exhaust pressure. This pressure is what keeps the gases moving through the turbo, all they are interested in is getting to atmo. To increase the exhuast pressure doesn't increase the mass flow, just the same as increased boost on the intake side doesn't increase mass flow. The gas momentum needs maintaining (the point under the valve seat gets everything moving plenty fast) rather than hindered.

Regards,

Nik

Jeurgen, I'm totaly with Nik and others on this whole ongoing primary dia topic.

Your considering heat as too big a factor, yes it helps to spool a turbo, but on it's own heat is useless. Pressure ratio is what drives the turbine, again - anti lag does not spool the turbo in low engine revs by the heat from an explosion in the runners, the pressure created by that explosion is what spins the turbo.

In fact imo loosing some heat in the exhaust gases is a good thing, a little less heat expected means you can run a bit leaner mixture this in turn produces more power, and improves BSFC.

Another point I'd like to make is when you talk about valve overlap and exhaust gas interference across cylinders, I don't think you fully understand the concept of interference and cylinder scavenging. This happens at the collector and is worked out not on the relativly slow moving gasess, but by sonic sound pulses which can CARRY gases with them to a degree. This is the fundamental reason for a designed length of runner, the length is calculated from the varieing sonic speed of these resonant pulses which reflect off a change of cross section, wheter that is seen in the collector it's self or in the pipes at a purposely designed stepped section. Another problem (and the point I want to make) is that with a small diameter pipe these sound waves are actually amplified in there intensity, and can be deadly to an engine if they are not 'timed' to coincide with vavle events by way of a certain length of travel ie; runner length. I don't see any reason why a 5 cylinder cannot use these pulses effectivly, but it would take some serious simulation.

Twin scroll uses this to good effect on OE setups because the cast, short runner manifold can be 'packaged' into a production engine bay, there is no other reason for using TS turbos other than that. We have the abillity to change our runner length and alter scavenging how we please.

On another note I don't understand the obsession with 'spool up' some people have, It's a turbo car at the end of the day if you want response build a naturly aspirated version. You can make more power at the other end of the scale anyway ie; far better to rev to the moon :-)

I understand the physics of a otto cycle fully, but it seems that you don't...
A turbocharger does not live from Mass flow, only - this is completely wrong! It needs a difference in pressure - means a difference in temperature.
If it is this way (living form mass flow only) - please install the turbocharger at the end of your exhaust. There you still will have the same mass flow like directly after the valves...
Only difference at this location is a loss of temperature!
Pressure and temperature is COMMON. You won't get pressure without temperature...
Please have a look to thermodynamics!
If you are right, then all OEM are idiots:
look here (has been one of the engines of the year)
http://www.bmwblog.com/2009/11/12/diet-turbos-how-low-lag-is-no-lag/
Information: BMW had very very big problems to get the turbos into this location - but they wanted to use all of the kinetic energy to get a good engine...
Thus for example they had to construct a special wire harness, which can do the heat, the ECUS got their own cooler etc. etc...
All modern engines have extremely short runners meanwhile. If you show me ONE modern engine, which has been engine of the year and which has long runners I will believe you :-)
Juergen

Well I'm afraid you contradict yourself because paragraph two of the link you just posted reads "There is tremendous energy in the flow of expelled exhaust gas leaving the engine.

This is where it's at, the turbine converts presure to velocity. end ov.

I can't help you Juergen, when you take your inspiration from OEM's and engine of the year awards. I take my inspiration from winning drag teams and real obsesive petrol head types. Watch this clip in full, proper tuning and performance in a car with 5 seats and petrol bought at the pump.

Look at the primary pipes, and notice how lairy the car is, not much "lag" as you call it to worry about there either. Come back and tell me those headers are too long or big in diameter.

http://www.youtube.com/watch?v=skly2gsdbyU

Coool - a "street car" which uses a anti lag system (listen to the engine sound) to get power in low revs...
I assume that this car will make peak power in 8000-9000s and before 5000rpm there will be absolutely no power without antilag (which will destroy the turbocharger definitely after some time)...
Do we talk about street cars or do we talk about 1/4 mile racers which won't survive one minute German Autobahn!
OK Tricky - I understand you
OEM's are idiots and ktm450exc want's to build a 9s Fiat Coupe.
Therefore I am now going to share your opinion:
Rob - your 36ID- manifold is not big enough to reach your 600+ HP.
My car, producing 565whp is not true, because my 34mm ID manifold cannot do this amount of flow...
No comments any more from my side to this topic.
Ps: I have edited my statement to mass flow and its physics behind it for you to understand!

Juergen

[quote=tricky]This is where it's at, the turbine converts presure to velocity. end ov.[quote]


Not sure you have that fundamental right. The turbine converts the kinetic energy in the exhaust into work done in rotating the compressor. The formula is: kinetic energy in the exhaust is equal to half the mass of the exhaust flow x the velocity of the exhaust flow squared, or Energy = 0.5 * m * v^2 - so you can deduce that gas speed is critically important.

For a given BHP, the mass of exhaust is fairly constant and accurately predictable within a few percentage points.

The speed of the exhaust flow depends on the volume of exhaust gas being flowed and the cross sectional area it is passing through – e.g. a valve seat area, a primary pipe or a collector/turbine entry.

The volume of the exhaust gas is dependant on the density of the exhaust gasses.

The density of the exhaust gasses is dependant on the temperature of the exhaust gasses.

A quick calculation shows that with a 2.5 litre engine producing 500BHP and a turbine entry temperature of 950C, about 73 HP of energy is contained in the exhaust gas at the entry to a T3 turbine housing. That falls to just 37 HP at 600C turbine inlet temperature – lower because inlet velocity will have fallen so much. In fact with only 37HP available, the turbo would not be able to flow enough air for the engine to produce 500BHP.

On the subject of choking, this only occurs as gas speeds reach Mach 1. The speed of sound is dependant on gas temperature, so in exhaust gasses with a mean temperature of, say, 850C the speed of sound is 690 metres per second. If the engine is operating with WOT, when the exhaust valve opens initially it will be operating in "choked flow" as the gas speed will be at Mach 1 at the valve seat.

At maximum flow, pressure in the manifold will be close or equal to the boost pressure the turbo is producing from the compressor side, despite the fact that 30%-40% of the exhaust gas is bypassing the turbine and exiting through the wastegate. This pressure is therefore substantially above the 1 of 2 psi extra any back pressure that smaller primaries might add to the system. As the pressure inside the cylinder will be far higher than the exhaust manifold pressure during the exhaust period, the differential in pressure across the exhaust valve will ensure the cylinder is emptied of all or most exhaust gasses.

