On my brothers 12 valve w/a 0 plate 4" straight pipe and bhaf after he does a hard accel. run and lets off the throttle the intake will kinda go pop pop pop real fast. Is this some kind of overboost or backpressure?? We have the wastegate elbow in also.

Chris

 

Sounds like what is referred to as turbo bark...........don't lift so fast under high boost conditions.

Bob

 

I will let him know

Thanks

Chris

 

I am always intersted in why things do what they do. Maybe this will help. Under high load you have pressurized with compressed air everything from the outlet of the compressor housing through the air-to-air cooler into the engine. When you let off the throttle quickly there is no more exhuast heat to drive the the turbo. All that boost you were just building now wants to take the path of least resistance and come back through the turbo and out the intake. As it comes back through the turbo it is trying to slow the wheel down very fast. Thus the barking noise. Not such a great thing for turbos. I have seen large industrial turbos shear the wheel off the shaft when this happens.

 

Yup, chuffing or bark sounds kindof cool, but it can cause your engine to have compressor wheel for lunch.