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Boost Horsepower Calculator
Estimate horsepower gain from boost pressure
Boost horsepower estimation scales a naturally aspirated engine's power by its boost pressure ratio, discounted by system efficiency.
Formula: HP ≈ NA HP × ((14.7 + boost) ÷ 14.7) × efficiency — pressure-ratio estimate
What this number means
This estimates horsepower under boost from a naturally aspirated baseline and boost pressure, allowing for the fact that real systems do not achieve perfect pressure-ratio gains. Intercooling, turbo or blower efficiency and backpressure all pull the real number around.
What to change next
Use it to sanity-check a boost target against your fuel system and octane before turning anything up — the fueling requirement rises with the power. If actual power falls far short of the estimate, look for boost leaks, restriction or heat soak.
Worked example
An engine making 420 hp naturally aspirated at 10 psi of boost gives ≈ 620 hp at a typical 88% system efficiency (≈ 706 hp by ideal pressure ratio alone).