Turbochargers and superchargers are two cousins used for power enhancement. they both improve the performance of the car but do it in different ways. this would be elucidated as we delve deeper into them.
Turbocharger: These are basically a turbine which is provided at the exhaust manifold. it uses the kinetic energy of the burnt charge and boost the charging pressure of the intake manifold. Using the turbocharger the volumetric efficiency of an engine can cross 100% which is really a boon for performance engines. the increase in pressure which is normally calls ‘BOOST’ is the increase in pressure of the cylinder at the end of the intake stroke. The interesting thing to note about the turbocharger is that the RPM of the turbine can go ridiculously high up to the tune of 200000 RPM.
Supercharger: These are also turbines that use the crankshaft rotation to rotate the turbine on the intake manifold.As the turbine draws power directly from the crankshaft, it has a parasitic effect on the engine. As the crankshaft is rotating the turbine the RPMs don’t go to exorbitant levels, the max it spools is to the range of around 50000 RPM. and because the rotation of the turbine is lower than the turbine of Supercharger, the boost pressure is also lower.
From this preliminary investigation it comes out that the turbocharger is a sure winner, so what’s the point of using a supercharger which has a parasitic effect on the engine and even then doesn’t provide as high boost?
The answer to this question lies deeper in the cause and effects of having either systems.
The turbocharger surely uses the kinetic energy of the exhaust gas which would anyway get dumped, but that comes at a cost, the cost it pays is the back pressure generated because of the obstruction of the exhaust flow. on the other hand, the supercharger does have a parasitic effect on the engine but the increase in power it provides well compensates for the losses.
One more point of consideration is the charging mechanism of the engines.
Supercharger would definitely be better for petrol engines for 2 reasons
a) it runs at a higher RPM
b) The amount of charge depends on the load on the engine.
Turbocharger would be better for Diesel engines because the mass flow rate of the gasses (mostly air) remains the same for all the loads (its only the amount f fuel injected that matters).