1. What is Crank vs Wheel Horsepower?

Definition: This calculator estimates engine (crank) horsepower based on measured wheel horsepower and drivetrain loss percentage.

Purpose: It helps automotive enthusiasts and professionals understand the relationship between engine output and actual power delivered to the wheels.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( CHP \) — Crank Horsepower (engine output)
• \( WHP \) — Wheel Horsepower (measured at wheels)
• \( DTL \) — Drivetrain Loss factor (typically 0.12-0.15 for RWD, 0.15-0.20 for FWD, 0.20-0.25 for AWD)

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

3. Importance of Horsepower Calculation

Details: Understanding drivetrain loss helps in vehicle performance tuning, comparing dyno results, and evaluating modifications.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What's typical drivetrain loss for different drivetrains?
A: RWD: 12-15%, FWD: 15-20%, AWD: 20-25%. Manual transmissions generally have slightly lower loss than automatics.

Q2: Why is wheel horsepower less than crank horsepower?
A: Power is lost through the transmission, differential, driveshafts, and other drivetrain components.

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

Q4: Can I use this for electric vehicles?
A: No, EVs have much lower drivetrain losses (typically 5-10%) due to fewer moving parts.

Q5: Where can I measure wheel horsepower?
A: At a performance shop with a dynamometer (dyno). There are chassis dynos for WHP and engine dynos for CHP.