Vehicle Engine Horsepower Calculators

o calculate engine horsepower using the Trap Speed and ET (Elapsed Time) methods, here are the basic steps and formulas:

1. Engine Horsepower Using the Trap Speed Method

The Trap Speed Method calculates horsepower based on the vehicle's terminal speed (trap speed) in the quarter-mile (or any other race distance) and the weight of the vehicle.

Formula:

Where:

• Vehicle Weight = Total weight of the vehicle in pounds (including driver and all equipment).
• Trap Speed = The speed at the end of the quarter-mile, measured in miles per hour (mph).
• The constant "234" is a calibration factor for the trap speed method in standard conditions.

2. Change in Engine Horsepower Using the Trap Speed Method

To calculate the change in horsepower after making modifications to the vehicle, you can use the difference in trap speeds before and after the modification.

Formula:

Where:

• The weight of the vehicle stays the same for both the old and new conditions.
• The change in horsepower depends on the cubic difference in trap speeds.

3. Engine Horsepower Using the ET Method

The ET Method estimates horsepower based on the vehicle's elapsed time (ET) in the quarter-mile.

Formula:

Where:

• ET = The time it takes to cover the quarter-mile in seconds.
• Weight = The total weight of the vehicle in pounds (including driver and all equipment).
• The constant "1.43 × 10⁶" is used to calibrate the ET method to standard conditions.

4. Change in Engine Horsepower Using the ET Method

For estimating the change in horsepower after modifications, use the difference in ET before and after the modifications.

Formula:

This formula calculates the difference in horsepower based on the cubic change in ET, which indicates a performance change.