timmy2take

iTrader: (7)

I've got a STI with I think its a v3/v4 engine, even though I was told it was meant to be a 6. The car is meant to also have uprated cams (although I have no paperwork to back this up) and a 1.6mm head gasket, it also has a FMIC and has been mapped with an Apexi ECU and commander.

As you'll see from the pictures the boost tails off in the high end, do you think it could be the apexi commander not being able to handle it, 3 point boost solenoid, the standard turbo not being able to push 1.4 to the redline, or the combination of the cams, FMIC and Head Gasket (whats should the standard HG size be) Possible weak aculator?

The peak boost seems to be kicking in quite late, around 4800rpm. Would a weak aculator cause this?

Do you think the standard turbo will push 1.4bar of boost to the redline on this spec? Do you think this turbo on this spec is spooling up at the correct time?
PIC OF BOOST & BHP


PIC OF POWER & TORQUE

scoobian

I cant answer other than I dont see the Apexi as being the issue -it'll run whatever you set it to
did it run 1.4 bar consistently when you had it mapped?

nampahc01

surely the guy who did your rolling road run can tell you all you need to know or he's not a very good dyno tuner

gtirx2

He has not had the car long, so was not there when it was originaly mapped.
The rolling road operater said it was the apexi pfc not being able to control the boost very well.
It is ment to have a 3 port boost solenoid on there but we are not sure if it is a subaru item wired into the pfc or apexis own boost solenoid yet.
What sort of boost is a standard sti3 turbo surposed to be able to push?

AL99

iTrader: (1)

im not actually sure what turbo you are running from your description but to give you an idea a td05 16G @ 7000 rpm will be blowing a lot of hot air @1.2 bar. YES you can run 1.5/1.6/1.7 at 4000 rpm but after 6000 rpm you will find the boost will naturally drop.

however, you have EXTREME amounts of lag. This could be down to many things. Boost control / split vac hose / poor Apexi map / boost leak / Duff wastegate / etc..

who mapped it? can you not take it to them and ask their opinion?

Apexi AVC-R is a good boost controller with gear compensation. I use an
AVC-D ( 40 quid!) which came with a 3 port apexi solonoid and can control boost via RPM and SPEED so gives good boost response in lower gears.

as an idea, i get 1 bar @ ~3100 rpm with a td05 20G in 4th gear. 5 speed.

gtirx2

Thanks for the reply mate,i will get him to find out who mapped it.
I to was thinking its a bit laggy but as he is not 100% sure what has been done to it yet we are not to sure where to look first.
Like you said above it could be a number of things boost leak,weak actulator etc as if it is the stock turbo it should spooling up a bit sooner.
The other thing i was wondering is if the cams would cause it to come in a bit late.
Also he is not 100% sure on the spec just yet and i think the last owner said it has 1.6mm headgaskets and posserbly aftermarket forged pistons,i wonder if it has been built as a lower compression engine to take more boost as that would help explain the later spool,plus the front mount proberly dont help.
What thickness are the stock headgaskets on an sti?
I am not sure if it has a problem or not as when it does come on boost it does pull very well indeed and i think it made good power for the boost it running.
Maybe he wants to be looking at getting a bigger blower instead of a boost controller as if it is the stock turbo i dont think it will push the boost he wants happerly anyhow.

STIAN

Standard Turbo will be a IHI VF23, at 1.4 bar you are at the limits of the Turbo but with a boost controller it will hold it. A lot of mappers intentionaly have a drop of of boost at higher RPM for safety. Stock boost control by the look of it IMHO is the issue. If the actuator was at fault you would see a lot of fluctation around peak boost.

Your Lag will be down to yor front nount as you will possibly see up to 0.25 bar drop from the solenoid to the manifold.

Stock head gaskets are 0.7mm i think so running 1.6mm you will be lowering your compression allowing you to run a higher boost.

Jolly Green Monster

iTrader: (4)

Huge lag issue.. either fmic leak, exhaust leak, or actuator had it..

Recent Sti3 on tmic and 3port and powerFC controllnig the boost I got 340bhp from also on same make dyno as that.. but the torque was 330lb if I remember correct.. the spool was entirely different to that..
My money would be on actuator weak or header leak as it is making the power at the top end.

Simon