Engine/Transmission (1994 - 1998) Max boost for HX35-12

[Bob Wagner]

why don't you stop pulling your hair out and call and talk to Piers.



Piers has a toll free number on his website Piers site



Piers would be more than happy to answer any of your questions.



Piers&reg Turbos ROCK

 

[WadePatton]

I hate to bother those folks during business hours when I'm not ready to buy a product.



I might anyway.



Besides, I gots plenty of hair.

 

[Bob Wagner]

Piers is in the same class as Bill Kondolay



They are not looking for a quick sale, they love to help people out.



last time I spoke with Piers, keep the HX35 around 35psi max for optimal operation



40 psi is way out of the efficency map



I run a piers modified HX35 and I love it

 

[KWIKKURT]

Originally posted by Archive

Thanks Joe,



I know I need a bigger exhaust housing. I am holding off for the HX40-16 though. I was just curious as to why 40 seems to be a brick wall with the stock turbo.



Enquiring minds want to know. #ad




Thanks for the tip,

Chris

Chris, You are probably just blowing open the wastegate. With the pressure hose unhooked there is the spring pressure holding the waste gate shut. Then when the DrivePressure of the turbo gets up high enough the wastegate is pushed open by the pressure. You could add another spring or wire it shut but it is not a good idea. Once you are over 36-38psi with the Hx35 you are wasting HP. . Kurt

 

[WadePatton]

Originally posted by KWIKKURT

Once you are over 36-38psi with the Hx35 you are wasting HP. . Kurt

After first drilling it was still making a sustained 40psi. So I drilled some more and have yet to see over 38, but hain't really put a load on it.



I'm gonna open the holes one more step.



[I'm drilling out the boost elbow to reduce boost #'s--was getting over 42#]

 

[danandamy]

turbo boost

With my stock hx35 12cm I could easily hit 45# I wound up going with the PDR35 16cm and boost only hits 40# at wot now. The PDR 35 spools up much better than stock even though it has a larger exhaust housing. Egt's at the drag strip didn't drop dramatically but egt's when pulling are WAY down. As mentioned earlier, it's easy to damage the stock turbo when over boosting like this. I was makin' mine BARK LIKE A DOG on a regular basis. When I pulled it out, I could see a spot on the compressor side where the wheel had made contact several times, very very ugle.



dan

chatmoderator

 

[WadePatton]

I barked mine once driving it like a gasser. Wound it up and lifted for the turn --and EEK GAD! what was that? Must be the dreaded turbo bark.



Anyway-the good new is that after some judicious drilling of my boost elbow, I have limited the boost to 34-36#. Very happy about that.



Will probably get a 40 at the same time I drop in the DD3's (a big weekend!). Not in a rush, can't drive the dang thing straight now with wet roads.



But with my stock 35 now limited to 35 or so psi, I'm feeling better about its longevity and efficiency.