A supercharger is a belt or chain-driven compressor that creates a flow of pressurised air, fed directly into the intake. This "boosted" air fills the compression chamber with more air molecules that a normally aspirated engine whilst the combustion process remains identical to a normally aspirated engine.
Modern superchargers are generally simple devices and are capable of generating high numbers of engine horsepower. Their torque output is immense and essentially there is no throttle 'lag' or delay. Boost production is immediate and very linear from idle up to the redline. However they are generally not very efficient and require a relatively large amount of eccentric horsepower, between 15% and 50% to drive the blower sufficiently enough to create an adequate cubic feet per minute (CFM) increase. Because of this, supercharged rotary engines rarely exceed 300whp without really pushing the levels of boost
Cooling the pressurised air can also be a challenge with some systems (such as Pettit) using a liquid-to-air heat exchanger to combat this. Belt-drive superchargers can also stress and distort the front shaft extension of the eccentric shaft, more commonly on older rotary engines where their thrust bearings are smaller and cannot resist the increased loads.
Superchargers can be excellent performers but come at the cost of efficiency. Whilst If you want the most efficient form of forced induction, you should consider a turbocharger.
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