1. What is a Speed And Gear Ratio Calculator?

Definition: This calculator estimates vehicle speed based on engine RPM, gear ratio, and a constant that accounts for tire size and other factors.

Purpose: It helps automotive enthusiasts and mechanics determine vehicle speed at specific RPMs for different gear ratios.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( S \) — Speed (miles per hour)
• \( RPM \) — Engine revolutions per minute
• \( GR \) — Gear ratio (unitless)
• \( C \) — Constant (typically 0.00595 for mph with standard tire size)

Explanation: The engine RPM is divided by the gear ratio to get wheel RPM, then multiplied by a constant to convert to speed.

3. Importance of Speed Calculation

Details: Accurate speed calculations help in gear selection, performance tuning, and understanding vehicle behavior at different RPM ranges.

4. Using the Calculator

Tips: Enter the engine RPM, gear ratio, and constant (default 0.00595 for mph). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What affects the constant value?
A: The constant is affected by tire diameter - larger tires increase the constant while smaller tires decrease it.

Q2: How do I find my gear ratio?
A: Gear ratios can be found in your vehicle's specifications or by dividing the number of teeth on the ring gear by the pinion gear teeth.

Q3: What's a typical gear ratio?
A: Final drive ratios typically range from 2.73 to 4.10 for passenger vehicles, with lower numbers favoring highway efficiency.

Q4: How accurate is this calculation?
A: It provides a theoretical speed. Actual speed may vary due to tire wear, slippage, and other factors.

Q5: Can I calculate RPM from speed?
A: Yes, rearrange the formula: RPM = (Speed × GR) / C