1slow370

No hard feelings guy but much of the earlier response is wrong

centrifugal's are not positive displacement guy they are a dynamic supercharger meaning that they flow different amounts of air compared to engine rpm. Positive displacement superchargers pump the same amount of air relative to engine rpm (almost). Positive displacemnts are generally preferred as the power and torque produced is made at nearly the same time as the power and torque curves were before supercharging so it feels more linear.

Centrifugal's produce almost no power in the lower rpms but it steadily builds creating a take-off feeling compared to the instant bang of pos. displacement. Centrifugal superchargers are generally cheaper than a twin screw but more expensive than a roots.

Centrifugal: Vortech, Rotrex, Paxton, Procharger

Twin-screw:Whipple, Vortech VTS, Eaton made OEM Lysholm, Kenne Bell

Roots:Weiand, Magna-charger(resells Eaton chargers for the aftermarket including the Eaton Twin Vortices Series or TVS, Eaton made OEM

There are other types of superchargers mainly used by volkswagen but they suck and are expensive so hell if i am mentioning them.

Edit: As to why twin-screw and roots are not the same they have totally different types of rotors inside them and while a twin screw actually compresses the air inside it like a piston a roots blower just pushes it into the manifold where it jams up against the valves and makes pressure there.

Positive displacement is like putting in a big v8, where as centrifugals are like high horse power 4 cylinders- they make power higher in the driving range.