Centrifugal Superchargers

A centrifugal supercharger is basically the same type of pump as the compressor side of a turbocharger, but is mechanically driven off the crankshaft instead of by exhaust gas. Internal gearing steps up the spin speed, and gives a distinctive whistling sound. The centrifugals type of compressor, like the turbos, is efficient only at high rpm. Because all superchargers by definition are under continual drive from the crank (i.e. with no comparable turbocharger wastegate system to cut the drive), design decisions set the limits to how much internally to gear-up (overdrive) the spooling. The centrifugal supercharger aims for high-end boost which builds exponentially in the upper half of the powerband, generally they start boosting around 2000 to 3000 rpm, and attain full boost at max rpm.