1. What is the 1/4 Mile Horsepower Formula?

The 1/4 Mile Horsepower Formula estimates a vehicle's horsepower based on its weight and elapsed time (ET) in a quarter-mile drag race. This calculation provides a useful approximation of engine performance.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Weight \) — Vehicle weight in pounds (lbs)
• \( ET \) — Elapsed time for 1/4 mile in seconds
• 5.825 — Empirical constant for the formula

Explanation: The formula shows that horsepower is proportional to vehicle weight and inversely proportional to the cube of elapsed time.

3. Importance of HP Calculation

Details: Estimating horsepower from 1/4 mile performance helps evaluate a vehicle's power-to-weight ratio and compare performance modifications.

4. Using the Calculator

Tips: Enter vehicle weight in lbs and 1/4 mile elapsed time in seconds. All values must be valid (weight > 0, ET > 0).

5. Frequently Asked Questions (FAQ)

Q1: How accurate is this calculation?
A: It provides a reasonable estimate but actual horsepower may vary due to traction, aerodynamics, and drivetrain losses.

Q2: Should I use curb weight or race weight?
A: For most accurate results, use the actual weight during the run including driver and fuel.

Q3: Does this account for different track conditions?
A: No, the formula assumes ideal conditions. Actual performance varies with temperature, altitude, and track preparation.

Q4: Can I use this for motorcycles?
A: Yes, but results may be less accurate for very lightweight vehicles.

Q5: What's a good 1/4 mile time?
A: Times vary by vehicle type, but sub-14 seconds is generally considered quick for production cars.