Lag + Power Vs Spool up, Less power

Ok your personal views experiences would be good.

Anybody who has fitted a Gt28rsr/or gone for the bigger turbos` your views would be ideal,would you go for your choice again or change......Nigel,Flea etc etc

Just to cover all angles, I was thinking about going 2.4,I have the price for the stroker kit, but no idea as the cost to what else I need..e mailed Barbz but still waiting on a reply

My Gt28r started to smoke so i sent it away to Turbo Dynamics and got myself a nice new GT28RSR but I now want to fit forged rods(something I should have done a the rebuild but never...plonker)so this now gives me the chance to fully exploit all the mods I have by not being restricted by the OE rods

So now....

I`m not sure,if I should fit my new GT28rsr,get it mapped and see what I get with the current mods I already have.

or go for a bigger turbo and therefor more power..... but more of the dreaded lag

I`m not going to use the coupe on the track, just want a fast driveable road car (not used as my daily driver any more tho`)

current mods as far as I can remember ..

C+B cams
stage 3 (so I`m told ) headwork
Aquamist
Forged pistons
shot peened/balanced rods..changing for forged
lightened flywheel
all balanced
chargecooler(for sale soon tho`)
blueflame Exhaust (soon with 5 stud downpipe)
fully ported opened up manifold
Apexi boost control
FMIC
SIP
GTech2 or Squadra chip ...can`t remember
uprated fuel pump with wiring mod

I reckon I will need bigger injectors, but will decide when I decide on which turbo..

will add if anything missed,if and when my brain works

just incase anyone mentions it,brakes,suspension and lights already uprated

Im only speaking from my own experience, but i think you shoudl stick with the rsr and get 370bhp as markus did.

Ross

thanks h2yper it`s personal expreience that counts it`s great to say my coupe has over 400 bhp but it`s how it drives that really matters ,BUT ........................................




having over 400bhp sounds good to

Its the reliability tho aswell. You've had nearly no problems with your other setup.

Ross

p.s. you have pm.

RSR Paul, you know it makes sense.

Yup I have been spoiled,I have had no problems at all with my set up

that s 2 votes rsr

Hmmm, I was going to suggest GT3076 and let me dispose of that useless RSR for you.

RSR. In Nigels other thread he said he felt he went too far with the turbo, and I'd be wary of sticking a massive turbo on if you're concerned about lag.

I'd go 0.86 Disco Potato.

I think with extensive headwork and ported manifold you won't suffer from too much lag. If you're using standard injectors I would also throw in a bigger FPR to help get more fuel in there.

Also with a balanced bottom end you could run a higher rev limit hence keeping the same powerband.

you need to drive a couple of cars - one like mine with some lag but a mad top end and one with loads of low down pull, but less urgent towards the redline

There are times when my car annoys me, booting it at 2,000rpm and waiting for a long weekend for the boost to arrive.

Other times its just sooooooo much fun, like sitting in the outside lane of the motorway, waiting for the muppet in the BMW 325/330 etc to pull out of the way, then howling past like it was standing still, or like tonight, coming up behind a Bentley Continental GT - he floored it, expecting to lose me - he didn't (in fact I had to brake to stop myself leaving a Plus grille effect on his precious Bentley ar$e)

would be ideal,buy can`t happen `up here` so will just have to think long and hard,my brain says, rsr `you know it makes sense`....but then,I think I could have around 450 bhp to play with and i think sh*t need to decide,as i want it back on the road now

Paul I thought you often came up to Aberdeen? If so you're more than welcome to drive my old rust bucket, see how you like the RSR.

i think you are in exactly the same predicament as me! i really don't know whether to just stay with what i've got and maybe some headwork, or go the whole hog.

i'm swaying towards staying just below 400bhp and having a much more driveable car and it seems to be a lot less hassle. i don't know if the hassle is worth it!

