Quote:
Originally Posted by JoeFromPA
Have you seen the shaft size on many supercharger configurations? Granted, they are belt driven, but still - it's all about the engineering behind it.
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I am not sure what you want to imply... superchargers and turbos are very different animals.
A supercharger is mechanically connected to the engine so its speed is directly proportional to the engine speed regardless of load. A supercharger compressor spins at a much lower speed than a turbo and therefore needs to be much bigger to supply the same mass flow. Due the larger size of the compressor, the lower rotational speed and how it is driven, the inertia of the shaft has negligible impact on a supercharger.
Since a turbo is free spinning, inertia is extremely important for response time. With the high rotation speeds involved and the relatively small and light compressor and turbine wheels, the weight of the shaft is certainly not negligible here.
This is the reason we don't see that many (not to say none) "split" turbos on high performance applications out there. IMO, it is the avenue of the electric motor/generator on the turbo that allows this concept to work.