- Mechanical horsepower
- 285.6 hp
- Power
- 212.97 kW
How it works
Small speed errors grow when cubed
In the quarter-mile trap-speed model, entering a speed 10% too high increases estimated horsepower by 33.1% at unchanged race weight. Check the measured trap speed carefully; the cubic relationship magnifies an input error.
Comparing measured inputs with performance estimates
The torque-and-speed mode calculates power from mechanical inputs, while the quarter-mile mode infers a performance estimate under its stated model. These are different sources of information and need not agree. Review the vehicle weight and timing assumptions before interpreting a track-based estimate. The result is not a replacement for a controlled engine or chassis dynamometer measurement.
Torque & RPM: formula and assumptions
Mechanical horsepower = torque(lb-ft)×RPM/5252.113122.
Engine, wheel, and brake horsepower measurements are not interchangeable. This mode requires torque measured at the same RPM.
Quarter-mile performance estimate: formula and assumptions
ET method: hp = weight(lb) × (5.825/seconds)³. Speed method: hp = weight(lb) × (mph/234)³.
Historical empirical quarter-mile estimates. Elapsed time excludes reaction time and trap speed is not average speed. These inputs do not distinguish measured wheel power from exact crank power.
Worked example
Using the Torque & RPM example:
- Torque (lb-ft)
- 300
- Rotational speed (RPM)
- 5000
Mechanical horsepower = torque(lb-ft)×RPM/5252.113122.
Example result
Mechanical horsepower: 285.6 hp
Power: 212.97 kW
These are illustrative inputs. Change the values to explore a different scenario.
What to keep in mind
Quarter-mile performance modes use historical empirical coefficients and do not measure actual crank or wheel power.
Formula references
- NIST: Guide to the SI (opens in a new tab)
- Mopar Performance Parts: Jeep Engines, 3rd edition, printed page 495 (opens in a new tab)
- NIST Handbook 44, 2026, Appendix C (opens in a new tab)
References explain the underlying methods; they do not imply endorsement or individual professional review of Finflo.
Common questions
Does a quarter-mile estimate measure exact engine or wheel horsepower?
No. It is a historical empirical relationship, not a dynamometer measurement or a precise distinction between crank and wheel power.
Should reaction time be included in quarter-mile elapsed time?
No. Use elapsed time excluding reaction time. In the other mode, use measured trap speed rather than the run's average speed.
Prepared by Finflo. See our methodology and editorial policy.