Mark

Matty, thanks for the offer,yes I used to be up a lot, a good friend of mine owns a few clubs pubs up their,but due to me buying a new business,Ive not been able to get up in ages ,hopefully, I`ll rectify that soon, if so i`ll be in touch
Mark ,one of the main things that is pushing me, is I am going to fit forged rods ,which will give me the capability to really push the engine,and I feel maybe I should take the opportunity to do that.....but well hmmm
tbh I am kinda swaying towards the rsr,with my spec it should give around 360-380 still be a plenty fast coupe,but 430 or so sounds damn good too,but will it be a pain too often, as Nigel mentions........until you get a piece of road to use it .......then ...it`s make your mind up time

You could leave it as is, and add 4x4 from a dedra integrale or 155 Q4. You get to put all the power down, great traction and handling - the best mod you can ever make to a coupe. Very very nice indeed.

Jowster,looked at that years ago with Barry at EVO Engineering (when Barbz was still with him)not as easy as it first sounds ,but would be great fun, if done,especially with 450 bhp

Paul, if you can make it to Crail on the 11th Fergie will be there with his which is powerful but a bit more laggy and Matty should be there too so you can see what the RSR is like.

How much difference is there really tho? between 360 n 400? Its not gonna be noticeable on the road really.

Ross

Paul. Already done this using dedra integrale - but not on a 20VT:-( That's the project for next summer. Traction was the best.

Back to the turbo, GT28R more than enough....as the advert use to state "power is nothing without control"

It is a little bit like diminishing returns - but I bet you can remember the difference between your std car and it with a GTEC or something like that, and that is the difference in power.

+1

I'm currently driving with 1.0-1-1 bar boost (waiting to fit 500cc injectors and reprogramming the thing) and that is 300bhp. I can tell you I can feel the difference to last weeks 330bhp

V.

I'm going forged aswell Paul

Going forged seems to make you feel that if you don't push the engine further you are wasting the money that you have spent

Yeah but i think thats got something to do with the way the power was delivered after the gtech. Going from a 360 beast which would be full on power, to 400 which is still full on power..... Dont know if there would be.

Ross

I would say go for more power. As long as spoolup wont be much later than 4000rpm.
I really dont understand having a lot of torque at 3000 rpm on the coupe. If you need the torque, just shift down.
If you want to go fast and get good acceleration you need the torque higher up.
If you want to cruise around town and listen to music with a big spoiler back. (And maybe a few of those cool stickers and neon lights) Then get the torque low-to-mid range.

Lol. Good to see you dont have any strong opinions

Maybe some people like usable power. Maybe people dont use the coupe as a toy, as it tends to not respond to a ragging on a constant basis.

Ross

am I on the correct forum !!

Why is power non-usable just because you use it on a lower gear ?
I dont see running 50mph in 2nd gear as a problem. (When I need it)
Having torque low end is what I would like to say non-usable power. Because its outside of the coupes rev range. (Wich is between ~4500-~7000) So basically you just throw the power away.
But sure, if you dont like shifting - why not.

Man you talk rubbish. The stnd coupes power range is between 3000-6000rpm. The stnd car is very driveable. What you intend to have is spool up worse than Nigel and Flea, who would both agree that as a road car, the power should come in earlier.

Paul does a lot of motorway miles, as do i, and changing down into 4th at 80mph, just isnt an option really. Would prefer to squeeze the throttle and the power come in.

What torque would be good for good acceleration in your opinion?

Ross

There is nothing rubbish about what i'm saying.
If you dont believe me. Go out and test your car. Go into 2nd gear and give full throttle to 6500rpm. Then shift to third and tell me what rpm you have then. It wont be 3000 rpm, no it will be above 4000rpm.
And then go even higher! 3rd gear to 6500 rpm and then shift! Where will you be now? even higher.
If you want to have torque at 3000 rpm and shift at 5000-5500 rpm then sure do it. But you will loose a lot of top speed.

Or why not let us do the math!?
Gear ratios of the 20VT.
1st: 3.800
2nd: 2.235
3rd: 1.520
4th: 1.156
5th: 0.914

1st gear at 6500 rpm switch to second -> (2.235/3.800)*6500 = 3823 rpm.
2nd gear at 6500rpm switch to third -> (1.520/2.235)*6500 = 4420 rpm
3rd gear at 6500rpm switch to fourth -> (1.156/1.520)*6500 = 4943 rpm.
4th gear at 6500rpm switch to fifth -> (0.914/1.156)*6500 = 5139 rpm

Wow what have ve learned? That even from 1st to 2nd gear you will be closer to 4000rpm than to 3000rpm.
and as we go faster our "low-end" torque just becomes more and more useless.



