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Old 03-14-2008, 12:57 PM   #2
panic
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Re: Superchargers: Compressor Design and Choices

The analysis of the screw types has a serious and fundamental error. Quoting: "As the two rotors spin, the lobes interlock to form nearly airtight sections within the supercharger housing."

This does not happen - the rotors never interlock.

On all G.M.C., Roots, Eaton etc. the lobes interlock as they pass each other, but this is only for clearance - no work or pumping occurs between the 2 mating lobes. The working area is the volume between 2 sequential lobes on the same rotor and the case inner wall, and it's only moved (but not compressed).

On all screw types, the working area is the inter-lobe volume between the male and female rotors. It's larger at the intake end, and decreases along the length of the rotors until the exhaust port. This change in volume is the compression. If the rotors interlocked the compression would be infinite (except for safety clearance and leakage).
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