Hi Juergen,

I've just had a read through some of the posts since this morning and to say there are opinions flying about is fair! I didn't say a turbo works on ONLY mass flow but rather it's this that it cares about. I'll have something to eat and try and write again afterwards in an effort to address some of the various opinions. I will say at this point though, we're discussing an engine that produces far more power for it's capacity than anything a mainstream manufacturer supplies to the public, the comparison is not relevant I'm afraid. I'll bet though that if you measured the manifolds off production cars you'd not find any that have a smaller cross sectional area than the port exit. Usually the problem is the exit is too big not too small. Show me a manifold that is a smaller size area than the exhaust port and I might start to sway a little :-) We'll not find a long runner manifold I'd agree but thats due to totally different design goals that they have (oe manufacturers) when compared with fella's that like to build high power cars such as we are talking about.

Regards

Nik

Very good explanation, Thank you very much.
Only additional comment from my site:
Chocking of exhaust flow starts at 0,6x Mach 1 (about 200m/s@~20°C) - this was the formula, I learned...
At higher temperatures Mach 1 speed is much higher, as you stated, it is not constant...


Ciao
Juergen

This is commonly quoted value and I am in no position to argue with it, though if you do some Internet research you will find others who are qualified and have argued against it extensively. It seems that the value "Mach 0.6" varies according to how the flow is affected by local turbulence - i.e. in a smooth straight pipe there is very little to cause turbulence, but splitting air over a wing section causes more flow separation at higher velocities and therefore more turbulence. What I will say though is that beginning to choke and actually choked are not the same thing; beginning to choke means that the rate of flow is not increasing in direct proportion to velocity, but flow rate will still increase with increased velocity up to the point of sonic flow (when it will remain constant) - it is just less efficient.

I have some "ball park" figures that I work with that illustrate the problem nicely. A well designed inlet valve and valve seat will flow efficiently up to Mach 0.333 but a well-designed inlet port will flow up to about Mach 0.533 before efficiency suffers. Neither of these situations can be compared to a constant diameter, smooth bore pipe, as both clearly require the air to make some radical direction changes around obstructions - the valve guide/stem, the SSR, the valve head and seat. The valve/seat combination is obviously more restrictive than the inlet port, but it is well known that a poppet valve has a discharge coefficient significantly less than 1.0.

Like it or not, flow in the exhaust will (at exhaust valve opening) be sonic - the pressure differential between the gasses in the cylinder and the pressure in the manifold of 6+ bar, and the must smaller effective area of the valve or exhaust port (whichever is the most restrictive) compared to cylinder area assures that - and there is nothing that can be done by the engine designer or us to avoid it.

However, going back to our 2.5 litre engine with 600BHP, 36mm primaries and EGT of 850C, the mean exhaust gas velocity in the primaries will be 283 metres per second, which at 850C is only Mach 0.41.

I agree with needing a pressure difference, why you'd increase the pressure in the manifold (where the gases are trying to get through) by using a runner thats smaller than the port I don't know. Thats just hindering ability to move from high pressure to low.
With regard to putting the turbo at the end of the exhaust we've been through this before Juergen and you didn't offer reasoning then either, please refer back to the post where I showed you a very fast vehicle that did have the turbo a long way from the engine, relevant pictures at the bottom of that page.
http://www.fiatcoupeclub.org/forum/ubbthreads.php?ubb=showflat&Main=90133&Number=1085252#Post1085252
I know about the temps involved with turbo charged cars, if you want to keep them sky high I can only wish you well. I consider the volume of exhaust as massive and easily capable of spooling turbos even when silly people put the turbo at the end of long runners.
The BMW link, I'm afraid I switch off when I read "During the ‘Exaust Phase’ of a four cycle engine, the exhaust valves open and the piston forces the combusted fuel/air mixture out of the cylinder with a plunging movement." It's an article written by someone who knows very little. It's hardly an engine to compare with what we are discussing though is it, whats it got, 50 bhp per cylinder? Thats not quite the same as 100 bhp per cylinder on your 5 cyl or 150 bhp on a real engine like a 16v 4 cyl is it
Instead of refering to production engines I'd advise seeing what people do with performance engines that break the rules you are living by. An example a friend of mine helped design and build is worth quoting you, this breaks the rules you say are impossible but it's very true and not rare, there plenty like it around this worls.
"One example is a 1.9-liter inline 4, max revs 8200 rpm, 25 psi boost max, reaches this at 3870 rpm in 3rd gear as per the log the customer showed me.. That little thing makes 5 psi at 1700 rpm - and, already by then it pulls well and I would not call that an "useless power range" - and close to 420 whp (actually hub hp). At 25 psi boost and 7700 rpm the EB was 22 psi."
That's using a GT35 based turbo, completly true and more than possible.

Regards,

Nik

Nik

I completely agree that it would be wrong to have primaries with a CSA less than the exhaust port exit at the head - no argument there at all. However, the debate was about whether 36mm primaries would choke the engine, which they won't. The port area was not mentioned, although the valve size was later in this thread. I would argue that the effective valve area is in fact the area at the diameter of the inner valve seat less the area of the valve stem. In that case two 38mm valves with 7mm stems have a flow area of about 900mm^2, which is equivalent to a pipe of about 34mm ID.

However, I agree as a rule of thumb with using valve curtain area as the basis for calculating primary area - but I would use it to say that there is no point in going to primaries larger than that area. In a N/A engine, without the massive back pressures which a turbine in the exhaust flow causes, I would also be looking to minimise back pressure, but in an extractor manifold that is usually achieved by ensuring a high velocity to cause low pressure in the collector/s to provide 'suction' at the collector end of the primaries.

The debate about long and short exhaust manifolds on turbo engines is an interesting one. Subaru, and of course Porsche before them with their single turbo engines, had no choice but to use long runners on their boxer engines – and they can obviously work very well. Short runner manifolds are able to utilise the pulse energy in the exhaust – perhaps better than long runners - but there is no opportunity for wave tuning. Pulse energy gives greatest benefit in spooling up the turbo when the mass flow is low. However, at higher rates of mass flow the pulse energy becomes less and less significant to the performance of the turbo. What does that mean in real life? Well, the way I see it is that an engine that is often used to accelerate from low through medium to high speed will make better use of pulse energy than an engine that is always operated at higher engine speeds – so a road or rally car would do better with a short manifold and a race engine would do better with a long manifold.

