timbo wrote:The key difference is that supercharger takes power from crankshaft which taxes efficiency.
the superchargers that are mechanically driven in cars are inefficient, and give this so-called supercharging a bad name
because all superchargers with output in car-useful proportion to rpm are inefficient
the centrifugal/radial flow supercharger (as in the turbocharger) is efficient but has output poorly proportioned to rpm
that's why in cars it's mostly (excapt in failures like the V16 BRM and the Novi) driven by an exhaust turbine
whose wastegate etc gives an engine with better matched supercharging than the same driven mechanically
the centrifugal supercharger is just fine at steady rpm as in aircraft and industrial engines
the price in crankshaft power can be very small, and returned with profit by power increase with little increase in losses
the forward pressure (+dP) contributes to crankshaft power (just as in a turbocharged engine at +dP)
such lightly supercharged engines were the most efficient SI engines ever, and are selling today for running on 'fracking' gas
(all so-called turbocharged aircraft engines had a primary stage of such mechanically driven centrifugal supercharging)
not be confused with the heavily supercharged WW2 developments of very high power but tending to lower efficiency