16vt inlet manifold very restrictive ?

Well, I have always had doubts about the 16vt inlet manifold, unlike the 20vt it does a hard "gooseneck" turn into the head and looks very restrictivee but looks can be....

Anyway, a few have swapped to the grale inlet manifold for a gain of circa 15bhp (dyno Vas) which is a more direct design.

Anyway guy croft is building a grale at the moment and even the grale manifold is proving to be too poor flowing to match a standard un-ported 16vt head

http://www.guy-croft.com/viewtopic.php?f=10&t=2089

So the question is how much of the good porting work would be un-done by the standard 16v manifold? and who is going to build the first custom intake?

Whats Begbie done on his car - isn't that a coupe engine bay in the photos?

yeah - it is a coupe, it is Honza's NA 16v but that manifold is no longer available.

Not sure what Begbie has done, maybe he will answer, but this is the 16vt standard manifold (all credit to paddy 147 for the pic which google found)



and my Grale one I brought to replace it





so has anyone done any work around a different design and is it weakness link with this vs head work etc

So what is better then? The grale manifold or the 16vt stock?

the grale one is better than the coupe one based on my research but what the GC thread says is even the standard grale one isn't up to much. Vas runs the grale one and picked up BHP as the grale one doesn't have the narrow neck just past the throttle body.

From the GC thread

Standard 16v head flows 133cfm at 10"
Standard grale manifold 125cfm at 10"

and the coupe inlet is worse than the grale inlet but untested apart from dyno results (vas)

so it raises the question is head work a waste of time if you use the standard manifold

There must be some benefits to headwork as the port is not free to flow its maximum all the time as there is a big valve in the way. The manifold has no such restriction. At low lift I would assume the manifold could easily outflow the port and hence work to the port/seats/valves etc could still increase cylinder filling.

But it's obvious from the GC thread than there is no point developing the ports to flow 160cfm if you intend on using the stock manifold.

The integrale manifold isn't the best as you'll see but it can be made to flow better. Some serious removal of meat in the area near the gasket surface and a forming of at least a continual taper is possible. A suitable cross sectional area at least. You'd be amazed how much meat has to come out to do this.

http://i3.photobucket.com/albums/y85/1NRO/various005.jpg
http://i3.photobucket.com/albums/y85/1NRO/various010.jpg
http://i3.photobucket.com/albums/y85/1NRO/various002.jpg
http://i3.photobucket.com/albums/y85/1NRO/various018.jpg
http://i3.photobucket.com/albums/y85/1NRO/various031.jpg

I've built a custom manifold too, a whole heap of graft but fun enough to be making a small batch at the minute to a similar design but better still imo. I'm using the coupe runners for this next one as i like some features it has but no pictures of that for now. This is the one I made already.
http://i3.photobucket.com/albums/y85/1NRO/finalwelding001.jpg
http://i3.photobucket.com/albums/y85/1NRO/finalwelding016.jpg
http://i3.photobucket.com/albums/y85/1NRO/CIMG6529.jpg
http://i3.photobucket.com/albums/y85/1NRO/CIMG6526.jpg

If overal flow is your thing thats covered to excess but there is a fair bit more to it than that.

Nik

Saint already PM'd me last week about this. The manifold i'm using is the one from the Tipo, the swan neck bend isn't as sharp as the coupe one due to using 2 fuel rails (1 is in, the other is a return). GC did work his magic on the part that attaches to head and managed to raise the CFM up on it by quite a bit.

So best bet is to get a Grale inlet manifold and have it ported?

If you read Guy Croft's post, you will read he can't port it, as it needs to be split to be able to do this.

Surely if its that much trouble (and your not bound by race regs on use of OE engines) then it'd be easier to get in inlet manifold and runner purpose built?

Of course, but how much money do you want to throw at a one of a kind inlet manifold?

So best bet for a "bolt on" job having read the post would be to put a straight Grale inlet on and generate circa 15bhp?

No, it would probably be better to get the kappa 16vt inlet manifold

Not a cheap item due to bespoke hand made nature but not mental.

