I'm all tingally ......
Thread Starter
Melting Slicks
Joined: Jan 2002
Posts: 3,293
Likes: 79
From: Jackson MI
Originally Posted by dgoodhue
If you only have 15hp/15ft lbs of torque from an additional 5psi your ECM is most likely taking all kind of timing from detonation. What does your Intake/Manifold air temps look like.
Melting Slicks
Joined: Mar 2001
Posts: 2,150
Likes: 304
From: Timra, Sweden
You probably measure boost in the plenum.
The wastegate is probably sensing boost directly after the turbo.
In that case the 'boost loss' as the engine rpm increases is probably from restriction in the ducting and intercooler.
That drop is only a few psi and it does not explain the power loss.
At 6000 rpm the engine should make way more power with 13 psi boost than with 8 psi boost.
I think your problem is too much exhaust pressure and you need a bigger turbine housing.
Can you measure exhaust pressure? Weld a feet or two of thin pipe to the exhaust before the turbo to get away from the heat, then use a boost meter.
The wastegate is probably sensing boost directly after the turbo.
In that case the 'boost loss' as the engine rpm increases is probably from restriction in the ducting and intercooler.
That drop is only a few psi and it does not explain the power loss.
At 6000 rpm the engine should make way more power with 13 psi boost than with 8 psi boost.
I think your problem is too much exhaust pressure and you need a bigger turbine housing.
Can you measure exhaust pressure? Weld a feet or two of thin pipe to the exhaust before the turbo to get away from the heat, then use a boost meter.
Thread Starter
Melting Slicks
Joined: Jan 2002
Posts: 3,293
Likes: 79
From: Jackson MI
Originally Posted by JoBy
I think your problem is too much exhaust pressure and you need a bigger turbine housing.
That's what we came up with too. Hence the q-trim turbine instead of a p-trim and going to a non-divided housing should help too. I acutally take the boost reference from the intake piping directly before the TB. I did this intentionally to get around the boost drop from the intercooler.
I've thought about hooking up a boost gauge to the exhaust setup. But even if I find out that its to much there really isn't anything I can do to fix it. I got the biggest turbine and housing(with in reason) that I could to fit in the space that the kit was designed for.
I'm definately going to stick with the 7psi setting for a while, probably a long time. I think 500+ hp will get me to where I want to be for now. And I'm really sick of blowing up my engines. I just want to drive my car.
Instructor
Joined: Dec 2005
Posts: 197
Likes: 0
From: Woodland California
Originally Posted by dgoodhue
I would guess the turbo couldn't supply enough CFM to hold peak boost at high RPM. If the wastegate was getting blown open it would have never made peak boost. The chunk of headgasket is from detonation, their is no way back pressure from a turbo exhuast housing blow off a chunk of headgasket and disformed the piston. It may have indirectly caused it through heat, but I would bet it was the detonation that did the damage.
