Quote:
Originally Posted by serialk11r
Sorry man you're not exactly right.
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Right back at you.
They
are both positive displacement, meaning they'll move a more or less fixed amount of air per revolution (volumetric efficiency not withstanding). But they don't work in exactly the same way. A roots blower simply moves air from from the top of the blower to the bottom, and once that air reaches the bottom the blower crams it in creating pressure.
A twin screw compressor moves air from the back to the front in an ever shrinking chamber. The air is compressed as it travels along the length of the supercharger, this is the 'internal pressure ratio' which is usually 1.4:1, though Kenne Bell makes some that will do 2:1. When the air is discharged into the intake plenum it is already compressed, and that was done in a more efficient manner than a roots blower is capable of (lower temps).