The Kappa manifold flows good enough for a ambitious engine build BUT it tunes at the wrong rpm for that kind of engine. You are afterall asking a lot of the 2 litre engine so rpm comes into play. It also has a less than satisfactory plenum volume and without modification won't accept a suitable throttle.

Sidedraft manifolds are available.

Fitting a sidedraft manifold and twin carbs was always the starting point when modifying older Fiat twin cam engines.

What sort of cost are we talking Nick?

Until they are finished and the costs are known I can't be sure, they'll be in the region of a custom exhaust manifold such as you know about.

Didn't know you were developing a batch of them. Could quite well be interested then.

you want to keep your hands in your pockets beggars and leave them there.

Steve has a point, you could use a GC DCOE manifold but have a plenum and TB made up instead of an airbox - the inlets would need bell mouths/radius entry (unlike this cr*p http://i208.photobucket.com/albums/bb91/.../Picture013.jpg)
, generally I liken it to the seirra cosworth intlet,
http://ferriday.co.uk/Cos_manif.jpg
The injector bosses would need to be added, and not have the TB's,

Alloy air box instead of this set up


oh and Paul, the tipo manifold I had was ported by GC, the same as Begbie's - its now melted down and used for coke cans I suspect.

I´ve found, that it moves peak torque of my engine from 4500 (standart coupe man.) to around 5500-6000. But engine could rev. happili to 8000 - wich was almost imposible with standart manifold. Because of lack of the air engine died before 7500rmp...

Now I am also playing with idea to create larger plenum - i didn´t measured the volume, but it seems that it is quite small (according to my rough calc .. 1,2l..) - in comparsion with similar manifold of S2000/1600 group or peugeot/renault sport manifolds... and general rules , that plenum should be at least 1-2times larger than swept volume..
some pictures of peugeot sport, S2000/1600man.

I'll send you some info when I'm getting closer to them being done.

"Steve has a point, you could use a GC DCOE manifold but have a plenum and TB made up instead of an airbox - the inlets would need bell mouths, generally I liken it to the seirra cosworth intlet,
http://ferriday.co.uk/Cos_manif.jpg"

bell mouths being needed is potentially something to expand on Rich, nice for sure but not the end of the road. I say they have origins in a search for the desired length of runner which inturn required them to protrude into the plenum so as to enable the unit to fit in the space available. A worthy compromise in this situation. That being said thats what i'm doing now as I know people want this feature, need it they don't in my opinion."

"The injector bosses would need to be added, and not have the TB's, suppose its similar to what Nik did."

Not far different to what I did, the biggest hassle was trying to balance the compromised location of the extra injectors. The Kappa manifold has it injectors pointing very nicely at the back of the valve so the secondary injectors could never be as perfect. An enthusiast machinist had the patience to set them up as close as we could fathom but still I'd look for improvement. I'd like to see how injecting the secondary fuel from a further distance might work, the 16v coupe runners lend themselves to this at the same time as having the longest SSR possible.

Nik

I have used the Kappa oneand got it modf to 8 injectors, and 88 mm throttle..
I know it can't match a custom made one.. but er see how far it can go.
i take a better pic in the morning

I can believe your results, right where I would expect the move in peak power to be for the length it is.
Plenum volume for a turbo engine is more about supplying demand, the 2 x capacity is a NA theory.
I like your link, I like collecting pics like that too. Here's a full on blinger for the collection http://i3.photobucket.com/albums/y85/1NRO/throttlebody-1.jpg

Nik

Nik PM sent

re. the last point, my target was to fit it in the space I had and thats the length of the manifold supplied by GC the AT bodies were as short as possible to clear the injector rail, and the trumpets were for a Px 600 airbox which is rubbish to be honest, the reverie one could take longer trumpets, even so they are still too short. It wasnt a road car and I wanted to get out on track hence drawing a line and not worrying about it. Any way GC said I can add length the other end e.g. the exhaust manifold side to assist with the tune.

here you go boys ...