As I already told you. a Torque band between 4000 and 7000.

didn`t know my coupe revved to 7000

I hear what you are saying,but it is a simple fact,the more you push the power higher up the rev range the less accessable/useable it is.

One of the coupes strong points, is the fact it has fairly good torque low down, and all thro the rev range,i want to keep my torque curve as flat as poss, but with as much power as poss, from as low as poss.

It would be very easy for me to bolt on a big turbo and get almost 500bhp but I`d have no low down grunt at all...................
I don`t think that would make it

a/ a very fast road car and
b/ a nice car to drive

I would be happy to say my coupe makes over 450 bhp,but not if i have to rev the nuts off it to find the power

I really dont think you get my point.

(7000 rpm is because people who tune will probably raise the rev limiter a bit - most chips do)

Please tell me why it is so much worse to rev 6000 rpm than it is to rev 5000 rpm ?

Why wouldnt it be a fast roadcar? maybe it would be a little slower in first gear between 10mph and 20mph, but do you really need to go that slow?

I dont think you understand that it doesnt matter what kind of torque range the engine have unless its geared for it.

The only thinkg you really do by moving the shift points lower down the rev range, is that you lower the speeds at wich you gear. And in return you loose top-speed.

No it wouldnt be easy. Not if you want to keep the torque band between 4000-7000 rpm.
(Sure you could get 500bhp with a big big turbo and torque starting at over 5000, but that would make your car pretty slow and inefficent because you cant rev to more than 7000)

At those powers the deal is not just about switching turbo and have a lot of power. To get a bigger turbo to spool up as fast as a smaller turbo. You need a more efficent engine.

People on this forum get to that point in two ways.
Some alter the cylinder size. (The "easy" way)
Other start porting and matching and play with different cams etc. (the hard way)

And some do both ;-)

With all due respect you're wrong.

A turbo doesn't spool at an arbitrary rpm. On higher gears it will spool up earlier, so the forum uses pretty much spoolup in 3rd or 4th as reference, so if a turbo is fully spooled up by 4000rpm in 3rd you will go off boost switching up between 1st and 2nd. Or at least you will be in the rpm range where the turbo is still spooling up and so you will hit a flat spot between gears.
Trust me I used to have a turbo that spooled up at 3800rpm in 4th but 4300rpm in 1st and about 4150rpm in 2nd and unless I changed up within 200rpm of the std redline it would drop off boost.
Plus if you have any sort of wheelspin in 1st or 2nd when you change up you will definitely go off boost because the revs on the rev counter will not reflect the revs as delivered to the tarmac.

Fuel, by you going into gear ratios and this and that your WAY off the mark again.

Paul doesnt drive around in 2/3/4th gear most of the time. Also who wants to be driving on boost with a big turbo at 4000rpm in 2nd gear? The characteristics of the larger turbos is a severe kick in the arse. Smooth power delivery available on tap is the setup that Paul wants (and myself really).

Regardless of what revs your gonna end up with when ya switch down, your still having to use the high end of the rev range.

Btw if i wanted to know the torque band you'd think was ideal, i would have asked. However, i was more interested in the actual figure you would deem to be good for acceleration. From what i know about Paul's car from Barbz, Paul could EASILY get any high end figure he wanted from the 2 litre, because of the extensive headwork on his car. So he could get 450bhp with spool up *around* 4000rpm.

Whether he wants to drive to an ON/OFF car is the question.

Ross

yes I feel that way too,but due to work load just now,no further forward tbh.



I might just invest in a second turbo,and have 2 live chips written, one with the maps for rsr, and the other mapped with a bigger turbo,then I can have both.....

not fast enough !! change the turbo and chip.........

to much lag, change back

JohnS: Correct. But in what way does this make me wrong? I never said "Get a turbo that has full boost at 4000rpm in 3rd gear" I said "get a turbo that doesnt spool up much later than 4000rpm" And by that I mean in any given gear. (If you however have full boost around 4000rpm in 2nd gear you're pretty safe for the rest of the gears)
Wheelspin in 1st and 2nd gear is not really a problem since it can be eliminated with good software. (mapping, traction control etc.)

