Superchargers will let air thru when the helical rotors are not turning, iff you wanted you can and could doo the mad max,,cuztomcarbuilder said:I know I am going to get bashed on this one....BUT a Nissan Skyline has a clutch operated supercharger and a turbocharger. They use the supercharger to kill the LAG and then when the RPM's and boost come up the computer shuts off the supercharger, switches plenums, and closes the wastegate valve on the Turbo. But what everone says here is true, The Skyline is the only clutch style supercharger that I know of.
Oh and for the record....If you shut off the supercharger without switching the plenums you would choke off the engine. It would be just like butterflies closing on a carb when you let off the throttle.