The other thing about pulses is that they get reflected back down the manifold and this can be detrimental to performance. In a four-cylinder engine there is always one cylinder on its induction stroke while another is on its exhaust stroke. Should a positive pressure pulse from the cylinder on it’s exhaust stroke be reflected back and arrive at the wrong time it will add to pumping losses on the cylinder on it’s exhaust stroke, but worse still impair the cylinder filling in the cylinder on it’s induction stroke. Very short runners should ensure that the positive pulse reaches the exhaust cylinder before it reaches BDC where it will have the least impact on pumping losses, but at this time the cylinder about to start its induction stroke will have both the exhaust and inlet valve open, so the positive pressure pulse may cause reversion and push some of the incoming charge back out of the cylinder.

The conventional way of dealing with this problem in a 4-1 manifold is to have runners long enough to delay the pulse, such that on its arrival back at the exhaust port on both cylinders the exhaust valves are closed and the pulse will cause no harm. In a 4-2-1 manifold, cylinders which can’t interfere with each other are paired – in most cases this is 1&4 and 2&3. Because these pairs don’t interfere with each other the pipes connecting them – i.e. the 4 into 2 part - can be much shorter (though the total length to the final collector of the 4-2-1 manifold will be much the same as a 4-1 manifold). The shorter manifold benefit of connecting non-interfering cylinders together in this way can be enjoyed on a turbo engine if a divided inlet turbine is used; pulses reflected off the turbine wheel can only go back to the two cylinders that are connected to the same inlet.

Looking at the BMW article mentioned above there is a picture of the F1 Brabham powered by the four cylinder BMW turbo engine. You will notice that the primaries are quite long – certainly much longer than on the V6 turbo cars of the same era. This is because the three cylinders connected to their own turbo on either side of the V do not interfere with each other, as their firing cycles are separated by 240 crank degrees rather than 180 crank degrees on an IL4. The Hart 4 cylinder turbo of the same era also ran long primaries. An educated guess is that the reason for this is to reduce the power losses that would come from reflected pulses interfering with induction, adding to pumping losses or both.

So on an engine that has interfering cylinders connected to the same, single entry turbo, longer runners would probably give more top end power. Designing one to do the job is a complicated business though. The maths is quite straight forward, but defining the task is not so easy.

The first complication is deciding at what engine speed you want it to ‘work best’ – because what will work at high RPM won’t work at low RPM when the time between valve events is longer. The second complication is at what exhaust temperature you want it to ‘work best’. This is because the speed of the pulses is sonic, and the speed of sound varies with temperature. So, higher revs = shorter runners, higher temperature = longer runners. As most petrol engines will have a fairly wide rev range, and due to varying loads widely ranging exhaust temperatures. You will also need to know exactly when the exhaust valve opens and closes. Deciding these parameters and ensuring the engine operates within them is key to designing a long runner system. A long manifold is, in my opinion, much harder to get ‘right’ and easy to get ‘wrong’.

I think this is the main reason, apart from packaging and perhaps better spool up, that short turbo manifolds are most commonly offered in the ‘aftermarket’ and that longer manifolds are really best suited to specialist applications like circuit racing, or forced on the aftermarket because of packaging in the case of Subaru!

I was tempted to quote again but thought better of it, it's a huge page now!

I'm sick of picking posts apart so will resist now, we could go on and on without end.

Just for interests sake though I've just been measuring a 20vt head and it's exhaust ports. I'll admit to not being 100% accurate as I didn't pour a port mold to measure but measuring carefully with some tools I have and crunching some sums I see how the unported head has an exit out of the exhaust port of just less than 1300m2, not the big gapping exit but the expanding section as it moves away from the seat. There is no doubt in my mind that a 36 ID runner does nothing other than restrict the very thing we'd like to be free flowing. Cross sectional area is where it's at, carries right through an engine. This was the discussions point wasn't it.

group5lancia, not critisim I enjoy your posts but just a few comments on what you have written.

36mm primarys won't choke the flow, but they will still form a convergeance when ideally we want a divergance or 'megaphone' effect to help with the PD. Valves flow very diferently remember depending on which direction flow is oriantated, an exhaust valves head doesn't pose a restriction like an inlet due to it's opposite flow direction in the same way gas is almost insensitive to exahust valve seat angles as opposed to inlet ones. Therefore the smallest controlling section is always the throat and never the curtain area, down the port then widens out to the gasket face as this trend needs to continue into the runner and therefore decide it's ID.
Thats my take on what the gases actually 'see'

Runner length is based on the needed powerband, max rpm and is largely related to cam timing as you have said. Just to throw a spanner in the works :-) I have had my own exhaust manifold designed by simulation recently by a specialist exhaust company using all the parameters from the engine (16v) with a powerband of 3000-8000 rpm and for my fairly modest cams a runner of 22" total was predicted, this is on a road car just for your interest.

I have my suspision what ID of tube you personaly would pick for lets say a nice 16v engine, but what size do you calculate is best ?

Just some other thoughts on 'lag' or 'spool up' people too often confuse this with boost threshold, ie' "My GT 35 is really laggy", no it's just a turbo that technicly is far to big for the kind of exhaust volumes your engine is capable of ever flowing.

The trouble with it all is that it's such a re occuring problem because the inlet side needs the mass flow to produce the cylinder pressure to produce exhaust volume to power the turbine wheel to turn the compressor to create mass flow, so we're back to square 1 again. It's a chicken and the egg problem, Mass flow from the compressor is where it starts NOT in the exhaust side imo altough saying that if you fiddle the exhaust cam timing a few degrees you can make better use of the cylinder pressure by way of early EVO which will pulse the turbine a little more at the expense of usefull work from the expanding gasses to drive the piston again another chicken and egg situation !

Lag is a transiant, if your charge air is'nt hanging around in the intercooler, there's not much else that can be done IMO. People seem to go to all kinds of strange lengths to irradicate it, like small primary tubes ! or ITB's or 2" pipework because it takes less time to fill ! But at the end of the day, just pick a turbo that matches your rev range and just wait for it !

Agreed about the better flow coefficient of an exhaust valve compared to an inlet valve. What I have hi-lighted in your post is what I was saying above about the 28mm valves - if you calculate from the curtain area you would end up with primaries which are larger than necessary.

Curtain area doesn't feature in the sum to decide the ports throat, it's the valve diameter that determines sizes throughout the port which in turn carries through into manifolding.