I myself have a "bigger" turbo. With spoolup around 3800-4000rpm. And I can say that even with those rpms (wich you think are horrible) im wasting a lot of low end torque.

h2ypr:
? If he wants to drive around and cruise in fifth gear at highway speeds it wont be a problem. I really dont understand what you think the problem is here.
There is nothing ON/OFF about a larger turbo, you just move the torque band.
I think what you are after is a car with 1 gear wich will always have quick response. The way combustion engines work right now this is not possible. (Not unless you want to sacrifice acceleration/topspeed - maybe on cars with electrically controlled valves)
Electric cars however, have this kind of torque delivery (constant torque) and dont need any gears. Hopefully we will see a lot more of those soon. (Tesla roadster)

How much xxx BHP paul can get with his mods are pure speculations, all im saying is it wont be a "walk in the park". And if done right it wont be an ON/OFF car as you describe.

And by the way, gearing is probably one of the most important things to think about. Even with an engine who only has a torque band between 3000-3100 you can make it fast. (continuously variable transmission)

It is the compromise between flexibility and outright power. If you look at rally cars they have a reasonably wide power band and that is because there are situations where it is better to utilise the current gear rather than change down etc.
In general you can measure flexibility by calculating the areas under the horsepower graph. The greater the area the more flexible the setup. Flexibility means it can perform well across the range and for everything except straight-line dragging I think it is important.

Just wana comment something here..i have a GT28R and im suffering form the turbo lag!

If I floor it on first up to red line and I drop it to second, the car is feeling lazy until it reaches 4800-5000rpm! During that short time any car could pass me! I have tried to do as much as I can to reduce the lag, but it seems that no way to do it. (check my graphs here )

I would agree with john, that I would get the boost in 3-4 before I see it in first and second, maybe its due to boost controller or something but it annoying me. TBH many times am thinking to fit superspool or hybrid to improve the spooling.

What I want to say is that its important to reduce the lag and have the power at te same time get compromised solution, but just don’t drop any one of them.

omran

If you want the best of both worlds, you need to go for a different ECU. One from Omex or DTA will allow you to fully map the fuel, ignition, build in traction control using the ABS, limit the boost in 1st and perhaps 2nd, and allow a much greater control then a standard ECU which has been mapped. Omex for example allows the use of a bigger Turbo, and with enhanced head work etc, can even incorporate launch control and have anti lag as well.
Why you guys insist on keeping the old ECU i cannot understand. Spending so much money having your engine built with forged parts and heavily modified engine parts, this will limit its potential. No matter how good you map the original ECU [even with a chip], it is always a compromise somewhere in the rev range.

Andy.

Good point Andy.

We can actually get very close bhp figures for my engine with a gt28rsr or a few of the bigger turbos, solely because it has been done before,so in this instance we do have a very good indication of bhp figures.

I don`t want a power band that starts at 4000revs + ,no matter how it is put, it is not as fast on the road as an engines who`s power comes in at say 3000rpm,unless of course you drive around in a gear lower than you would normaly need, or be prepared to change down every time you wish to be in the power band,do you drive around with your engine spinning above 4000 rpm all the time ?

For instance,on the new 997 GT2 Porsche has worked hard to get peak torque from 2200 rpm to 4500,which helps to make the thing so rapid,squeeze the throttle and your off,not squeeze, wait until you get past 4000 rpm, and then go, or have to change down all the time...............buy a Honda for that

Yes, I do agree with the correct gearing, you can then alter every aspect of how the car will respond/behave,I am not in an economical position to do that,or fit variable transmission.

It`s down to trying to get the best compromise between outright bhp and driveablity,and having all the power above 4000 rpm just does not cut it for me,also heat+high revs are a big killer for any engine,so 7000 rpm, I don`t want to have to constantly be their, to go fast.

Fuel have you got a Fiat Coupe ?

Paul - Slight point about the GT2, it uses Variable vane turbos, so can allow boost from very low down, where as we cant

With Omex for instance, you can have a switchable map, so it can run several maps. Just have it at a flick of a switch.
Even the standard Turbo is more then a match for the standard engine. It can provide boost to over 300bhp easily. Its how the engine uses the boosted air mass. Making the head more Volumetric Efficient is the key to good reliable power. Just bolting a big Turbo and chipping the engine, and hoping for the best is a recipe for disaster. A few members on here can adhere to that !!
As for revs, OE rods are good for around 7500 revs max. Forged are required for more revs. Also because of the way the crank rotates the rods, you need to be careful how you build the bottom end.

