Automotive
Torque, horsepower, fuel economy, tire sizing, exhaust flow, intake, injector, and turbo sizing tools.
37 tools available
Automotive tools handle the performance and sizing maths behind engines and drivetrains: horsepower and torque, fuel economy, tyre dimensions and speedometer error, gear ratios, compression, displacement, and the airflow calculations for intakes, injectors, exhaust, and turbos. They translate raw measurements into the numbers enthusiasts and mechanics actually use to make decisions.
A few relationships tie it all together. Power and torque are linked by engine speed (hp = torque × rpm ÷ 5252), which is why those two curves always cross at 5,252 rpm. Tyre size changes rolling diameter, which throws off your speedometer and effective gearing. Airflow ultimately caps power, so injector and turbo sizing must match the target. These calculators make those dependencies explicit so a mod in one place can be checked against everything it affects — all computed locally in your browser.
Key automotive formulas
| Calculation | Formula | Notes |
|---|---|---|
| Horsepower | hp = T × rpm ÷ 5252 | T in lb-ft |
| Displacement | V = π/4 × bore² × stroke × cyl | Swept volume |
| Tyre diameter | d = rim + 2 × (width × ratio) | From the sidewall size |
| Speedo error | %Δ = (new − old) ÷ old | From rolling diameter |
Power and torque curves always intersect at 5,252 rpm — a direct consequence of the horsepower formula.