http://www.amwdynoservice.com/page25.php?view=productListPage&category=14


and here is what you do to your intake :

http://kuvablogi.com/nayta/789163/

http://s224.photobucket.com/albums/dd72/jq4tm/?action=view&current=img789164.jpg&newest=1


this is the older version of that AMWORKS design plenum :

http://kuvablogi.com/nayta/789166/

http://kuvablogi.com/nayta/789165/

not going cost you too much, and will flow enough.. I think

here is an example what that kind of manifold does evo engine :

http://amwdynoservice.com/page17.php?view=preview&category=5&image=20

radiused belmouth entry, very similar to the inside of Nik's manifold which has radiused entry, thanks JTM

hi !


quite interesting thread....

so the oem grale inlet manifold flows 125 cfm at guy crofts flowbench.

but how are the differences between the cylinders ? any facts from guy croft ?

does every cylinder get the same flow or are one or more worse in flow ?


macki

no one ?

begbie, do you know the particular cfm´s of each runner of the grale inlet manifold ?
in guy´s forum thread only the overall cfm of the grale inlet manifold is mentioned....

the inlet manifold might be also a reason for the known heat problem of our 2l 16vt engine at cylinder 3 and 4 ?


thanks.


macki

I don't know each runner, and at a guess it would be a very close value as stated on Guy's forum.

Inlet manifold has nothing to do with the heat problem on cylinder 3 & 4, it will be down to the log manifold and turbo sitting by cylinder 4

Also note the cfm quoted is not a maximum figure in anyway it is the flow measured at a certain vacuum, to allow comparisons at the same vacuum to be made (i.e. against inlet port flow).

1NRO i just sent you a PM. I want one of those intake manifolds!!!

"The Kappa manifold flows good enough for a ambitious engine build BUT it tunes at the wrong rpm for that kind of engine. You are afterall asking a lot of the 2 litre engine so rpm comes into play. It also has a less than satisfactory plenum volume and without modification won't accept a suitable throttle"

Nik, you're a bit off the mark here. There are NO pulse-tuning effects/benefits in a turbo unit due to inlet runners (such as one sees on an atmo unit and which they depend on) when on boost (of any level) because the cylinder sees +ve pressure upstream of the valve as soon as it opens. And because the charge is being rammed in under pressure well above atmos they don't need any either.

The ONLY problem with the Kappa is that the runners are still a bit on the small size. It is however markedly better than the Integrale 16v and is on a par when modified to the (yellow) 16v Coupe one above. I don't think you're right about recovery rate in the plenum either. The plenum size is only an issue on change of state from closed to open throttle. Judging from test results I have of atmo engines the Kappa item is plenty big enough to satisfy the change-of-state on any liter and being pressurised in this application it will be better still.

GC

this is what I found to be different between standard 16vt manifold and grale one :

Runners are quite a lot shorter wich should be good for higher rpm power ( and loss for down torque )

after TB the original one have first bottleneck, it has much smaller hole, than grale one..

cant remember the measurements anymore but overall it was something like 20% smaller hole on standard 16vt. its because of the manifold shape.

On a turbocharged unit the runner length is only relevant in terms of the viscous loss!

G

but what about the size of the hole ...

??

that should matter... ( size does matter )

JTM you idea of a bottle neck is probably capable of flowing more air then the engine is likely to need for road use even tuned.

Hey Guy, in one of your threads you mentioned chord/diameter ratio. What does that mean?

This might help, Clicky

Hello Guy,

Good to see you here, a place that can benefit.

With regard to there not being pulses within a forced engine inlet I can't agree. Am I right in understanding you are refering to the higher density of the medium (air) causes the pulses to cease to be?

Will a very efficent NA engine pull + pressure at IVO? Is this not the same but less prominent?

I'm trying to get the density influence clear in my mind. Casting thought to a natural example is the wave/pulse, whatever is best to call it, created by a tsunamis not passing with force across whole oceans through a far denser mass?

I can't for the life of me see how they would stop when above atmo.


Nik

i took some measurements on that bottle neck...

hole after TB is 63mm x 63mm ( 2,5" )

but in 16vt it goes right after that to size of

63mm x 46mm ( 2,15" 54,5mm )

so its a little smaller, than our standard TB is

Cheers

Nik, a negative wave from the cylinder (at depression) is reflected as a pos wave where it sees high pressure, which in this case is immediately at the non-firing side of the inlet valve not the plenum - as would happen on an atmo engine.

