1. What is the Gear Ratio Equation?

The gear ratio equation calculates the optimal gear ratio for drag racing based on your engine's RPM at the finish line, tire diameter, and trap speed. This helps racers optimize their final drive ratio for maximum performance.

2. How Does the Calculator Work?

The calculator uses the gear ratio equation:

Where:

• \( RPM \) — Engine revolutions per minute at trap speed
• \( tire\_dia\_in \) — Tire diameter in inches
• \( MPH \) — Vehicle speed at finish line (trap speed)
• \( 336 \) — Constant to convert units

Explanation: The equation determines the gear ratio needed to achieve a specific RPM at a given speed with particular tire size.

3. Importance of Gear Ratio Calculation

Details: Proper gear ratio is crucial for drag racing performance. It ensures your engine operates in its optimal power band at the finish line for maximum acceleration.

4. Using the Calculator

Tips: Enter your engine RPM at the finish line, tire diameter in inches, and trap speed in MPH. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Where do I get my trap RPM and MPH?
A: These values should be recorded from your time slip or data logger during a full pass down the drag strip.

Q2: How do I measure tire diameter?
A: Measure from the ground to the top of the tire and multiply by 2, or use manufacturer specifications for your specific tire size.

Q3: What is a typical gear ratio for drag racing?
A: Most drag cars use ratios between 3.50:1 and 4.56:1, but optimal ratio depends on your specific combination.

Q4: Does this account for torque converter slip?
A: No, this calculation assumes no slip. For automatic transmissions, you may need to adjust for actual converter slip percentage.

Q5: What if my calculated ratio isn't available?
A: Choose the closest available ratio from your manufacturer, or consider combining different transmission and rear-end ratios.