OK, but I believe calculating the primary diameter from the valve area based on the overall valve head diameter is wrong, because the flow at the valve is not determined by the size of the valve head, but the size of the hole the exhaust must pass through! i.e. the valve throat area minus the valve stem area. Anyway, it works for me!

Oh yes, I think we all sing from the same song sheet in this area then.

How do you calculate valve curtain area group5lancia? or do you have a simulation program that does it for you?

If you calculate it physically how do you cater for cam lobe profile varience? also, what circumference do you decide on as being the curtain area?

I calculate peak and mean - both from published cam duration and clearance info - or if I have mapped a cam, directly from the profile.

However, in my last post I was agreeing with you that the curtain area is the wrong thing to use when calculating primary area/diameter - it was a slip on my part. But I don't agree with using valve head diameter/area either as it doesn't represent the flow area - I gave my reasons above.

Now this is getting even more interesting, could you potentially use a combination of valve throat, even say minus the stem dia and the max valve lift to calculate curtain ? And is it of any use to us anyway ?

- Not moving over to the dark side are you Nik ;-)

not being funny guys but this is clogging up a post if you want to talk flow and valve design etc etc then start a thread about it.

I be following it anyway i just think it is unfair on ktm's thread

Can Rob not chase us if it bothers him or are you his keeper? It's a bit late to tidy it all up.

@ group5lancia
"i.e. the valve throat area minus the valve stem area. Anyway, it works for me!"

I've read it more clearly now, just looking at a phone before. The reason I refer to valve diameter is that it is part of what determines the throat size and inturn the runner size as you said.

@tricky
"Not moving over to the dark side are you Nik ;-)"

Not really but the 20vt is a great engine, I look through the classified section often enough and would buy another as I miss the one I had a few years ago.

You should come over to evocorner, you could spend a year trying to orginise the 500,000 long threads and not touch the sides

Ye, I suppose it's alright in it's own right. I would'nt throw money at it though.

Nobody is his keeper, but you are filling up pages with unrelated waffle.

We're interested to see how Rob's car progresses, not how much you can write about something that interests only you and a couple of other people.

I think you might find Rob himself is interested in what has been discussed. I'll not bother maybe?!?

ok guys don't start reaching for the hand bags yet

firstly i'd like to thank the guys involved for the information and time they put in

my fault for any issues as i was happy to let this run for the mine of information it unearthed which i should have realised was of no interest to anyone but me and the guys debating

knight thanks for the thought but as i say i allowed it to run i'll explain why in a minute
biggenz my apologies to you and anyone else thats been reading just to generally keep up with how it's going..i am still getting regular texts asking whats happening from all over!

the reason i was happy for it to go this way (though i now realise i should have opened a different thread) is barbz has built me such a sweet motor that to stall at the manifold and not be able to go any further yet is so bloody frustrating especially after buying the best on the market in terms of quality

i am desperately trying to take in as much as possible about manifold performance and design and there is so much information that comes from the main players in this that to me it's all i could wish for..if the solution we try next doesn't take us far enough i will have to have tig art make me a new manifold which they are happy to do free of charge but i have to design it! daunting for someone as clueless about manifolds as i am..ok i have barbz who although brilliant is not a manifold designer so i didn't think any thing but good could come of this thread and the way it's gone.. from my point of view that is

i will try and keep it to it's original subject matter from this point

i personally think the WAFFLE Is very interesting and educational! Obviously the 'knight&biggenz' tag team don't....

nick

It was all reletive to the issuse, I followed the whole thread from the begining. I suspected the collector might be at fault at the point when I said "can we see some pictures of the inside of the collector".

Forget Tig art, if this build is as serious as you make out you will want better than that.

Okay, so Tig Art are the company that made the manifold? And if you are saying 36mm ID, then that says to me it's this manifold, whereas, if you look at the 16v manifolds they do, the 'race' spec has 40mm ID and the normal one is 36mm.

right for a start i am enjoying the knowledge and info brought to the thread but what i was saying is it would of been better in its own thread and not in this one.

begbie that is interesting you should point that out as i had no idea they did 2 manifold sizes for the 16vt if i had spotted that from the start i wouldn't be in this situation as i would have queeried from that point..
it seems they only do the one for the 20vt and thats why i ended up with 36mm.. if i had had an option it would have been 40 straight away ..
they did believe the 5cyl 36mm would do the 600 though and have 2l's at over 500..though they had never run one on a 2.5..
for now that is all i can say
guy (the owner i think) seems a genuinely descent individual and is going to do all he can to make a manifold to do what we require so watch this space for results..the biggest issue with that is i am having to state what we require hence me encouraging and appreciating this technical last section to the thread

Well now you know it needs to be 40mm ID , what about the other variables - (not in order of importance, as there all important factors)

1> Material choice,
2> Collector merge angle,
3> Collector outlet size,
4> Runner length,
5> Bend center line radius,
6> Expansion allowance.

The ID is just one small part of the bigger picture, I haven't put equall length because that pretty much goes without saying.

I can help you a little with 3 or 4 of those on the list but, surely Tig art should know ???? I guess what I'm saying is if they don't and are asking you to design it, somethings not ringing true prehaps.

also

Manifold headflange that's not causing trouble
Exit angle off the head for the runners
Symmetry of the runners when compared to each other
Symmetry of the exit off the head
Symmetry of the approach to the collector
One of the hardest things, no cheated joins. It's so easy to settle for not 100% perfect join but there's a lot lost if your not that fussy. Unless you make your own though you'd never know if it was truely as good as it can be.
The order the runners are arranged around the collector.

The list goes on and on.......

Again an nice surpise to read all of this. If i only had some 20v flanges i would love to struggle a bit .

If you would make your own, you will never be happy 100%.

And in my case not even 50 maybe :0.

You all do know that you made it impossible to have an decent manifold for him now. The money,design,fabrication etc etc will cost him a fortune. If you have time enough then i might be easier to get it a bit right.

Only 50% happy, that's a bit harsh on yourself. I agree though to be fully happy is probably impossible but I'd say I'm 95% happy with mine.

Not even touched on welding tech yet ! - i'm starting to put myself off now, better shutup

Thank goodness, that the Integrale is a 4 cylinder and no 10 cylinder engine...
With your mathematics you then would adopt the same diameter for the tubes as well?!
5x36mm tubes do minimum the same flow as 4x40mm tubes...
An example
http://www.youtube.com/watch?v=nG9gXerj8v4&feature=mfu_in_order&list=UL
This Integrale belongs to Markus, he has a manifold with 38OD - outer diameter!!!, uuuups...

