ProCharger D1SC centrifugal supercharger
Twin-Screw Superchargers A twin-screw supercharger operates by pulling air through a pair of meshing lobes that resemble a set of worm gears. Like the Roots supercharger, the air inside a twin-screw supercharger is trapped in pockets created by the rotor lobes. But a twin-screw supercharger compresses the air inside the rotor housing. That's because the rotors have a conical taper, which means the air pockets decrease in size as air moves from the fill side to the discharge side. As the air pockets shrink, the air is squeezed into a smaller space. Twin-screw superchargers are the most commonly ones installed on Corvettes because of their efficiency and relative light weight. This makes twin-screw superchargers more efficient, but they cost more because the screw-type rotors require more precision in the manufacturing process. Some types of twin-screw superchargers sit above the engine like the Roots supercharger. They also make a lot of noise. The compressed air exiting the discharge outlet creates a whine or whistle that must be subdued with noise suppression techniques. Centrifugal Superchargers A centrifugal supercharger powers an impeller – a device similar to a rotor – at very high speeds to quickly draw air into a small compressor housing. Impeller speeds can reach 50,000 to 60,000 RPM. As the air is drawn in at the hub of the impeller, centrifugal force causes it to radiate outward. The air leaves the impeller at high speed, but low pressure. A diffuser – a set of stationary vanes that surround the impeller – converts the high-speed, low-pressure air to low-speed, high- pressure air. Air molecules slow down when they hit the vanes, which reduces the velocity of the airflow and increases pressure. Centrifugal superchargers are the most efficient and the most common of all forced induction systems. They are small, lightweight and attach to the front of the engine instead of the top. They also make a distinctive whine as the engine revs up – a quality that may turn heads out on the street. 
Twin-screw supercharger
Centrifugal supercharger