Turbo Boost HP Calculator
Estimate the horsepower gain from turbo or supercharger boost based on your naturally aspirated power and boost pressure.
How it works
Boosted hp ≈ N/A hp × ((boost + 14.7) ÷ 14.7) × efficiency (14.7 psi = sea-level atmosphere)
Boost works by cramming more air into the cylinders, and power scales roughly with the mass of air the engine ingests. Adding boost raises the absolute pressure from one atmosphere (about 14.7 psi at sea level) to atmosphere plus boost, and the ratio of those two pressures is the rough multiplier on airflow and power. The efficiency factor trims the theoretical figure to account for the heat the compressor adds, pumping losses and imperfect intercooling. This is a first-order estimate only — the actual result hinges on the specific turbo’s efficiency, fuel supply, compression ratio and tune.
Worked example
Take a 200 hp naturally aspirated engine and add 7 psi of boost. The pressure ratio is (7 + 14.7) ÷ 14.7 ≈ 1.48. With a 0.90 efficiency factor, 200 × 1.48 × 0.90 ≈ 266 hp — a gain of roughly 66 hp over the naturally aspirated figure.
Frequently asked questions
How accurate is this boost horsepower estimate?
It is a rough ballpark. Power tracks airflow, but real gains depend on the turbo’s compressor efficiency, intercooling, fuel delivery and tuning. Use it to gauge the scale of a change, not to predict a dyno number.
Why does boost make so much heat?
Compressing air raises its temperature, which reduces its density and makes it more knock-prone. That is why boosted setups use intercoolers and why the efficiency factor in this estimate is below 1 — some of the theoretical gain is lost to heat.
Does more boost always mean more power?
Only up to a point. Beyond a turbo’s efficient range it adds more heat than air, fuel and octane become limiting, and engine internals set a safe ceiling. Doubling boost rarely doubles power in practice.
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Educational estimate. Real-world results vary with conditions, tuning and measurement.