HP Planning Estimator

A constraint-based planning tool for turbo airflow, injector capacity and a user-editable baseline power assumption. It is not a dyno model.

Estimator

Engine familySelects reference cylinder count, BSFC and an editable baseline assumption.

Reference baseline crank HPOverride this with a verified value for the exact donor/configuration.

Turbo airflow classApproximate compressor airflow class.

Injector sizecc/min per injector.

Boostpsi gauge pressure.

FuelOnly a simplified planning adjustment; tune for actual fuel.

Drivetrain lossPercent used only to convert estimated crank range to wheel range.

Crank estimate

—

Wheel estimate

—

Modeled limiter

—

What this tool can and cannot tell you

The tool compares three simplified constraints: compressor airflow, injector fuel mass capacity and a pressure-ratio scaling model based on the baseline horsepower you enter. It takes the lowest modeled constraint to avoid presenting every added pound of boost as guaranteed power.

The result is a sanity-check range. Volumetric efficiency, compressor efficiency, intercooler effectiveness, exhaust backpressure, cam timing, ignition timing, air/fuel ratio, fuel quality, engine condition and dyno/test method all change real output. Use actual logs and a qualified calibration process for the car.

Injector correction

The injector model converts cc/min to lb/hr using an approximate gasoline-reference conversion of about 10.5 cc/min per lb/hr, then applies cylinder count, duty cycle and BSFC. The prior version of this site used an incorrect cc/min-to-lb/hr conversion; this rebuild corrects that calculation.