Roots Vs. Centrifugal
Before we proceed, it is important to understand the different styles of superchargers that are available. There are basically three types: centrifugal, Roots, and screw-type. We’ll concentrate on the most popular, which are the centrifugal and Roots-style blowers.


Centrifugal superchargers are similar to turbochargers in many ways. However, centrifugal superchargers are actually driven by a belt off the engine, while a turbocharger is exhaust driven. Centrifugal superchargers rely on an internal impeller to step up boost. Because boost depends on how fast the impeller spins, these units generally do not create as much boost at low rpms, because the impeller is not spinning fast enough. However, if your vehicle already produces good low-end power and torque, a centrifugal blower is the best choice for maximizing high rpm power.

Roots-type superchargers, like the ones offered by Jackson Racing, are simply large air pumps. A Roots-type blower pulls in air and compresses it in the engine's cylinders. The speed at which the supercharger fills the cylinders depends on how quickly it is driven by a pulley and drive belt. The main drawback to Root-style superchargers is the consistency of the air charge. While centrifugal superchargers provide smooth, continuous airflow, the Roots blowers feed air into the engine in lumpier, inconsistent bursts, thereby slightly reducing efficiency. However, Roots-type blowers produce a flatter torque curve with linear power across the rpm range, making it the ideal choice for adding throttle response and streetable low-end power. Roots-style superchargers are also generally less expensive than their centrifugal counterparts.

Boost Review
Boost is the amount of air pressure created by the supercharger and is mainly the function of engine displacement and blower drive speed.

Because higher boost means more power, many enthusiasts look for ways to bump up their boost levels. You can increase boost by swapping out the existing supercharger pulley for a smaller pulley, which drives the supercharger faster. It is important to remember, though, that the amount of boost that you can safely run is limited by the compression ratio of your engine. Too much boost can lead to detonation, which can destroy your motor.

Many supercharger manufacturers give their unit a boost range. This is a ballpark figure of the amount of boost you can expect using the standard pulley included with the supercharger. By making some engine modifications you can assure yourself that your boost level will land on the high end of this scale—or higher.