Originally Posted by Mort

STS told me that compressor surge was not that big of a problem unless you are making 12 - 15 PSI of boost. Then it is very hard on the compressor fins and maybe the shaft. You will never get rid of compressor surge all together because of the delay in the BOV operation. If you have a compressor that creates surge when you abruptly close the throttle then you will always have some AFAIK.

When you close the throttle the engine goes into deceleration and creates enough vacuum to open the BOV. I have to close the throttle completely for the engine to generate enough vacuum to open the BOV on the 6.0L. The spring in the STS TiAL BOV is set at -11 psi and the vacuum in my engine goes to -11.XX psi under deceleration. This should open the BOV and vent the excess pressure generated by the compressor and closed throttle plate to the atmosphere. It takes a second for this to happen so you will still get a little compressor surge before the BOV opens and allows the pressure in the intake to vent. I still hear some compressor surge and have a hard time hearing anything from the BOV from inside the truck. I assume it is working properly and reducing the pressure and abuse on the compressor fins and throttle plate but just that it has a little lag in it's operation.