Andy.

JohnS: Yes, this is a good cause for torque low-end. Rally cars however as you describe it make the band "wider". Not loosing high-end torque. A wide band is always good, this is not the cause here though, since by making the coupe have full boost at 3000rpm you move the band lower down. (not making it wider)
You tradeoff high-end torque.

Omran: After watching your torque curve, you seem to have peak torque around 5500rpm, and a big drop earlier. This makes you way of band and thats why you're experiencing bad acceleration/driveability.
I really cant see the boost curve so I cant comment this any further. Your car will probably be a lot faster after you fix this.

sumplug: Very very true. People can have the best hardware there is, but if there is nothing to control it reasonably it wont be noticeably better then a std car.
With good software you can adjust the ignition curves better when off boost and kind of remove the "lag feeling" a bit.

paul:
Maximum acceleration is always obtained when the torque at wheels is max.
Torque at wheels will always be larger on the coupe at lower gears. So even when you have torque low down and dont have to shift down when at 3000rpm - a car who has torque range higher up and does shift down, will leave you behind because it will have an higher average torque at wheels.

Yes. I have a coupe. A 16VT.

No I don't run at 4000rpm in 2nd gear when I dont need it, if im just cruising around im almost always at 4th 5th gear at almost any speed. When I want to have fun I downshift, turning the rather silent car into a race machine.
If im racing, I keep gears low and revs high. Wich gives me instant response and great acceleration.

Nope, you cannot have torque at both ends of the rev scale. Torque is measurable under the torque curve. Its the duration and lift of the cam[s] that determine your torque curve. Remember on a 4 valve engine, air velocity is low at the bottom end against a 2 valve engine due to the valve size. A turbo helps to increase the velocity but the static compression is low. Until the air is boosted, the measurable dynamic compression is low, then shoots up when boost comes in, velocity shoots up, torque shoots up and so does power.
So a rally engine would rev say 2500-7500 revs, whereas a race version of the engine would rev 4000-9000 revs. We are talking usable power.

Andy.

if you are talking about complete maps that you can interchange even with the engine running, you can do that on the marelli ecu (16vt) for 30euro (twin map adapter and chip from moates.net) or 40 or so for 8 maps (which I personally find pointless)

V.

Fair enough, but on a modified engine, the OE ecu will never be able to be optimised unlike the aftermarket ecu's. On the Omex for instance, you can have over 2000 different maps!!
Just think of it this way, you build the engine to take high boost, but you want to run most of the time at normal boost. so you have a optimum map that runs your car as standard. Yet, flick of a switch, it can run high boost, again with optimum mapping. Advantages, are better fuel consumption, additional traction control, anti lag, launch control, over boost facility, and the best bit, its interchangeable between none Coupe cars!!

Andy.

Andy, you are right I don't think anyone will argue against that, however

cost of installation together with sorting out all the various sensors that need replacing (crank, temp, map, maf, you name it...), testing and time on the RR tuning it we are talking some serious money right?
It's not 1 or 2 grand for forged rods/pistons and the paraphernalia needed. Again if you are keen on traction control and fancy stuff like that the balance moves back your way

V.

Omex can be ordered with bespoke wiring loom, so it will fit pretty easily. Its not that dear to buy,, certainly well under £2000 to buy and map, but you can use it on any car you choose. Over say 2 years, if your mileage is reasonable, it will save you quite a bit in fuel costs, as other cars with Omex, are excellent on fuel !! If needed, you could also sell your Omex and the market would dictate an easy sell too!!

Andy. \:\)

Anyone would think you're trying to plug Omex a bit?