G

chord rule:

http://guy-croft.com/viewtopic.php?f=6&t=2110&p=11022&hilit=chord#p11022

Guy,

My understanding is that the pulses/waves created by flow accelerating/decelerating due to the PD are not influenced by changes in pressure like you say. If this was the case there would be a massive jumble of waves even in a NA engine from every small change in pressure within the port (non-firing side). The pressures as you'll know vary within different areas around the port/intake runners.

My opinion is that waves reflect at abrupt changes in area (when it hits the plenum for instance). As you say their origin is initiated by the PD and then the IVC creates no area which would see the wave traveling in the same state as it arrived, no matter the pressure, until is next meets a change in area. The density change in the air influences the speed of the waves IMO so there is a difference but they don't reflect off the PD.

I know it's not something you care for but forgive the link, I find it excellent on this subject. http://www.sengpielaudio.com/calculator-speedsound.htm

If I might mention the size of plenum and the influence on this subject, a bigger than usual plenum, from my research, allows a steadier flow without too harsh a change in pressure.

Nik

Should be getting car back at weekend... Inlet manifold has been ported to max gasket port size but thats it! I'm hoping to see 350 plus bhp but am a little worried by this thread as it seems the coupe manifold is so poor? Nick

Good thing you have brought this back up, i've read something where someone has taken a coupe inlet manifold and an integrale inlet manifold and stuck it on the flow bench, the results? Both flow the same, so there is no difference in swapping the manifolds

yes there is a difference ..

at least the grale manifold is 2.5kg lighter

and injectors are better to be seeing ( for chancing etc )

does someone have flow results ?

my next manifold is going be the wrc double style plenum, thats for sure .

Ok There is that (lighter and easier to change the injectors), but there isn't any flow results, but would guess it was similar to the tipo inlet manifold i have

Any links - Vas, if I recall correctly had before and after dyno results for the grale manifold but it could be the difference (10-15bhp) was within the margin or error for the dyno and the difference in the days - ie could have been cooler more humid etc

:-D Fantastic news beggars.... I'm a lot more confident now of reaching where i want to get to.... Should have some dyno figures within the next 14 days! Nick!

But didn't Vas do some minor mapping tweaks as well?

Link is http://deltaparts1.blogspot.com/

That's a deluded patter writen by someone who doesn't know what he's talking about, when you tell so many lies you start to believe yourself.
One minute talking about 28" and then quoting numbers related to 10" with a thinly veiled theft of numbers from elsewhere and some stupid wild claims in amongst a script designed to reel in those that know no better.
If there was even the slightest understanding of the potential performance from given numbers there would be no mention of silly big valves, a standard sized valve with correct port dimensions is capable of supplying enough air to take the rpm's to crazy levels. The reason for equal length manifolds is nothing to do with flow levels, just sounds fancy though doesn't it?
If it was about cfm we'd be hacking heads as big as we could, this is not the case in a correct job.
Don't be lured in by the patter, you can be sure it's misguiding.

The problem with any of the manifolds (the two coupe ones, kappa and integrale) is that the minimum cross section of the runners is some way off suiting the head. This is the case even with a standard head but start working the cylinder head and the restrictive part that is the inlet manifold just gets steadily worse. They can be eased and improved to a point but the likes of the plenum part and the integrale one have areas that just can't be accessed with the grinder so the fundamental restriction still remains. The coupe one having the rubber jointed sections allows better working and the bit that joins onto the head can be ported to some very suitable dimensions. Takes a bit of doing though http://i3.photobucket.com/albums/y85/1NRO/inletmanifolds033.jpg

well my inlet has been ported where it joins the head but no work has been carried out on the parts shown in the pics..... seems there would be a massive gain there, looking at the 2 ports next to each other......
well one thing i know now is that my inlet will flow in excess of 360 bhp as i know vas was running around 350-360 with the grale manifold... and i don't think he even ported it!?
(Thats if the flow testing on that link is accurate.... LOL)

NICK

I needed a turbo race engine and for reasons of cost I originally started with an 8 valve 2 litre Lancia turbo engine. For a plenum/inlet manifold I selected the one designed for the Thema but for a number of reasons it doesn't work too well. The torque curve is heavily influenced by inlet tuning and the Thema plenum/manifold gives peak torque at around 3000-3200 rpm and then works quite well up to about 6000 rpm after which it becomes seriously restrictive. This is largely due to the relatively small cross sectional area of the runners.