Juergen

Not that impressive the graph, a big power number at 5000 rpm then nohing but weak revs all the way to 7500, I wonder what could be causing it ????????????????

Very first comment posted on you tube,


" great car!

if you can find a way to just keep the boost on higher rpms..that would awesome!

i think you can reach almost 600hp and a better sprint of course.

that's too bad the torque falls down that much at 5500rpm...isn't it? "


Again I rest my case.

Hahaha...
Yeah - now I understand you... it's the manifold, which restrict's the performance of his car...
Maybe that Markus will get more power out of his small Garrett GT30 unit with a 40mm ID... :-)
This is the best Integrale with Tuev in Germany. And I bet, there will be probably no Inte's in UK with such a performance and TUV for legal daily driving.
Ps: Markus wanted a street car with boost in low revs, no 1/4mile racer, as you prefer...

Felix Pailer, the best hill climber in Austria, has a 40mm OD- manifold with twinscroll technology for his Integrale... he drives a GT3582R with 1,06AR and about 650HP
But I think, in your opinion this manifold is too weak as well... he could gain 700HP with a 41mm ID for sure :-)
http://www.youtube.com/watch?v=jzOMhjmzxUw&feature=related

Juergen

not wanting to give the wrong impression i will clarify the tig art situation..having only mentioined they wanted me to spec it may have given off a vibe of not quite knowing what they are about... but what they wanted me to do was give them the id i wanted,and to specify as much as i thought would make it good..i think they thought i knew a little more than i do!..so length of runners,where i want the turbo,how i want the collector etc but i have spoken to them this morning and they are happy to do whatever we want from refund to design a new one.. for me to me specify everything or any stage in between..he has offered to design one which he thinks will work better with longer straighter runners as the one we got was the superstock designed for stock 2l with maybe bigger turbo etc whereas we have quite a different set up which they have never tested or even seen before...i do need to know enough to make sure it looks likely to work before it's made and i give the go ahead but i feel confident this will come to a good conclusion after speaking with them again this morning...anyone want to stick thier neck out and saywhat they think would be the way to go?

I'd take the manifold and turbo off the car and create as much space as possible and then offer up just the turbo in the space you have until you are happy it's in a position that best suits exhaust route and easy routing for the runners (not forgetting the oil drain needs though that can be got round even if mounted very low). Make a bracket to hold the turbo where you want it, do a good job of this as it'll likely be permanant. Then make a simple jig that can be sent to tigart, doesn't need to be anything fancy just something that will survive shipping. If your struggling with the jig send me a mail and I'll do you some pics and explanation.

Do you really have enough information about the engine to be able to explain the shape of the torque curve is purely down to the primary pipe diameter? I really don't think so.

Three things I would note: 1) The engine is producing 576PS from 4 cylinders, therefore a five cylinder engine would be able to produce 720PS with 5 primaries of the same diameter without a problem. 2) a GT30 is pretty much maxed out in terms of flow at 576PS - it is rated at around 53lbs/min I believe - so I would think the turbo is a limiting factor in this case. 3) I know I am repeating myself here, but 576PS at 7000 RPM would produce the same mass of exhaust gas per second as 576PS at 5682 RPM does and so would place exactly the same demand on the manifold primaries, so an engine set up with lower boost, but producing the same power from the same mass flow at higher revs would have the same exhaust requirements.

Question: If you join 5 primaries of 41mm ID - total area 6600 mm^2 approximately, into a collector, by your estimation/calculation what area would the exit from the collector need to be to avoid choking?

You are right I dont have enough information to say the primary D is at fault, but what I will say is that we are still discussing small displacement engines, OK and a 2.5l but not 3l - 6.6 litre range. So which ever way you look at it they still need to rev to make power and a small cc engine that can't breeth at high(er) RPM is a pointless excersise.

Watch this space

ah now heres something i have neglected to mention we are not making the power we expected to make anywhere..at 1 bar we are well down on a standard manifold and gt30 set up and we are only mapped to 6k as we had reached the 407 threshold but still hadn't gone further than 6k ..(just thought i would add that little snippet).. but whatever the boost we couldn't make more..i was going to set the limiter to 7600 or 7700 depending really on what was happening

i am however on full boost by 3200 revs which i like

The same car with 525lb/ft of torque and 568BHP @ 5682 RPM will achieve the same top speed but out-accelerate the car that fitted with an engine producing 397lb/ft and 568BHP at 7500 RPM, so I don't understand the need for higher engine revs than are necessary to deliver the target. In this case I'd say the target has been pretty much achieved as the result is more or less all that the turbo will support.

That would suggest to me that the problem is probably somewhere else in the setup. Not being funny, but have you double-checked the cam timing?

why am I answering questions in the style of straight and when I ask all I seem to see is either no answer or something that skirts round the edge?

The collector exit is sized to complement the entry into the turbine scroll, not the same size as it and in honesty I'm not saying which way of that size but something close to it. Common sense will tell you the approximate size :-)

I just thought you would know the answer - that's why I asked you. You made a statement about primary size based on valve size, so I'd like to understand the whole picture by knowing the proper sizing for the collector related either to valve size, or primary size - if there is such a thing. The answer you have given doesn't really deal with the choking issue; what will cause the choking to be in the collector rather than in the primaries? (which I imagine could happen if the collector was too small).

Certainly for a normally aspirated engine, there is a relationship between the area of the primaries (whether that be two, three, four or more) and the collector area. I would expect that to be true of a turbo collector too, but I guess from your answer it's not critical. In the case of a T3 the exit area would be about 2426mm^2 and in the case of a T4 about 3810mm^2, so the velocity in the T3 entry would be 1.57 times that of the velocity in the T4 housing, all other things being equal - does that not matter? Wouldn't there be a big difference in back pressure?

There isn't a definative answer for much in an engine, more usually a ball park area and scope to shape but certainly I'd see the collectors smallest point being in the 2426 mm2 region. I think as long as it's close the biggest gains are in the radius either side of it. I'm not sure I know much about creating a choke on the exhaust side, I'll leave that for the turbo to decide.
A turbo engine deserves as much effort as a NA, built to be a good one of them but boosted (obviously not massive Cr and there are other differences I know) is the way forward in my mind. Critical is my middle name even more so to myself.

A 10 cyl integrale! that'd be amazing

If we can hatch a plot to build it Juergen and we can fit a pair of 28mm exhaust valves in each cylinder I'll be fighting the corner for a runner made from 1 3/4" tube.