But can it do 5 cylinder sequential firing? That's the trouble, most aftermarket ECU's cant, it's either 4 or 6 cylinder, not 5, hence why people keep the OE ECU

Hi Alexis. Yep, both the new DTA and OMEX can do sequential. We have one fitted to a Punto HGT, and its running fine. Can do 5 cylinders as well. This is the baby.
http://www.omextechnology.co.uk/Ecus/710/omem710.htm

Andy.

yes beggers I knew that , I was just pointing out that Porsche who are virtualy able to do as they wish,or as they have the means to,has not stuck all the power high up the rev range, but has made it available from VERY low revs,and have a very very fast driveable car.
and no i`m not saying it`s not fast high up the rev range too, the turbos` used allow this ,but they hve still chosen to have the max torque range between 2200-4500 revs

Post deleted due to claiming work that is untrue

Here is my question tho andy.

The supra comes with a twin turbo, but most of the high power ones are a single turbo. So obviously there is a disadvantage to having 2 turbos. Is this a move in the right direction?

Ross

Supra have small twin turbos blowing sequentially. I want to blow a small one into a big one, there generating fast spool up and increased density. It will also take up less space.
Or maybe a Supercharger blowing from idle to 4500revs, and Turbo from 4500-8000+ revs.
The electronics are out there as shown by VW, but sticking a Supercharger on has its space problems. Possibly space to put it is where the Aircon pump sits.
Its all pie in the sky until we actually decide to go ahead and build a fast Coupe. My partner has Jaguaritous at the moment, so its all jags being done.
Plans are to have a race XJS next year, and it may appear at TOTB if finished in time.

Andy.

Post deleted

O/T

But since you posted it, 2 large turbo's (but smaller than 1 larger one) will still produce the same power as the single large one. Just more expensive to do as you need 2 of everything.

Post deleted due to claiming work that is untrue

Post deleted due to claiming work that is untrue

sounds very similar to my engine spec.........apart from the turbo,very nice

my oppinion on this thread is although fuel has missed a few points i think what he is trying to say is why does it matter if the power is up the rev range, you are either pushing it or your not, so if your not you drive of boost and if you are you drive on boost and poviding that boost is there once you change gear it does matter what turbo it is. however on the flip side paul is trying to say he doesnt want 2shift down from 5/6 on the motorway when he needs to over take as john s has said its about flexablity.

all i can say (others have said it) paul is try and get out there and drive a few (i am sure owners local to you wont mind) i personnally run a gt28rs with the 0.86 housing, i have been driven cars with gt28r,superspools,gtir,gt28rs 0.64, gt2871r and i find the gt28rs with the 0.86 housing offers me the balance I FEEL suits me.

i would say that there is very little difference between the 0.64 and 0.86 (can not comment side by side but at least from a driving point of view) gt28rs's and because there was very little i decided to say stuff it i want a few more ponies

i think the gt28r/gt28rsr's are probably slightly more flexible but i personnally dont think the difference wants losing out in the power stakes. I will say though in my oppinion the gt2871 just pushs the power a little too far up the rev range for me but again its all about YOU and your driving style, but i dont regret the gt28rs 0.86 one bit

if that helps (probably not

He Paul ! of course it helps ,good to hear as many opinions as poss,thats what this thread is all about
So your opinion counts as much as anybody else,especially as you have tried a few turbos already

Paulr20vt - what power u got from your setup?

Ross

ESSAY ALERT!!!

@Paul... glad it helps. (more below)

@h2yper... I wish I knew, I have had the car off the road for around a year, just playing and testing with different setups, I am not going for all out power as I also what something that’s driveable aswell as being a bit of an animal, I had a spell of a week or so with it on the road and it feels very strong, but have no power figure + I think bhp is just for bar talk and drag strips, not on the road, obviously its nice to have more (I am aiming for at least 350bhp) but I feel the real word differences are minimal.

The problem with the roller bearing turbo is not really lag (the turbos we are talking about are still babies in the turbo game) but their delivery, granted there is lag but I believe it more the way it feels... my examples.

I have a passat tdi sport which has a tiny 130bhp (obviously more torque), now this 'feels' quite quick because of how flexible modern day diesels are BUT more to do with small turbos imo as diesels don’t have the revs for larger turbos. Obviously they inherently have more torque then petrols but the sensation of speed is still there even with 130bhp (to be fair I think mines been remapped, but the principle is still the same).