Having decided to build a 16 valve engine rather than chuck more money at the 8 valve engine to get the power I needed, I was concerned that I didn't end up in the same place - with a stock manifold that was too restrictive. This 16 valve engine will need to rev to make the power it is designed for and the wrong manifold will strangle it.

The Kappa manifold seems to be the one most commonly chosen by the Lancia drag racers on the continent but rarer than hens teeth in the UK. In any event it was bound to be a compromise in some area of it's design - either runner area, runner length, injector location or installation was likely to bring some problems - so I decided to design and have built a custom plenum.

With the aid of Engine Analyzer Pro I was able to simulate the whole engine, exhaust and turbo and ran multiple itterations of the inlet runner diameters and lengths until I found the 'best match' for our cams and timing.

I would like to confirm at this point that inlet pressure wave tuning is as fundamental to the correct design of runners on a turbo engine as it is on a normally aspirated engine; anyone who says otherwise has either not done their homework or has no personal experience in this area.

The inlet manifold design I settled on gives a 5.4 psi boost immediately behind the inlet valves at 5000 rpm - that is either on top of atmospheric pressure if running N/A or off boost - or on top of boost pressure when running flat out.

This 5.4 psi of boost costs nothing - it brings no additional need for intercooling with it, for example.

My design brings no increase in inlet pressure below 4000 rpm, but that is more down to our cams than anything else. At 4000 rpm is gives 4 psi, peaks with 5.4 psi @ 5000 rpm, gives 4.9 psi @ 6000 rpm, 3.3 psi @ 7000 rpm and 1.8 psi @ 8000 rpm.

The cross sectional area of the runners is 1590mm^2 - the equivalent of a tube with an ID of 45mm. The runner length (head face to plenum) is 200mm. Shortening the runner length from 200mm to 175mm reduces peak torque and pushes peak torque up 500 rpm to 5500. It also extends the rev range to 8500 rpm. None of these effects was desirable in my application, so I stuck with 200mm.

If someone could tell me how I could post a picture of the design and if anybody would like one for themselves I can put you in touch with the company that made mine.

Go to photobucket.com
Register an account
Upload photo
Get the link to post the photo
Then post on here with:

I couldn't get that to work so I have posted the link instead - hope that's ok.

http://s977.photobucket.com/albums/ae255/group5lancia/?action=view&current=Plenum1.jpg

Looks like you made that in CATIA V5 etc.....

Fixed it for you. Very nice looking inlet manifold. How much did this cost to get made?

B its a CAD drawing

Not cheap I'm afraid - £750 was the final quote which is cheaper than my exhaust manifold - but it was the first one so copies might be cheaper. However, as the head would not flow what I wanted without the proper inlet, what choice did I have but to do it properly?

The curve in the runners is to suit my installation. These could be made straight or curve the other way, and injectors could also be relocated.

Literally hot off the press and will be installed next week, so pictures (photos) to follow.

Any pics of the real thing?

As I said above, it has just been finished and will be fitted next week, so I will get some 'real' pics up a.s.a.p.

that looks like a brilliant bit of kit there!

cant wait to see the real thing!!

I know it is, still a very nice looking manifold

The design was inspired by this LC2 setup

Nice work. I love the Lancia LC2's (infact anything with Martini livery.... )

That's a pretty drawing, must be to fit the coupe engine bay? Your running a coupe or a lancia?

I'm suprised to see the cross section is as much as it is. You must of ground a lot out of the cylinder head entrance or maybe the manifold runners taper down smaller near the head? Have you a throttle in mind to use? Sorry for the questions, just a favourite subject of mine.

