1. What is a Rear Wheel HP to Flywheel HP Calculator?

Definition: This calculator estimates the engine's flywheel horsepower (FHP) based on measured wheel horsepower (WHP) and drivetrain loss factor.

Purpose: It helps automotive enthusiasts and professionals estimate engine power from dyno measurements.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( FHP \) — Flywheel horsepower (engine output)
• \( WHP \) — Wheel horsepower (measured at wheels)
• \( DTL \) — Drivetrain loss factor (typically 0.12-0.15 for RWD)

Explanation: The formula accounts for power lost through the drivetrain between the engine and wheels.

3. Importance of Flywheel HP Calculation

Details: Understanding true engine power helps in performance comparisons, tuning, and vehicle modifications.

4. Using the Calculator

Tips: Enter your dyno-measured wheel horsepower and estimated drivetrain loss (default 0.15 for 15% loss). DTL must be between 0-0.5.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical drivetrain loss factor?
A: RWD vehicles: 12-15%, FWD: 10-12%, AWD: 20-25%. Manual transmissions typically have slightly lower loss than automatics.

Q2: Why is WHP lower than FHP?
A: Power is lost through the transmission, differential, axles, and other drivetrain components.

Q3: How accurate is this calculation?
A: It provides a good estimate, but actual drivetrain loss varies by vehicle condition, temperature, and dyno type.

Q4: Can I use this for electric vehicles?
A: No, EVs typically have much lower drivetrain losses (often under 5%).

Q5: Where can I measure my WHP?
A: Performance shops with dynamometers can measure your vehicle's wheel horsepower.