supercharging

Supercharging is a method of forced induction used to increase an internal combustion engine’s power by compressing the intake air. A supercharger raises air density before it enters the combustion chamber, allowing more fuel to be burned and producing more power and torque than naturally aspirated operation. The boost is measured as manifold pressure above ambient, typically in psi or bar.

Unlike a turbocharger, which is driven by exhaust gas and can exhibit lag, a supercharger is powered directly by the engine through a belt, shaft, or gears. This usually provides immediate throttle response because boost is available as soon as the engine is turning. However, because the compressor draws power from the engine, superchargers introduce a parasitic loss that can reduce overall efficiency unless the engine is tuned to benefit from the increased air charge.

Common types include positive-displacement units such as Roots-type and twin-screw (scroll/twin-rotor), which deliver strong low- to mid-range boost and add a predictable response. Centrifugal superchargers resemble small turbochargers in operation, delivering boost more progressively with RPM and often achieving higher ultimate boost at high speeds but requiring higher engine speeds to produce meaningful pressure.

Intercooling is frequently used with turbochargers and superchargers to lower the compressed air’s temperature, increasing density and reducing the likelihood of knock. Applications span performance cars, trucks, and some aircraft engines; in aviation, turbochargers are more common for maintaining power at altitude, while superchargers provided reliable pressure at lower to mid-altitudes.

Modern developments include electrically driven superchargers, which aim to combine the immediate response of traditional supercharging with reduced parasitic losses during certain operating conditions.