L1*WRX

hi all am quite new here but thought id post my problem up as im scratching my head at the moment. i run a subaru impreza sport with full version 4/5 sti running gear and engine wich pulls and drives loveley its had an uprated vf35 turbo, fmic, hks dump valve, blitz induction kit ect ect but heres my problem if i try to run over 9psi it just hits boost cut only ever in 4th and 5th. i thought it was because the fuelling wouldnt be up to running much more but had it put on the rollers and the fuelling was more than enough especially at the bottom end but still loads at the top. the car ran 300bhp exactly wich is very good but at just 9psi its only 1psi over standard.

theres my problem guys any ideas?

cheers

FB Tuning

iTrader: (30)

Are you sure your boost gauge is accurate?

As far as i can remember, fuel cut on a standard STi5 is at around 17psi

davers

obviously yours is tuned but, im having a boost cut issue too, like hitting a brick wall??

see https://www.scoobynet.com/general-te...rick-wall.html

L1*WRX

yeah but ures sounded like it was hitting it almost as soon as boost comes on? correct me if im wrong!lol where as you will see mine go over 1 bar and as soon at it does it cuts!

well as far as the guage being out that was one of my 1st thoughts but even the rollers said that in 3rd it ran 9psi each time so thought it couldnt be!

yeah ive heard the same that they can run 16/17ish

dan83590

Second that. It's certainly way above 9psi.

It should be 1.1bar, that is 15.9 psi. Are you reading your gauge correctly? Example - Are you reading 0.9 bar as 9 psi? You wouldn't be the first or the last.

FB Tuning

iTrader: (30)

...Also, i'd be surprised if a VF35 was making 300hp @ 9psi.

Have you got dyno plots to post up ?

L1*WRX

heres the graph, thats what my mate said at motorworx that dyno'd the car but he said it must be quite healthy he was suprised as was i at such low boost presures


let us know if this helps the dylema lol

L1*WRX

hmm sounds stupid but maybe i am reading it wrong, but then the dyno said it was running 9psi im sure of it??

tomdscooby

have u got any other graphs? like the boost curve, the air/fuel mix across the revs etc, might help

tomdscooby

and the bhp might be 300, but 260 odd ft/lbs of torque on that turbo seems quite low.. boost leak maybe?through a split pipe or your dump valve? try a recirc dump valve,easy swap before u search your pipes etc

also, strange that your torque dips slightly at 3200 revs? and are you sure he didnt say 0.9 bar? which a uk turbo runs on(not sure on a classic sti?)

L1*WRX

yeah i thought the same with the torque and you really feel it on the road aswell, what would 0.9bar equate to in psi then?

FB Tuning

iTrader: (30)

0.9 Bar is about 13.5 psi

L1*WRX

so even if it was running 0.9 bar it should still be able to run more? im sure it was psi tho