Supercharger Boost Calculator

A supercharger compresses the air entering the engine, allowing it to consume more fuel and produce more power. It's driven by a belt connected to the engine, using a small amount of engine power but producing significantly more in return.

Pulley ratio is the crank pulley diameter divided by the supercharger pulley diameter. This ratio determines how fast the supercharger spins relative to engine RPM, directly affecting boost pressure and power output.

Boost pressure depends on pulley ratio, engine RPM, supercharger displacement, efficiency, and ambient conditions. Our calculator uses the formula: [(Supercharger Displacement × Supercharger RPM × Efficiency) ÷ (Engine Displacement × 1728)] × Ambient Pressure - Ambient Pressure.

Most modern superchargers operate between 60-80% efficiency. High-end units like Roots-type or centrifugal superchargers can achieve 70-85% efficiency, while older designs may be around 60-70%.

Excessive supercharger RPM can lead to reduced efficiency, increased heat generation, and potential damage to the supercharger internals. Most superchargers have maximum RPM limits that should not be exceeded.

Higher ambient pressure (lower altitude) allows for higher boost levels, while lower ambient pressure (higher altitude) reduces achievable boost. Sea level ambient pressure is typically 14.7 PSI.

This calculator is specifically designed for superchargers, which are mechanically driven. Turbochargers operate differently as they're exhaust-driven and have different efficiency characteristics and boost control methods.

Engine displacement is the total volume of all cylinders, while supercharger displacement is the volume of air the supercharger can move per revolution. The ratio between these affects boost pressure generation.