I don't know him but without doubt Markus has a fine looking integrale. Trouble is he's not proud enough, very little moving footage even after watching all the videos (accelerating away like he was is like integrale do) and absolutly no engine bay pictures. Where else can I learn a bit more about Markus and his car? I'd like to see the dyno as it ran live and look at the jewel that must be under that bonnet

weak ? what graph are you talking about ???

that car peaks quite early but still holds 550hp and way over 500nm up to 7500rpm.

and look at the other videos and the speedo. that car is rapid !

like group5lancia already said we unfortunately don´t know nothing about the engine specs or especially the boost curve of this car. so none of us can really explain the shape of the curves....


macki

Having spoken to him a couple of years ago when I had my engine / manifold failure, he was running a slightly different manifold (scara) than I was, running a GT30 and a 38mm ext. wastegate with a lot of boost, approx 2 bar IIRC, but alas, I don't have the email from him anymore

Ok maybe a bit more then, but really not much more to be honest.

Everytime when i finish something, i see what i should have done different. Easy when things are done, but pff, hard when you are working on it, and it has to be finished within an certain period. (always to late .

Time and patience are vital if you ask me.

Tried to cut some corners with software, but when i went to hec ( holland engineering consultants ) i got some serious doubts about the parameters that were put into the programm, so much for timesaving sadly enough.

Btw. was there not an very very nice evo with about 570 bhp, running with 38mm od on pistonheads if i remember correctly?


You are finished with your mani project then, if you are already 95% happy with it?

Time and patience I have and so true, absolutely vital.

No, it's not finished but it's only a little bit of welding needed and that'll be fine, the guy doing it won't mess it up.

Weak, was an unfair use of the word. I've known about that car for some time and like it very much (like all delta's) and in truth hope my own car makes those kind of figures, my point in response to juergen was about the breathing efficiancy of an engine, wether it be the exhaust or inlet side or the camshafts abillity to control pressures accross the cylinder.

Unless you have an insanly large hotside, choking will always occur behind the turbine wheel at higher revs and dependant on the boost level needed (exhaust mass) a properley sized wastegate should not choke at these higher points. I would expect the outlet from the collector to easily cope with the full situation.

Thanks - good answer. So, if the turbo inlet of CSA 2426mm^2 will not choke the mass flow from five cylinders, surely any primary with a CSA 1/5th of that area or larger wouldn't choke the flow from one cylinder either? Or am I missing something?

Your missing what gases would prefer whilst maintaining enough velocity

Obviously! - can you tell me then?

Instead of winding yourself up trying to fight some corner your wanting to camp in I think you should read what I've written, the answer to your last question is in there.

I just want some numbers so I can get a handle on it. At the moment it doesn't make sense to me - but I hope it will do after you or Tricky explain. So, if you could be a little less cryptic I would appreciate it!

p.s. to be clear, I have no corner to fight!

What number would you like?

Well, the ones that I can use to calculate the area relationships between valve/primaries and primaries/collector. The first part you have covered i.e. valve/primaries - so just the second part I guess.

Let the collector MCSA be determined by the turbine housing entry, you are about right with the area as I said.

So, are you saying, there is no science behind it - it is just whatever it is?

There is an exact science to collector outlet D in a N/A engine, I don't know it off the top of my head but I will look it up later on. On a turbo unit, from what I can gather the dimension is'nt as critical as the former.

Flow not being at choking point does not nesacerilly mean no restriction either. You can still have sub-optimal flow and not be at choke.

Thanks Tricky. But what would indicate a sub-optimal design. Is there some critical gas speed to look for in the primaries and/or the collector maybe? And, if you have selected your primaries based on valve size, if you then switch to a T4 turbine housing (which has a larger inlet area than a T3) should the primary size be re-considered? Or, if the primaries are the correct size, does it not matter what happens at the collector?

What do you mean by science? a sum? No equation for that I've ever seen but likely someone could work the numbers into somehow matching various turbo flanges but it'd be a mind flexer. When push comes to shove it has to suit the turbo so within those constraints maybe you mean subtle sculpted radius and the science involved in that? At fabrication stage the detail is at the mercy of the craftsman (or is he a tradesman who couldn't be called that), has he any gray matter applied to his job or is it a repetitive skill? Maybe he takes a lot of time on a never noticed detail or maybe he wondered what it was that he was making that day or hell, he might of been up all night reading something related. Science I suppose is in every detail if you let it.

If it's a definative answer you crave you'd wait a long time, nothing ever could be to my mind as no two builds are the same even by the same person. To be in the ball park area is possible and in this case plenty enough, after that the devil is in the detail. Only after multiple manifolds with extensive testing could it be dialed in closer to optimum. Maybe you can amaze us all with a modular manifold that can be chopped and changed to the best results, on that application.

Hopefully your going to side swipe us all with a fantastic sum

Sub-optimal is the skinny runner theory, think of the engine as N/A - gas needs to expand it's way out of the cylinder. The turbo does it's own job of speeding it back up again, no need to do it right after the port.
I don't think there is a critical gas speed to look for in the tubes but maybe in the collector yes, which is what a proper merge collector is partly about.

I don't think the pri. size need be reconsidered for a turbo swap, but going from say a gt3071 with a .63 AoverR to a 3582 or a big T4 says a lot about how your use of the car has changed and prehaps a different runner length might be more suitable and indeed the outlet area at the housing could need to change too, possibly meaning a new collector if there is a big area increase.

Highly unlikely, I'm afraid. Everything I had thought I understood to be true about turbo exhaust manifold design criteria has been totally debunked by you and Tricky, so I can offer nothing constructive.

That is exactly the case. Doing a straight swap of the existing turbo and manifold (design parameters, not the physical manifold of course) onto a 16V 2.1 litre engine from a 2.0 litre 8 valve engine will give too much torque (for the drivetrain) at 4000 RPM but run out of flow before 7000 RPM with the better breathing engine, never mind supporting the 8000+ RPM target. The T4 I have would seem to match the torque and power objectives and eliminate boost creep problems, so I have to amend the design to that. Lengths I am not worried about, as I have confidence based on previous efforts that I can get that right - pulse tuning is no different between NA and turbo engines except for the effect of higher EGTs.

Are you bound by regs, why are you using a T4 ?

'cos I have one! - And it matches the flow I need.

Thats fair enough, but I would have thought a more up to date unit would be top choice ?

I can't stretch to a ceramic BB unit... there is a recession going on you know...

