Thanks Ian & Scott,

You are both absolutely right and I'm aware of the facts you stated about turbo-lag and down-pipe.
It is indeed common knowledge that the turbo-lag as well as the power increases with the size of the turbo.
For that reason the standard turbo fitted on a MY98 onwards is a smaller version than on previous MY's. So it spins at a lower rpm. So it provides the benefit for the engine to pick up more easily with the disadvantage of a restiction in power in higher revs. Therefore the maximum bhp is reached far below the 'danger zone' of the revs.
Of course this is a compromise, for which Subaru made a choice.

What I am looking for is a turbo that spins much more easier and therefore at a much lower rpm. This should be reached with another type of bearings (don't know which type is required).
When the turbo spins more easier the turbo could also be bigger to eliminate the disadvantage in the higher revs. Again a compomise, but with a much better performance.

What I've heard of is that the STi versions of the Impreza are fitted with a turbo with the above mentioned advantages.

Maybe this will clarify my intentions a bit more. Don't know what costs I will encounter, whenever this will lead to something.

 

Hi,

Does anyone of you guys have any experience with a STI (or similar) turbo fitted on a MY99 engine?
I think the spinning of the standard turbo can be much improved, so I'm considering fitting a (larger) STi-turbo. What I'm aiming at is the smallest ever (or if possible no) turbo-lag with a power increase above 5500 rpm.
Is it necessary to change the ECU also or can I do without?

Cor (from Holland)


[This message has been edited by Corrr (edited 12-05-2000).]

 

Errr, as i understand it, larger turbo means more lag, more momentum to spin up etc ? thats why the UK spec cars have the small turbo to reduce lag.

A downpipe change will help, there are people out there with bigger turbos, but thats to flow more power, not to reduce lag.

 

Corrr

Impossible to fit a bigger turbo and reduce lag.

As Ian has said it will increase, I have the largest Turbo that Subaru fitted to a car (apparently) my turbo spins up @ 3500 rpm that is with a downpipe.

UK turbos with downpipes will spin up circa 2500 rpm.

 

Corr

If you are looking at a turbo upgrade I'd speak to a tuning specialist for his opinion, it may well be that you could get a better alternative to the STi turbo maybe a garrett or something.

Happy tuning

SJD

 

I think what corr is really after is the upgraded bearing type turbo's.......You will all correct me if i'm wrong but i THINK sti do an upgrade kit.........

m.

 

Hi Corr,

You might want to call Subaru Vilvoorde (Dirk Lauwers on +32 2 254 75 60). They did some experiments with the Impreza of Bert "Lengin" (?) a Belgian Porsche Cup pilot and might be able to share their findings.

Cheers

Peter (evo on Dutch BBS club member)