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I doubt it would work very well because the mass, and inertia, of the Roots impellers would make them very slow to spool up if driven by exhaust gases. It would be very laggy. Turbocharger impellers, on the other hand, are very lightweight and more readily spun by gasses. |
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centrifugal compressors are more effcient anyway.
also screw and roots types are much slower spinning. its a mismatch |
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Also a point against: pd superchargers pump a certain volume of air per revolution, if you make that volume twice what the engine would process than you have 2:1 pressure ratio, 1 bar, 15 psi of boost (take your pick) no matter what engine speed you are at. centrifugal compressors (regardless of how they are powered, either by exaust heat or by mechanical energy) produce pressure depending on the square of their speed, so not only would it be laggy because it would take more energy to spin heavy lumpy rotors it would be even more so because it would not even let air in (not to even mention force it in) un till the turbo spooled halfway to max speed. |
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AND it you want the benefits of both pd supercharging and turbos just use both. alfa has done it long ago, turbo magazine has done it recently. a series of articles called project mr6. |
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Also, most superchargers don't spin at near the speed of the turbine side of the turbo due to the larger mass of the screws. The turbine side has to spin fast in order to get the energy out of the exhaust since there is very little pressure drop across a turbine because too much back pressure would actually be harmful. |
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to me it sounds like u have more weight to spin and you are spining them in different directions. to me not a good idea. but test it out and see |
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