Nik

I have 36.7mm inlet valves, giving a valve area of 2116mm^2. The inlet ports are 27mm diameter at the narrowest point, giving an area of 1145mm^2. This size was chosen to match the peak RPM the engine will be run at whilst keeping good gas speed at lower RPM. From the narrowest point to the head face the ports increase in area to finally match the inlet runner area.

Peak flow is 182cfm @ 10" of water (287cfm @25", 304cfm @ 28") with the valves in. This is an improvement of 143.5% over the standard head, with measurable flow improvements from 2.5mm lift. I haven't yet measured flow with the manifold on but EAP says all will be fine with an actual total engine flow of 646cfm @ 8000 rpm @ 29psi boost or 574cfm @ 8000 rpm @ 21psi boost.

The engine is fitted in a Lancia, but the runners could be re-designed and the throttle body position modified to suit a Coupe I am sure.

Yeah, of course you have

Not sure if there was a hint of disbelief in the previous post, but here is the comparison from the flowbench

A pretty graph isn't going to win me over I'm afraid, you'll have to do better than that.

The big valves is interesting, any chance you might explain how you went about fitting these?

That is your choice, of course. I don't have anything to prove here - I'm just trying to help those who asked, including the OP, about dealing with the flow restrictions of the various standard inlet arrangements.

As for fitting the valves, you can get in touch with Automotive Machine Services who did the work. I have sent you a PM with contact details. All I can say is it wasn't a big job - new seats required of course and also for the exhaust valves which are 32mm. The 36.7mm valve is only 1.15mm bigger in radius after all..... oh, and I forgot to mention the bores are 86mm

2mm over bore?..... Isn't that ALOT?
Mines just been bored to 84.5mm, which makes it now a massive 2.02 cc engine.....

Nick

I agree. I have 85mm bores in the 8 valve engine and I thought that was on the limit. But the 86mm was specified and machined by 'the man' and he also supplied the CP pistons. I know it's not the only '2.1' block he has done - so who am I to argue? Block is Fiat Croma which might make a difference...

I can't help but think that the respected Guy Croft who has put a fair part of his lifes energies into the Fiat twincam might have a decent handle on how to extract CFM from our cylinder head. He has afterall done many of them to all levels of performance. I know him to not be a bull shitter in any way and have not the slightest doubt that he has done everything he could to get the most. Below he talks about just this subject and you might do well to read it. Whoever is telling you those figures is having you on. To do it with a pinch point of 27 mm is fantasy. As you'll likely know Gregs car is no slouch with a power level that is amazing, all on a standard valve size.

http://guy-croft.com/viewtopic.php?f=13&t=80&hilit=greg

The simple fact is the standard valve size on a decently worked cylinder head can supply enough air to maintain 100% ve at incredible rpm, peak potential VE happens lower still.

86 mm bore is asking for trouble too, at the level I think your shooting for you'll be needing all the rigidity you can get, those rings will be struggling as it is.

Is your manifold (inlet) to be exactly the same as the drawing? Looks to me that the air flow at the transition into the cylinder head is going to be nosediving into the port floor.

Pictures would go a long way to proving what you talk about, I'm happy for you to push boundaries (I like to be this way too)but sometimes some things just aren't worth the expense or effort but I'm sure there's plenty who would like to SEE what you've been up to.

Nik

There is, I think you will agree, a huge difference between the head on an 8 valve twink and the 16 valve engine. The only true similarity is that they will fit on the same block.....

In this case, GC supplied and bored the block and provided the pistons - all his spec, not mine. If you think it's asking for trouble, kindly argue the point with GC, not me.

GC also supplied the head fully prepped and assembled by his own hands with his own inlet valves, springs etc (flows shown on the lower trace). GC has not fitted the larger valves nor been involved in the additional machining and porting. GC has said on his website that the Lancia/Fiat head can flow as much if not more than any other production based 16V head, possibly with one or two exceptions. Take a look here... http://guy-croft.com/viewtopic.php?f=9&t=98

I have 13.8% more valve area, so 160cfm x 113.8%=182cfm - exactly what we have achieved.......

