1. What is a 1/4 Mile Drag Calculator?

Definition: This calculator estimates the horsepower of a vehicle based on its weight and 1/4 mile elapsed time (ET).

Purpose: It helps automotive enthusiasts and racers determine the approximate horsepower of their vehicles after a drag strip run.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( HP \) — Horsepower
• \( W \) — Vehicle weight (pounds)
• \( ET \) — Elapsed Time for 1/4 mile (seconds)

Explanation: The formula relates a vehicle's weight to its acceleration capability (ET) to estimate engine power output.

3. Importance of Accurate Measurements

Details: For best results, use actual scale weight (with driver) and precise 1/4 mile times from professional timing equipment.

4. Using the Calculator

Tips: Enter the vehicle weight in pounds (including driver) and the 1/4 mile elapsed time in seconds. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is the constant 5.825 used?
A: This empirical constant accounts for typical drag racing conditions and has been refined through years of racing data.

Q2: How accurate is this calculation?
A: It provides a reasonable estimate (±5-10%) for most street and race cars, but doesn't account for traction, aerodynamics, or drivetrain losses.

Q3: Should I use curb weight or race weight?
A: Always use actual race weight including driver, fuel, and any additional weight in the car during the run.

Q4: Does this work for motorcycles?
A: Yes, but the calculation may be less accurate for very lightweight vehicles with different power-to-weight ratios.

Q5: What if my car has wheelspin at launch?
A: The calculation assumes proper traction. Significant wheelspin will make the ET longer and the calculated HP lower than actual.