As a standard car we are use to the punchy asthmatic small t28, which means we are used to mid range poke and a heavily tailed of top end, when we replace this with a rollerbearing turbo we totally change the characteristic of the car into a more naturally aspirated delivery, but our mind and body are still expecting that mid range grunt, so we feel disappointed, even though the midrange is still bloody shifting and would still probably kill a t28 or t28hybid!!! The rollerbearing turbos are so smooth that it irons out delivery and makes us feel as if we are going slowly when really we just killed a Porsche carrera.

In my opinion, if you could lift someone up who has never driven a coupe and put them in on with a gt28rs or similar I don’t think they would get out and say “shame the power is all top end”, I think they would get out and say “f me that’s fast and so linear”.

This might sound like I am siding with fuel, I am in part but do think he has taken it to the extreme, I don’t think you would ever notice a massive change in lag from gt28r to gt28rs 0.64/0.86.

I would finally add (don’t worry the essay is nearly over )that I prefer the drivability of the larger gt28s over standard turbos, before I would pull out of a junction and even if I didn’t want to that turbo would sometimes kick in when I didn’t need if, where as with the rollerbearing its pull out smoothly like a decent v8 (kind of )

As I said make a plea with owners to test pilot there cars

Fair play to you. At least it sounds like you have thought it through.

However, i dont feel that compremise has to be made. Im hopefully gonna get some proper graphs this week to show good spool up and peak power. Yes, i drop a gear when i wanna race someone but having that low down grunt is very useful around town.

I never find the turbo comming in, as the off boost performance (below 2500rpm) is very strong and torquey.

Ross

you're going to have it mapped?

or you simply go for a RR run to see how it fares?

V.

Something like that

Ross

very informative post and well put thanks Paul,gotta agree with a lot you have written.

In that case hand over the RSR

Ross

still toying with having both rsr and rs and trying them both out.

h2ypr-just noticed you have almost 8000 posts jeez,do you carry your pc around with you

Nah just talk a load a sh*te.

Ross

p.s im actually at work just now. Sunday's are dead.

i must say i havent driven an rsr but expect it to be between the gt28r and rs (obviously) if you have the rsr there and in your hands then maybe you should stick with what you have.

drive some

I doubt there's tat much difference between the RS and RSR? The money you would spend on an RS could go towards all sorts of things, like a S3 head!

He has a stage 3/4 head i believe!!

I would run with the RSR.

Ross

DTA, OMEX, MoTec, Pectel, Autronics, you name it cannot reduce the lag down appreciably unless you are using antilag - the std ECU is just as capable at mapping to support good spoolup as any aftermarket ECU - that means doing stuff like throttle enrichment and throttle movement based advance adjustment. The only way you can reduce the lag is engine work be it higher compression, better head flow, advanced inlet cam or whatever external breathing like variable inlet length etc.

Std sump is baffled pretty well - lessons learnt from the 16VT engine, not sure unless you can properly model it that you can do much better more likely to do more harm than good to be honest. Only effective way to improve it would be either something like accusump or dry sumping

http://www.fiatcoupeclub.org/forum/ubbthreads.php?ubb=showflat&Number=464710&gonew=1#UNREAD

have a look here paul, there is a ultraspool (which i believe is close to the rsr) v rs map of power and torque, might give you some ideas

Paul

the solution must be always SPOOL UP and LESS POWER......




















http://upload.spyro.it/public/8549/Foto%28625%29.jpg

I have no experience of any turbos other than T28 and Hybrid T28s, but I think this one knocks it right on the head.

One of the best features of the 20vT is the low-down torque. After driving pretty much anything else (even 355s or M3s) most owners comment on how 'peaky' the power delivery of these cars is. We get back in the coop and love the low-down grunt. Any owner going from a T28 to a GTxx is going to worry about losing that wallop of torque well below 3,000rpm. If the coop had never had this, you simply wouldn't miss it.



I'm actually really suffering from this off roundabouts lately. Just yesterday I pulled out onto a roundabout pretty quickly behind another car to get into a smallish gap. The car infront slowed suddenly and just before I let of the throttle, boost arrived quite savagely, then went just a quickly. Everyone in the car was thrown all over the place by a 4mm of travel from my right foot. It really is sooo annoying, worse than ever after the FMIC & SI.

I have in my hands a nice new RSR,but i think maybe the RS will be the turbo of choice

Going onto one of the bigger Turbo`s (ie GT2871R ) will, for me anyway, push the power up to high.

