Screw Air Compressor

In a rotary screw compressor, air enters the compressor and is trapped between matching rotors and compressed. Perhaps the most popular type of rotary screw compressor is the oil flooded type.

Superchargers

The twin-screw type supercharger or twin-screw blower is a positive displacement type device that operates by pushing air through a pair of meshing close-tolerance screws similar to a set of worm gears.

Twin-screw superchargers are also known as Lysholm superchargers (or compressors) after its inventor Alf Lysholm.

Comparative advantages

The rotary screw compressor has low leakage levels and low parasitic losses vs. roots-type. The supercharger is typically driven directly from the engine's crankshaft via a belt or gear drive. Unlike the Roots type supercharger, the twin-screw exhibits internal compression which is the ability of the device to compress air "within" the housing as it is moved through the device instead of relying upon resistance to flow downstream of the discharge to establish an increase of pressure.

The requirement of high-precision computer-controlled manufacturing techniques makes the screw type supercharger a more expensive alternative to other forms of available forced induction. With later technology, manufacturing cost has been lowered while performance increased.

All supercharger types benefit from the use of an intercooler to reduce heat produced during pumping and compression.