cannot make over 10 psi of boost

[ohcbird]

"Hits a wall at 10psi"

Since you've eliminated all the other variables, I'd check the exhaust pressure going into your hot sides. If you're seeing over 20 PSI there (2:1), then you've found a restriction. The closer to a 1:1 ratio, the better. As a side note- do you have any EGT probes? I'm curious as to what your gas temps are hitting. Do you notice a more-than-normal rise in IAT when you're on the boost for a while?

I agree that your .81 housings are about right & should work fine, but you might be right at their limits already. I think that motor is trying to move alot more air than it currently can, hence the 'wall' effect. I think you can get 1.01 housings for those; that might be worth a try.

[deuce_454]

Originally Posted by ohcbird

"Hits a wall at 10psi"

Since you've eliminated all the other variables, I'd check the exhaust pressure going into your hot sides. If you're seeing over 20 PSI there (2:1), then you've found a restriction. The closer to a 1:1 ratio, the better. As a side note- do you have any EGT probes? I'm curious as to what your gas temps are hitting. Do you notice a more-than-normal rise in IAT when you're on the boost for a while?

I agree that your .81 housings are about right & should work fine, but you might be right at their limits already. I think that motor is trying to move alot more air than it currently can, hence the 'wall' effect. I think you can get 1.01 housings for those; that might be worth a try.

my thought exactly.. but check the boost before at the turbines just to be sure....

you could have another issue causing it.. some manual boost controllers need to be plumbed to both sides of the diagphram on the wastegates.. so they hold them closed by applying pressure on top to hold the valve closed till the boost hits preset, and then they release this pressure to allow the valve to open.... just make sure you havent got the hoses crossed (mounted wrong) on one or both sides so your boost controller is actually opening the valve instead of keeping it closed

[awr68]

Jody, sorry to hear that you are still having troubles....but we know you will figure it out.

And since you started this thread we all can learn from it!

[camcojb]

well, some progress made. I hooked a separate boost gauge to one of the turbo outlet housings and took a drive. That shows 15-16 psi at the turbo, before the intercooler, and the in-dash gauge and map sensor both show 10 psi at the intake plenum.

So there appears to be a big restriction in the intake system, or a huge boost leak. I think the intercooler is fine as it was on the car before without issue, but it's a definite possibility it's restricted or plugged somehow. Possibly the big 90 degree angle coming right off one of the turbos (required to clear) is affecting it, but I've had right angles on the pressure side before. Maybe the boost is pushing past the o-rings on the sheetmetal intake.

I need to get a longer piece of hose and hook the gauge to the other turbo and see if it's different. The intercooler will be a pain to remove, most of the front end stuff has to come off (grille, bumper, etc.).

[ohcbird]

Well that's a relief. PT usually doesn't get much wrong IRT turbo application.

Good luck on the rest of the troubleshooting...

[projectile]

Jody, I have some 90 degree bends on the pressure side of mine also! I don't remember what my pressure drop was from the turbo the the intake. I checked it about four years ago but just can't remember now. I've run boost as high as 18 psi and didn't see any high spikes in intake air temps or other issues. If you want, I can hook up a guage to the turbo tomorrow and take a reading. At least you can compare my results to yours before you go through the trouble of taking the front end off of your car. I know that your pressure drop is excessive, but maybe some real world numbers might help...

[camcojb]

Originally Posted by projectile

Jody, I have some 90 degree bends on the pressure side of mine also! I don't remember what my pressure drop was from the turbo the the intake. I checked it about four years ago but just can't remember now. I've run boost as high as 18 psi and didn't see any high spikes in intake air temps or other issues. If you want, I can hook up a guage to the turbo tomorrow and take a reading. At least you can compare my results to yours before you go through the trouble of taking the front end off of your car. I know that your pressure drop is excessive, but maybe some real world numbers might help...

I appreciate that Ray, but hate to have you go to the trouble. My next step is to make a 3.5" bypass for the intercooler and see what happens.

Jody