So what difference do you reckon between RSR-RS.............I`m guessing, 20-25 bhp more and(with my mods)maybe only 200-300 higher for spool up ?

If you can be bothered (more just for the fun of it ) what do you reckon on power output for my engine with rs/rsr( chargecooler will be removed)......probably go for around 1.6-1.8 midrange tailing off to 1.2 redline

Looking at 007s results in the RR section, an RS will have probably caught up with an RSR by 3,500 rpm, but the delivery is a little more savage (i.e. on/off). Not sure about the top end, maybe 20 BHP, maybe not. Personally, I wouldn't bother swapping if you've got the RSR already.

What Turbo would you recommend then Trappy? I love quick spoolup.

I'd recommend any turbo that doesn't do this. My T28 GTiR spools up to max boost of 17psi at 2,600rpm. I has a real on/off characteristic though and can spoil normal driving when it comes on suddenly just before changing up. I like the sound of these GT28r/rs/rsr jobs with the more progressing spool-up and bigger top end, and considering the money these now go for, I'd go for one of them if my current turbo went again.

When you getting your rolling road dude?

Ross

I don't think it's worth moving from an RSR to an RS. I think the RSR is better in most respects having driven both. The RSR loses a lot of the off/on-ness of the GT28RS. The power difference is relatively small at the top end but has a decent improvement in spool. Marcus' car made 380BHP with an RSR and Barbz' made 392BHP (I think it was) with a GT28RS so for 10BHP I would take the better spool up every day of the week as well as the better behaviour (less off/on)

JohnS : Thought marcus made 370?

Ross

It was 378. Also, I'd definitely agree with the on/off comment above, I find the RSR a little on/off as it is, looking at recent RR results the RS seems to be alot worse in this respect.

Me? I'm going to the Surrey RR day on the 10th

having not driven an rsr i would take john s's advice, as i said previously i dont think i would not use an rsr in favour of an rs if i had already bought an rsr, but would probably get the rs over the rsr if i was buying new again

I'm heading for the GT28R (god send me the money please!).
What's the max power anyone measured with this turbo? And what was the mods?

Swapsies?

On a standard engine you'll make around 300 bhp. With headwork, cams, and decent mapping, with 3 inch exhaust, fmic, etc. 350 is possible. An RS with a 0.64 housing does not spool much later and is a lot more easy to extract the power from....

I'm putting together an excel spreadsheet that will show the following characteristics of the different turbos available to the coop 20vT. The list is the one supplied by Johns a while back listed in order of spool-up.

The turbos featured are as follows;
T28 Superspool hybrid
T28 Std turbo
T28 hybrid
T28 GTiR hybrid
GT28 0.64
GT28R 0.64
GT28RS/R hybrid 0.64
GT2860RS 0.64
GT28RS/R hybrid 0.86
GT28/32 hybrid 0.64
GT30/25 hybrid 0.64
GT2860RS 0.86
GT2871R 0.64
GT3071R 0.64
GT2871R 0.86
GT3076R 0.64
GT3071R 0.86
GT3076R 0.86
GT30/35 hybrid 0.86

Where does the new(er) 'Ultraspool' fit in?

Johns also supplied the max power made on each of these turbo (at the time). I 'think' it was irrespective of headwork and so maybe corrupt for purely comparative purposes. Maybe the best way to do it would be to collect data for cars that don't have any headwork first (also only 2.0 engines), then collect those that do and see if what difference they make. I tend to think the bigger turbos would benefit more from headwork, but it may simply be a % increase in power/torque and a fixed reduction in spool-up rpm? Of course the 2.4/2.5 jobs are another factor to be considered.

I intend to add these other 'attributes' along the top of the database:
Max Power rpm
Max Torque
Max Torque rpm
Boost Threshold rpm (spool up rpm)
Boost Trails off rpm
Torque Range
Redline Boost

A new thread would probably be the best place to put this info so could anyone with any of those 'attributes' above please post them up on a new thread along with a 'rough' list of engines mods.

Something like this could answer a lot of recent questions about which turbo to chose.

Cheers

I've just remembered Johns' post about different spool rpm in different gears. Go by 4th gear as most people will have used this on dyno runs that show boost on the graph. Of course everyone else could just use 4th gear on the road.