Just out of curiosity, how much boost can the stock STI turbo run?

 

15 psi no 35 psi.

 

15 PSI? thats it? how is that so? a stock WRX will run 16 all day?

 

i dont think it's 15 psi ...

 

It is a 2.5 Litre engine with performance components. You dont need a ton of boost to achive 300hp

My 1965 lotus elan has a straight 4 and is puting out 294hp none asperated. runing dual webber's so I would hope a newer technology engine with fuel injection can achive 300hp without 900lbs of boost.

my 2 pennies

 

Not even close. A stock WRX (not STI) will top out at 14 and will be there for about 2 seconds and then drop to 13; furthermore boost in 1, 2, and 3rd gear is ECU capped at 12psi.

 

I hear ya on that but I dont really care what power the STI makes with that turbo> I am jsut curious as to the actual flow limitations of the STOCK VF39

 

dude I dont konw what your talking about but...before i even had the mods, with a greddy boost gauge to monitor it. I was making 14 psi in all gears and almost 14 in 1st. I dont know, I have heard of all different cars making different boost. But right now I am running 16 with my mods and it was holding with little drop twards redline. now wiwth the header and uppipe the boost falls off a little before redline, but its fast all around. Just wondering if ANY ONE knows how much boost people are running on VF39s.

 

I was running 17.5 psi on my vf39 for about 8 months with no issues.

 

Pay attention. You are posting in the WRX thread, not the STI thread. I was discussing the WRX stock turbo, not the STI stock turbo. Perhaps you'd get better results if you had thought to post to the correct forum.

 

look dude, Im not trying to start a flame war here. I shouldnt have to post this in an STI forrum. Maybe results would have been a little quicker if I did. People ask all the time about different turbos, thats what this is isnt it? A different turbo. I dont care what kind of power it makes on an STI. And if I recall, I dont remember asking about a stock WRX turbo, though I appreciate the extra info. Anyhow, there are plenty of people running this among many other turbos on WRX's wich is why I posted here. Just my 2 cents. Thanks for the concern though. Next time I will try to post in the "correct forum"

 

Sorry, I didn't mean to jump on you -- I'm just not certain exactly what you are asking. Do you want to know how much boost you can run in the stock STI turbo (VF34/39) when it is installed in a WRX? If that's the case, the answer is easy -- there is a fuel cut at 19psi, and in stock trim in the STI the turbo runs 15.5psi (1 bar). I've heard of attempts to run over 19psi with a VF34, but that requires a ton of supporting mods (fuel rail, injectors, fuel pump, ported wastegate, ECU tuning) and would probably be a short run before a rebuild. I think the EJ20 block can only supply enough fuel for 16psi; anything over that without fuel supply mods would cause some dangerously lean conditions and detonation.

There is also have an "aftermarket turbo" forum which is where most of the turbo-swap related discussions happen.

 

the turbo will house 350 horses. The amount of boost you're willing to go is up to you. I'd be more concerned about how much your block can house.