Shorla

What is the maximum boost can i run on my '96 Sti (with a standard turbo) because i heard that they have forged pistons. Im currenty running 1 bar.

SoreHead

Not sure what the maximum is but the pistons are only half the problem. The turbo you have will have an effective limit, you'll need to match the fueling, you'll need to get more air in and out etc etc. There's an over boost protection to stop you going to high so that will need to be removed. 1 bar is roughly 14.5psi. I doubt the std turbo will be much use if you go alot over that (maybe 16-17psi). You'd be better getting a bigger turbo and run the same psi. You'll get more volume of air. etc etc blah blah

Jesus. I almost sound like I know what the hell I'm talking about. I'm sure someone will tell you the tech version of all that but that's the general lay-persons (see, I know there are girls here too ) run down.

[Edited by SoreHead - 6/20/2002 4:03:17 PM]

RICH WILD

It's not as simple as what boost can you run.

You can't just whack it up or you'll be looking at a potentially huge bill.

If you are increasing your turbo's boost you are shoving more air in and hence leaning out your air/fuel mixture. As you lean it out the combustion temps rise. Do this too much and you are going to melt something.

So, in order to up the boost you must ensure you have the fuelling to match. Your car is an import so it should be mapped to run 100 RON fuel. In this country, the best you can hope for is Optimax at 98 RON, so octane booster is a good idea.

What other mods do you have. A full decat and induction mods maybe a better idea if you've not done it already, but again that will also lean out your mixture.

You need to check that your fuelling is up to the job first e.g. uprated fuel pump maybe, fuel controller or HKS AFR and then also you need somethging to monitor the mixture e.g. EGT gauge, Lambda link or ideally both. Knock Link may be a good idea too.

As for the turbo, think you will be on the TD05 if it's an STi2 (I think). If so, absolutely no need to swap this at all. I run mine to 21.5 psi (1.48 bar) with all the suitable precautions taken.

Need more info really to advise you further but DON'T just wind up the boost if you don't know what you are doing, it will probably end up leading to a rebuild.

Cheers
Rich

Katana

I'm currently running at 19 psi on an MY93 WRX. Fun eh?

Shorla

Cheers lads. Rich i have a filter with a full decat system at the moment. Im looking into getting a tec or link ecu before i do anything along with an apexi AVC-R, i just get lost with the rest of it-what internals needs to be uprated, what boost the turbo can handle e.t.c. General opinion is that fuel pump can cope within reason What has everyone else had to do to boost over 1 bar??

RICH WILD

Hi,

You shouldn't need to uprate internals yet IMHO.

I'm running a 96 UK turbo with standard internals, standard turbo, standard injectors and standard ECU, but that's where the standardness stops!

WITH EXTREME CAUTION AND A LOT OF BACKGROUND RESEARCH I run 21.5psi held and am presently knocking out 331bhp from a standard 208bhp lump without running too lean at the top end.

There are those who say this is very risky and I'd agree. If anyone reading this is tempted to follow me, note that unless done properly there is a REAL RISK of totally bolloxing your engine.

I may be very lucky or just a damn good tuner

cheers
Rich

crusher

So what's the secret recipe for that sort of gain...with so many "standard" parts?

Katana

Dawes......

UkLegacyT

running 25psi max on mine, 22 held.....flies

poorly at the moment though, so be warned