Yeah, you can use put BOVs on Centrifugal superchargers. Roots blowers on the other hand pressurize there air directly in an intake plenum and it will all be used by the engine so there is no worry of surge.

 

Eh, not totally true... what about when you're engine braking at 7,000 RPM? Most (OEM) superchargers will have a bypass valve that dumps the air out of the intake manifold and back into the pre-throttle body air stream. It makes them way more efficient because the engine isn't fighting to make boost when it doesn't need to.

 

so the roots style supercharger doesnt need it b/c it already has a bypass valve...could you possibly put a bov in its place....

 

No. I actually misspoke in my last responce... the bypass valve just goes from one side of the supercharger to the other so when the throttle body is closed it pumps air in a circle instead of creating a vacuum.

There's no need or use for a blow off valve on any supercharger that has the throttle body before the compressor.