Blowoff valves prevent backspin, not boost... a 'wastegate' is what limits boost.

 

Wastegate is mounted on the exhuast between the exhaust manifold and the turbo. Bleeding off exhaust pressure to slow down the turbo. There is no need or place to put a wastegate on a supercharged car.

Blowoff valve is mounted between the blower / turbo and the intake to limit boost pressure.

Kevin's was stuck open - so bascially like cutting a 2" hole in his intake. All of the boost was blowing out into the atmosphere. Or, until the amount of boost overcame the BOV opening, he saw a little bit of boost in the engine, but not much.

 

What Hacker said-exactly.

 

Hi Jim/kevin
OK, good the problem is solved. I seem to remember I suggested BOV in another thread Kevin ?

Is your a Stage 1 or 2 kit ?

 

My apologies... my experience is from turbocharged cars, not supercharged one's... I should have read better.

 

John, It is a stage 1 but soon to be IC'D. You did suggest a bov, but we checked it to the best of our ability, but did not know enough about them. A local boost guru figured it out and helped me fab a bung for a new one which turned out to be bad. He just helped me do a Greddy set-up and it works well.

 

I had the same problem during the SC shake down testing. The bypass valve came off the boost tube and there was only ~2psi at full boost. If you are venting the BOV/BPV into the atmos. you can hear the whistle, if the air is recirculated, you won't hear this.

The SC kit that was for a '93 LT1 Trans Am (Paxton) never had a BOV/BPV or even an IC. If you are running low boost (less than 8psi), you can get away without having any of this. Just a straight tube from the SC to the intake, but you better have strong claps and hose to withstand the surge pressrue during throttle closure.

I hope this helps!

 

No issues, just making sure everyone else understood what was going on with his car in case someone else runs into the same problem.