1. What Is Power-to-Weight Ratio?

The Power-to-Weight Ratio (PWR) is a measurement of performance that compares the power output of an engine to the weight of the vehicle. It's commonly used in automotive and motorsports applications to evaluate a vehicle's potential performance.

2. How Does the Calculator Work?

The calculator uses the simple PWR formula:

Where:

• \( Power \) — Engine power in horsepower (hp)
• \( Weight \) — Vehicle weight in pounds (lb)

Explanation: The ratio shows how much power is available to move each pound of vehicle weight, with higher ratios indicating better potential acceleration and performance.

3. Importance of PWR Calculation

Details: PWR is crucial for comparing vehicle performance potential, especially in racing applications where small differences can significantly impact results.

4. Using the Calculator

Tips: Enter power in horsepower and weight in pounds. Both values must be greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is a good power-to-weight ratio?
A: For street cars, 0.06 hp/lb is decent, 0.08 is good, and 0.10+ is excellent. Race cars often exceed 0.15 hp/lb.

Q2: How does PWR affect performance?
A: Higher PWR generally means better acceleration and hill-climbing ability, assuming similar traction and aerodynamics.

Q3: Can I use different units?
A: Yes, but the ratio will be different. Common alternatives are kW/kg (1 hp/lb ≈ 1.64 kW/kg).

Q4: Why not just compare horsepower?
A: A heavy car with high horsepower may be slower than a light car with moderate horsepower. PWR gives more meaningful comparison.

Q5: Does PWR account for drivetrain loss?
A: No, this calculates theoretical ratio. For wheel horsepower, use dyno-measured power instead of engine rating.