Though they are pleasing (to me) I don't think the figures that have been achieved are that extraordinary compared with what GC has produced from the XE and other heads. Neither are the port sizes in the least extreme for an engine running to 8000 rpm. And as for the valve size, as I am sure you won't need telling, what a larger valve allows is better breathing at all lifts and all RPM - not just peak RPM. This is what makes for good torque - as again I am sure you know. With the standard valve there is a mis-match between the valve size and the throat - the throat is too large for optimum performance with the standard valve as I am sure you and GC are aware of. This has been verified by several other independent experts - but I won't name drop. Rather than add metal to the throat we decided to enlarge the valve to match the throat. Simples. The preferred port size to match the valves is somewhat larger, but as we are looking for peak power at somewhat less than 8350rpm we have kept the size down to 27mm.

As for the manifold, I assure you that the angle of the inlet runners is perfectly inline with the angle of the port looking directly at the back of the valve.

As for proof of anything - well, as I said earlier - I am here to offer some answers to the OP and a possible alternative for those looking for a solution to the inlet dilemma. Prooving will be done on the race track. It's the only place that matters.

That's interesting to hear the source of your engine, not at all what I'd expect of Guy. You'll have to keep us updated on results.

I am suprised at the throat size though, some 6/7% away from becoming a burden on lower rpm torque imo.

I guess it depends on what RPM you are talking about - so what number are you working to?

New pics - and a comparison (angle wise) with the Kappa manifold - which has a straight shot to the back of the inlet valves.



Glossy!

And matching cam cover....

I look at the minimum cross section as being more to do with the bowl and valve size rather than rpm. The length of runner has more influence on rpm imo.

Your manifold certainly looks glossy, I like a bare alloy myself but each to their own. Maybe when I've finished them I can offer you an upgrade on what you already have. Aimed at a very similar rpm to yours and certainly not going to restrictive, if your running by then (it'll be a while yet) a bolt on test would be interesting for you I'm sure. Are you running the power steering pump in the integrale position? A taster of what the air will see on it's way into the cylinder http://i3.photobucket.com/albums/y85/1NRO/inletmanifolds016.jpg the rings are to be pressed and dressed onto the runners once the plate is welded to the runners. There's to be an injector mounted in the lower plenum above the bell mouth and a diffuser system between the two.

Have you a particular throttle size in mind to use?

Yours has very short runner lengths - why is that?

It looks pretty solid and bomb proof though - what is the finished weight?

CL comes in at 175 mm

Forsure it's heavy duty, I don't know the weight as it's not finished yet but the attatchment for the or brace is there so no worries on that front.

What size throttle are you intending if I might ask? Also are you running the integrale power steering pump?

What cam duration and timing is the 175mm tuned to work with, and at what RPM?

I don't have power steering on the race car. I have three TBs and will be selecting the best option on the engine dyno.

Depends on who might buy one and the nature of the engine they have/are building. There's a number to choose from and custom also.

No power steering! What's the car?

I thought maybe you'd have a theoretical dia TB, in such a carefully simulated engine.

160cfm x 113.8% = 182cfm

At what pressure ratio?


GC

182 cfm @ 10" water
287.8 cfm @ 25" water

Sorry but you'd have to take so much material out of the ports you'd be working in thin air to get that from the 16v. You can't just ratio up the BPF because the valves are bigger and assume the flow will go up, the controlling section isn't the valve throat it's the splitter bore.

GC

I agree it's not the valve throat controlling the flow. As mentioned above, with the standard valves fitted that area is a fair bit larger than optimum. The main reason for increasing valve size was to optimize the throat/valve area ratio.

It has been achieved, and the measured results come from a Superflow bench. The figures are not BPF - they are valve in at 10.8mm lift.

The unmodified head flows correlate 1:1 with your figures, the modified head/standard valve flows correlate 1:1 with your own figures, so there is no reason to doubt the flows figures measured by the bench with the larger inlet valves, with the controlling sections of the ports modified to match. I am sure you could achieve the same. Why not give it a try?

Something wrong with your flowbench, Mr Kift.

GC