my rolling road results !

coupe 20v turbo.
standard internals mods.
turbo gt28r.
gtech 2 chip.
apexi boostcontroller.
hks airfilter.
big intercooler.
walbro fuelpump.
3.8 fpr.
supersprint exhaust no cat .
results: 302hp 415nm 1.3 bar boost.
:).
greetz kevin.

Good results, I'll be going on the RR in a few weeks with an almost identical spec:

GT28R
standard internals
gtech 2
apexi AVCR
K&N cone
SIP
Pro Alloy FMIC
Blueflame turbo back decat exhaust
Walbro 255 + wire mod

Should hopefully be about the same


Is a 3.8 FPR necessary?

havent got one of those, does yours run lean without do you know?

perfect example of how to get 300bhp safely - all the correct modifications and a safe level of boost

the only extra mod I can think of is the direct wiring to the fuel pump (prevents voltage drops at higher revs)

I'm also slightl;y surprised that you needed the 3.8bar FPR - most Coupes will give over 300bhp on the standard injectors with the 3.0bar FPR

I have direct wiring to the fuel pump + sip
greetz kevin .

Wiring to the SIP, what's that for?

have another read matt

good results by the way!

I knew that...

thats the problem with the white stylesheet, you can't see smilies! doh!

1.4 bar good safe level of boost ?

The turbo will run that, but any more and it wont be efficient - the issue is the fuelling and advance with 1.4 bar.....it will be fine if the map is spot on, but otherwise you are pushing it on the standard internals IMO.

You may also only notice a small increase in bhp with more boost - there is simply a point where no matter what you do with the boost you wont get anymore (or you'll get 1 bhp for another 0.1 bar of boost) - at this point you want to back the boost down and have a car which is running efficiently.

My car runs the same turbo as yours with a few other mods to help the engine flow and I called it quits at 1.35 bar.

You mention a supersprint exhuast...if that is mid section and back box then you will gain a fair bit from a 3 inch downpipe with a 5 stud arrangement for the turbo, and the gains will be made without having to ram more boost through the engine.

What to do next for 350 hp ?.

could go to see flea?!?

im sure he can improve on your spec!

good spec by the way!

You will have to go bigger on the turbo - GT28rs 0.86 on your spec, or a GT2871R 0.64.

You'll also need an organic / paddle clutch, and at the very least a 3 inch downpipe.

With a 3.8 bar regulator and standard injectors you are stretching the fueling system to the absolute limit.

In my opinion you MUST get the car mapped properly at this level of power if you want the engine to last. Changing to forged pistons will give you scope to run more boost - say 1.5-1.6 bar+, but you also have to be careful with the standard rods and rod bolts which can give or bend with over 330lbs/ft (from memory I think this is the recognized threshold.)

I have the same mods like you guys'and I like to ask-is that bhp at the wheels?
Mine gave 240 bhp{wheels} on 33 dg heat today

Both those figures will be at the fly...

I'm planning on getting mine RR'D after the 2nd cam belt change & once i've fitted my stainless manifold.
I've got almost the same mods as MattW & Kevin20turbo but i have a 3" Downpipe.
What sort of difference should i hopefully be seeing over their set-ups ?

Hello, which one is better for my mods ?.
1:Water / Methanol Injection Kit
2:Chargecooler kit .
greetz kevin.

You say you have a big intercooler, do you have charge temperature issues?

Just wonder why you would be thinking of a charge cooler and/or WI.

Personally not a fan of WI (yes you can get get good results with it) but you fail safe modes etc. IMO i think its a mask. maybe at BIG power you would consider it but at 300-350 i wouldnt. Its another thing to go wrong.

(All my opinion)

cheers Steve

Neither - if you have a decent front mounted Intercooler. At just over 300bhp you are on the limit of a GT28R unless you have headwork. So if you want to get more power then you'll need to go bigger on the turbo.

I'd have thought you could push the GT28R a bit further with a bigger bored downpipe/ exhaust system. On a bigger turbo than the 28R, you'd NEED a bigger downpipe to get much more power. My peak went from 292bhp to 312bhp with a straight swap (and remap) from GTiR to GT28RS.

I'd advise anyone attempting to push any non standard turbo to near it's limit to go for a bigger downpipe. I say this because both the hybrid and the GT on my car made the same power from 4krpm to 6,200rpm. In my thinking, this means that the standard exhaust bore simply can't flow any more.

yes - absolutely, but a GT28R is at it's limit a shade over 300bhp on the standard head. It just can't flow any more - even with headwork 340bhp is the absolute max.

having a 4 inch pipe wont get round the flow of the turbo and the head.

With an H&S downpipe, race cat or decat and blueflame cat back plus water/methanol injection it is possible to reach 325bhp at 1.4 bar (and 340 at 1.7 if you dare) on a standard head with GT28R (based on my results and those of jamie3 from our recent flea live maps)

Yep - 320 is about the max (a bit over 300).

1.7 bar on a GT28R is more than it should handle - it'll be puffing a lot of hot air, and certainly wont hold that at the redline.

nice what is 1.5 bar in psi?

22 psi is 1.5 bar.

I'm not sure about this, I have 275.2whp at 1.14bar - which is around 320hp on the flywheel. With 1.3bar it's a different beast, I'd say there's another 15hp there.
This could be down to many tweaks but I do think my 3" downpipe helps.

I'd put money on that extra power feeling coming from more mid range torque rather than top end power.

Yes, I'd say there's a really even powersurge from 5000 to 6700rpm. Will do a RR-session in 5th gear this spring for a correct boost/reading.

I just re-read this. Having a 3 inch downpipe will definately help. My original post was concerning how much benefit you would get going to a 4 inch pipe. I dont think you would get much more than on a three inch with a GT28R.

Garrett rate the turbo to flow 320 bhp max - I would suspect that anyone running significantly more than this on the turbo would been down to an artificially high or manipulated rolling road reading.

Well that's one way of looking at it.
(or the turbo is a little tweaked )

Also worth noting that garrett rate the turbo to 320 assuming it has a T3 or T4 housing. The T25 which most of us use is slightly smaller meaning it flows less air, and gives a bit less bhp

Also different cars have different losses due to a wide range of causes - tirepressure, tracking, camber, gearbox oil etc.

This coupé is for sale now.

I'm sure you ran 344bhp for a while Suba?

I find this max power rating thing intruiging. What happens if you fit it to a car that's running more power than this already?

Yep - I did. That's the max that has been recorded on a GT28R - Sheiks made the same figure on the same turbo as well.

My car had balanced internals, and a flowed head though - I mentioned earlier in this thread that 320 would be the max for a standard head. My car would actually dyno between 315-340 most of the time. 344 was the highest it got on the rollers - it felt the same on the road, so it was just down to the rolling road readings.

I agree the max power rating is intriguing - i'd like to know more about how it works as well. From all I know it does seem to be pretty true regardless of engine size the peak power is all to do with the amount of air that the turbo can flow. A bigger engine just means better response and less lag.

Mine hasn't really been recorded yet with Fleas latest boostmap.. then again it's not a std GT28R.