I hadn't noticed one ! Save up, theres tons of choice on tubbys these days and the eficianys are sooooooo much better than the old skool. Even the smallest frame billet gt30 can flow enough for nearly 600 hp at lower boost and around 6-8% less heat input .

What I have is more of a T4 plus - it's a bit special... It has current design "aero efficient" turbine and compressor wheels. The cost of ceramic BBs and non-plastic cages is the big problem... If you can find me one for less that a grand I'd like to know where...

I know what your saying, I just spent twice that on the same item, not cheap with all the extras.

Just spend the money with Burns and get a double slip, they'll get one of the craftsmen to do all you could wish for in a collector. I'd run the turbo and see how it behaves, sounds capable of the target power without being pushed too hard so unlikely to disappoint and hold the blame on it's own.

Of course they are expert craftsmen and could make a very pretty one - but I can't tell them what I wish as I can't define a specification at the moment.

I guess I will have to find some expertise somewhere, or do some reverse engineering.

That's the beauty of Burns, they'll take all of that under their wing and provide you with what you need rather than what you tell them. It is expensive I know but well worth it on a number of points.

They don't sell collectors 'online' as everyone is different.

Fill this out and send it.

Please have a look to the new Borgwarner EFR turbos...
These are the first units since a long time capable to outperform the Garrett units...
Please have a look here:
http://www.full-race.com/articles/borgwarner-efr-turbos.html
The new Garrett GTX units like my new GTX3582R are great and have more maximum flow /power than the older GT-units at the same response, but they still suffer from old stuff on the hot side...
Means, design of their turbine wheels has been unchanged since launch of the GT units…
Really bad is the quality of the turbine housings… Meanwhile I rework every housing regarding clearances from turbine to housing…
Thus I found a housing, which had a clearance of >>1mm from turbine to housing because of cast tolerances. Therefore I had to cut back the housing.
If I would have the choice to test a new unit, I would try the EFR8374 single scroll (with my 5 cylinders), with a 4-cylinder I would test the twin-scroll housing, which promises significant more response…
Unfortunantely a 5-cylinder engine is no adequate unit for a dual scroll turbo.
Juergen

The EFR stuff sounds very good, I'd also like to try one out some time. I agree on the garrett castings, not the best but at least you can upgrade to stainless.

stichl the 7670 any ideas on the type of power a 2.4 would get with the internal gated .83 housing? i am tempted

I agree Borg Warner seem to have made a serious attempt to produce a range of turbos that are designed from the beginning for petrol rather than diesel engine requirements and at the same time a serious challenge to Garrett. They are very expensive though it seems. The other thing that concerns me about them is the compressor maps. The compressors are very efficient but seem to be designed to be used at very high boost as they come into their own at pressure ratios of 3:1 and up. The .83 A/R 7670 or 179351 is a 600BHP turbo, but at 2 bar boost looks to only flow about 550BHP for example.

wish i could read a map! but thats a lot of boost is the 8374 the same?

I haven't looked at that turbo so closely. For my application it will be a bit too slow in getting going.

On a 2.5 litre it would look something like this at 1.6 bar:

http://www.turbodriven.com/performancetu...rsin=92044&

which turbo is that? the 8374? and it would be roughly making those figures at 1.6 bar?..is that the internal gated one?

It's an 8374 with the 0.83 A/R internally wastegated turbine housing. The actual power it will make will depend largely on the volumetric efficiency of your engine and the intercooler efficiency, but the turbo seems a good match for a 2.5 litre engine (too big in my opinion for my 2 litre though).

i would really like to know what mine should be doing

I can't find a compressor map for your turbo - maybe you could contact the manufacturers or suppliers for one, but I have read that the manufacturers don't publish their compressor maps for some reason. Without a compressor map it is pretty hard to tell what the turbo might be capable of - you just have to trust what the manufacturer tells you.

I think it might be based on the T04E 60 trim wheel though. Maps for that are available.

I havent studied them at any length, but I have heard that said about them a number of times on the web.

Have you played with the matchbot yet ?? It's excellent but obviously isnt loaded with garrett maps I wish they would do something similar for the GT range.

Oh yeah, you might find this interesting.

White paper

If you follow the link I posted a couple back, it is to the Matchbot for 2.5 engine - don't know the correct VE or intercooler details for this engine, so the Matchbot gives only a guide - possibly too optimistic for peak power.

Apparently, if your can program in Java, you can adapt Matchbot to do Garrett maps too!

Interesting threads for you regarding this topic:

New EFR7670:
http://forums.nasioc.com/forums/showthread.php?t=2135597

New Garrett GTX turbos:
http://forums.nasioc.com/forums/showthread.php?t=2110277

New GTX3582R:
http://forums.evolutionm.net/evo-dyno-tuning-results/447351-highest-hp-4g63-engine-2007-a-34.html

In my opinion best match for 2,4l are:
GTX3582r or EFR 8374

Best match for 2l engine:
efr 7670 or new GTX3076r

If 560HP are enough, best new match is GTX3071R...

There is a hype meanwhile in US regarding EFR turbos...
but the evidence, that they really are better than new GTX turbos, still is been missing...

But if seems that all other turbo manufacturers cannot compete against these two brandnew turbos any more...

Juergen

Oh you have found it !

The likes of FP and precision turbos have been producing thier own billet "HTA" wheels for years, it is Garrett that needed to keep up !

Yes, it's a good read. I use the "energy conservation" method myself to estimate back pressure. Inputs are boost pressure (Pim), air charge temperature (T1), cylinder size, VE (nvol) and A/F ratio to give mass of air and fuel in cylinder (maf). EGT is from logged data and Tr from published data. Compression ratio, along with engine size, to give Vd & Vc and engine speed (N). Wastegate flow comes from logged wastegate duty cycle data.

I think it gives an approximation good enough to find any real problems - i.e unfavourable pressure gradients in the exhaust.

Must be worth looking at this:

http://cgi.ebay.de/High-Flow-Facherkrumm...=item4aa952464d

The advertiser says "The AR-Racing-manifold has an inner diameter of 34 mm, enough for about 650PS. 34mm diameter are ideal for early response, without loss of final output. Especially suitable for big turbochargers!"

But not for external wastegate?

i mailed them a serious enquiry twice and got no reply so not sure what to make of them

Rob, could you check your pm please.

ok mate will do

funnily enough i have had contact today and they say they do a high flow manifold incorperating pulse technology built to high (german standards) with machines or some such..they are supposed to be exactly equal length..34 or 36 id ..interesting in fact so interesting i asked for one on approval!

