how superchargers work
1 Roots-type supercharger
The vanes of the Rootstype supercharger rotors look like two meshed cloverleaves in crosssection. In actuality, these meshed vanes may be several inches long, depending on application. Air is induced at the top, squeezed by the rotors and expelled into the combustion chamber, preferably via an intercooler.
2 Screw-type supercharger
The principle of the screwtype supercharger is much the same as the Roots version, but in this case the two rotors feature closely meshing screw profiles, in a tapered helix fashion. The tightly squeezed – and therefore compressed – air is discharged in the same manner as the Roots-type.
3 Centrifugal supercharger
The centrifugal supercharger is very different in operation to the Roots- and screw-type of supercharger. It is, however, a familiar-looking item, as it is essentially the output half of a turbocharger, but in this case, with the impeller driven by a belt or gear. Air enters at the centre of the impeller and is spun outwards. It is then slowed by the diffuser and exits, either via an intercooler, or straight into the inlet manifold.
3 1 Passage of air through a roots suPercharger diffuser vanes imPeller 2 fill side discharge side