I edited as approriate...

oh my bad.. engine mods gotcha

new dyno numbers with TGV deletes
 

well after waiting a week here are my new dyno numbers with my TGV valves deleted. had a ported throttle body installed, but they had to go back to a stock one because it was flapping after letting off after WOT. pretty good increase for such a small mod. got +8hp and +15wtq. up to 280hp and 247tq(@17.5psi). also got a race gas map tuned for about 96 octane. ran 290hp and 258tq....only 10 hp and tq gain on race, but i think at 19.5psi my vf 34 is about out of air. no real difference in turbo spool up but the increases all around were very pleasing. car drives awesome and the power is very good. anyway thats the update and the attached overlays of my charts.

ryan

btw, mike W. told me that with 280hp my wrx is the highest they've dynoed with a vf 34...so im pretty happy about that. not bad for the pretty crappy usdm wrx block.

Mods: Cobb TBE + GT Spec headers + pro-tune
Wheel HP: 268.0 @ 5250 RPM
Wheel Torque: 303.0 @ 3750 RPM
Dyno: Mustang @ Gruppe-s 12-Nov-05

Hey Mike, I don't have any previous numbers for your STI. Got any baseline, or anything?

Those are real close to my numbers :huh:
I think Iwas at 268 and 299 :eek:
Mike are you catless?

Page 5 of this thread!

No, I have a cat

Hey Mike, who tuned your car at Gruppe-S and do you have a graph? You've got some sick torque for your setup.

Also, is it true that you always have to port the WG when you free up the exhaust on an STI?

Those were also really close to mine with similar mods. If I remember mine were also with the injen intake. I think mine was 269 and 310 (hiccup). I had no cats though. I'm starting to think the cats only take a couple horses at this point. What PSI are you running?

It was tuned by Mike Warfield at Gruppe-s on their indoor road dyno (username GST_Mike on this board) . Chart is below. I have a cat and custom tuning so I have never had a problem with boost creep.

I think 18 tapering to 13, or something like that.

When I was at cobb Trey told me that their cat cost around 5 Hp.

That's cool that you didn't have to have the WG ported. Congrats!

When I had my VF39, I didn't either and I was catless. I never had boost creep.

Cool. Why do some STI's "have to" have it ported?

non-ported wastegates can cause the boost creep issues on free-flowing exhausts. So, two ways to fix the problem. 1) Port the wastegate. 2) Tune around the boost creep.

Simply put, porting the wastegate is the physical fix, and tuning is the software fix.

And on some cars... the software fix isn't enough and they creep anyway. But up at this altitude, it doesn't seem to be a problem... I can't think of any tuned cars that are creeping up here.

Sorry to say this but there is no way to safely tune around boost creep, even if you set the wastegate duty cycles to 0 from say 4200rpm a car with boost creep will still creep under load say getting on it up the grapevine or something like that in 5th or 6th.

If you have boost creep simply smooth the leading edge from the uppipe into the WG port and you'll be cured.

Mike

Interesting...are there specific UP's that are more likely to cure the boost creep issue before it starts? It just seems like if the WG is too small to let enough exhaust pressure out, you're going to get creep...no matter what.

Typically cars with very good flowing exhausts are more likely to exhibit it, we saw this mostly on the original P17 housing, If recall all the vf39's now ship with P18 housings (I could be mistaken here) which fair much better.

If you have a turbo in your hand I would port the thing anyway, it's not very difficult to do and for the little time and effort can lead to better spool up as well as protect against the possibility of creep.

Mike

Good info Mike...thanks.

boost creep is over rated :lol:

fuel cut is what teh sucks :P (can be tuned out)

Yeah, I meant to imply that porting is the real solution, and tuning is only a bandaid.

But, for a lot of people, tuning seems to work most of the time. Tuning may not completely eliminate the issue, but it does lessen it. As you said later, I would also suggest porting the wastegate if you are already holding the turbo in your hand. No reason not to do it at that point.

Here's some car I found on the dyno today.

Awesome. Congrats Scott!