The turbo question is quite interesting. The one I used although it was basically a GT3082R it had some key differences (and thus was a hybrid). It had the 4" T04S 0.70a/r compressor housing which means you actually have a reasonable chance of getting all the air in necessary and it had an interesting ported shroud which basically in laymans terms spreads the powerband meaning it spooled up earlier but ran out of puff later. I think a standard GT3082R would've started dropping off at below 7000rpm whereas peak power ended up being at 7700rpm or possibly a couple of hundred rpm higher (with race fuel it was above the 8000rpm limiter). So the turbo was really pretty close to a perfect match for the rev band.
It was an interesting contrast to the GT3582R I tried, because the turbine housing was smaller it was badly mismatched and power started dropping off much earlier. That tells you that in the Garrett turbos for the 2.4/5 to really shine you need at least a 0.83 A/R turbine housing.
It would've also been interesting to see what a GT3076R with a 1.06A/R turbine housing would do, when I originally had my 2.4 set up I used effectively a GT3076R but with a PT compressor wheel but because of the 0.64 turbine housing and internal wastegate the power peaked at a very low rpm - something like standard (5750rpm)

hi john, you are over your pm limit and i want to pm you if wouldn't mind..
do you remember how far you got with a standard manifold or did you never use one?
where did you see full boost? mines very low rpm 3200 which may be an issue,though that may be partially down to restrictive manifold so i am hoping with a good one it will be a little later
do you think you could have seen 600 from your turbo on pump fuel?(staying below 7800rpm) maybe doing things a little differently or do you think you had the most out of it?
i am interested to know what you think

OK not full any more.

I saw full boost higher than that, I got 1 bar at around 3200-3500rpm depending on gear. Obviously depends on what your full boost would be - mine was mapped up to 2 bar but I never used it other than to see what it was like.
I couldn't get 600 from pump fuel because the turbo couldn't do it based on the efficiency map etc. May have got a few more horses with more boost, but I only have the dyno run done at 1.5 bar boost which is the limit I wanted to maximise gearbox life.
I think also for 600 on pump fuel I would've probably been close to needing a 3.5" exhaust I would guess. My external wastegate was plumbed so I could either have a screamer or it go back into the exhaust. I never actually ran it as a screamer as I didn't want to burn up my car on overrun which I used to cool cylinders. Only the brave as they say....

i managed to melt the checker plating on the dyno with my screamer as i have it vented to a few inches above the floor..i was losing nearly 50bhp with it plumbed in..i am going down to barbz over the next couple of days so we can try out a experimental way of getting round my manifold issue, if it doesn't take us far enough i have to find one that will or instruct tigart on what i require and have them build one from scratch to suit the 2.5 though i am hoping they can do it without my imput

KTM you are over you PM limit as well

Not to hijack hence I tried to PM but what setup did you have that cost 50bhp? a plumb back in? but how far from the turbo outlet was the merge point? PM if you prefer

You dont really sound confident that tig art is capable enough to make what you need?

You have given them the input you recieved from the forum members to give them an idea what it should be i assume.

Regards and good luck,

Remco

news for those still vaguely interested..
the car is at barbz where he is fitting a standard modded manifold and a bit of kit we are hoping is going to make our life easy..we have a solution that as yet i think no one has used in uk.. we got it from usa and apart from a drag bike there is no other known use(we could find or any turbo company i spoke with whilst trying to buy one over here ,can find) of this set up.. so we may break new ground for coupe tuning ..the only problem will be the manifold..as yet we don't really know what its limits are..we soon will! whatever the car makes we will run it at that untill we can get a definate gaurenteed 600+ capable manifold built by whoever can gaurentee thiers will make the power..anyway this solution will be great for the 2l as it will give quicker spool than your standard set ups with far better boost control and allow the turbo to give its all without having to resort to a bigger housing...watch this space for results week after next..
on another note i have something to add to the debate regarding whether a 2l will be putting the same amount of gas through a manifold as a 2.5 to reach the same power..
ihave been speaking with a well known turbo builder/supplier who assures me they do not.. he went on to say he does a lot with subarus and when he puts a 3076 on a 2l he achieves 480 or very close everytime with his given set up..when he does same on a 2.2 he gets about the same usually a few bhp less but when he puts same set up on the 2.5's he struggles to get 430! but gets loads more torque as it chokes the turbo, when he fits a bigger housing then the turbo gives more the 480 as it can then flow the extra gasses..his words not mine..he thinbksd the manifold designed for the 2.l may well do 600 but with a 2.5 not as it caan,t shift volume of gas...can anyone explain to me whats going on in that real situation he comes up against every time he works the 2.5s? if they make same power with same gasses?

rmouthaan...i am 100% sure they can make what i need, thier fabrication and materials are top drawer but it's the design i am not sure on .. if i say just do what you think will work.. and it doesn't.. i am spending a load more money i can't afford to waste.. so it needs to be right ..unfortunaterly there is no concensus and everyone seems to have there own ideas..i am trying to absorb all i can so as to make descisions and give them some instruction..thanks for the good will.

I think you have answered your own question. He only swaps the housing to make the same power on a 2.5 litre - which also makes more torque. So, from what you have just written, the manifold MUST be able to flow 480BHP on a 2 litre, 2.2 ltre and a 2.5 litre as the ONLY thing he changes is the turbo housing.

you mention POWER, rate of doing work...

you don't mention revs ?

thus a larger cap engine will make more power lower revmlikem for like, thus choke itself higher up ? No ?

I agree, BHP is a measurement of power which is the rate of doing work. So, I don't need to mention revs as we are talking about a BHP limitation, not a revs limitation of the exhaust components including the turbine and housing. Though it is obvious that ALL OTHER THINGS BEING EQUAL a 2.5 litre engine will make the same power as a 2 litre engine, at lower revs. Having said that, the amount of fuel consumed per unit of power, and therefore the amount of air consumed, and as a consequence the mass of exhaust products per unit of power, will be the same for a 2 litre engine and a 2.5 litre engine producing the same power.

If this wasn't so, a 2.5 litre engine would consume more fuel per BHP than a 2 litre engine per BHP, so the BSFC would be 125% higher in the larger engine. This plainly isn't the case.

what i was hoping someone would explain was why the housing has to be swapped and why it cant make power with a smaller housing when a 2l can.. he hasn't got manifold issues so that wasn't my point

taz he did mention he works on some cosworths that rev to 9k and explained something relevent about revs which i have duly forgotten but there was a connection with the housing issue..
sorry not much use that i know..
we do have something up our sleeve that will be right up your street though..