Supercharger Basics

A supercharger does the same job as a turbocharger — forces more air into the engine than it can breathe naturally — but it is driven mechanically by a belt connected to the crankshaft instead of by exhaust gas. This means the supercharger provides boost the instant you press the throttle with no delay. The trade-off is that spinning the supercharger takes power from the engine — typically 50 to 100 horsepower on larger applications — but the net power gain is still significant because the additional air allows much more fuel to be burned.

Roots type — two meshing lobes push air into the intake manifold. This is the classic design you see sitting on top of muscle car engines. Simple, reliable, produces boost immediately, but generates more heat than other designs. Twin-screw — similar appearance to Roots but the internal screws actually compress the air inside the housing before delivery. More efficient and produces cooler air than Roots. Centrifugal — looks like a turbo compressor driven by a belt instead of exhaust. Boost increases with RPM rather than being available immediately. Most efficient of the three types but does not produce as much low-RPM response.

Belt wear and tension — the drive belt on a supercharger handles significant load. A worn or slipping belt reduces boost and produces a squealing noise under acceleration. Intercooler coolant level on liquid-cooled supercharger systems — a separate coolant circuit cools the supercharger's intercooler and must be maintained. Internal bearing or coupler wear produces a whining noise that increases with engine RPM.