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Pressurizing the intake charge of an engine is a sure-fire way to make more power, and many enthusiasts will say there are two options for achieving this goal—turbocharger or supercharger. The fact of the matter, however, is there’s more nuance to it than that. Jason Fenske of Engineering Explained on YouTube dove into the minutia of four types of superchargers in his latest video.
In it, Fenske both compares and explains each of the four supercharger types. In his signature whiteboard style, he outlines how a roots, twin-screw, centrifugal, and electric (yes, really) supercharger functions. Despite accomplishing the same task, each does it slightly differently, and therefore there will forever be debate about which is best.
The first—and probably best-known—style is roots, which uses two rotors to capture air and pass it into the intake manifold. The second version is very similar to the roots design, but the rotors take a different shape. The twin-screw design evolves the roots design to shape the rotors into complimentary shapes so that the air is compressed as the rotors turn. Both of these designs are positive displacement, which means that they displace a fixed amount of air per revolution—and thus move the torque curve of an engine up across the board.
The other two variations on the supercharger theme are not positive displacement, meaning they take what the torque curve and make it a steeper slope as rpms climb. While it is technically two different types, the centrifugal and electrical are extremely similar. The key difference is the method of spinning the compressor wheel—either the engine’s crankshaft or an electric motor. The inefficiency of the electric supercharger is eclipsed by the convenience of having it spool up boost on demand—so long as you have a sufficient battery charge.
The debate on which is best will persist forever. The simple why-can’t-we-all-get-along response is that they are simply tools to accomplish specific tasks. Any toolbox should have more than one style of pliers, and when engineers have access to four types of superchargers, we enthusiasts stand a better chance of getting our hands on a factory car that whines when we hit the loud pedal. The aftermarket is no different. Determine which is best for your specific project and go out in the garage and get it installed.