1. What is Power to Weight Ratio?

The Power to Weight Ratio (PWR) is a performance metric that compares a vehicle's power output to its weight. It's commonly used in automotive and motorsport applications to estimate acceleration potential and overall performance.

2. How Does the Calculator Work?

The calculator uses the power to weight equation:

Where:

• \( Speed \) — Quarter mile speed in miles per hour (mph)
• \( Time \) — Quarter mile time in seconds (s)
• \( Weight \) — Vehicle weight in pounds (lbs)

Explanation: The equation estimates the power to weight ratio based on quarter mile performance, with speed being cubed to account for the exponential increase in power needed to overcome air resistance at higher speeds.

3. Importance of Power to Weight Ratio

Details: Power to weight ratio is a key indicator of a vehicle's performance potential. Higher ratios generally mean better acceleration and higher top speed capability.

4. Using the Calculator

Tips: Enter your quarter mile speed in mph, quarter mile time in seconds, and vehicle weight in pounds. All values must be greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is this calculation?
A: This provides a good estimate but actual power to weight may vary based on traction, aerodynamics, and drivetrain losses.

Q2: What's a good power to weight ratio?
A: For street cars, 0.05-0.08 hp/lb is good, 0.08-0.12 is excellent, and race cars often exceed 0.15 hp/lb.

Q3: Can I use metric units?
A: This calculator uses imperial units (mph, lbs). For metric, convert km/h to mph and kg to lbs before calculation.

Q4: Does this account for drivetrain loss?
A: No, this calculates wheel power to weight ratio. For engine power, you'd need to estimate drivetrain losses separately.

Q5: Why is speed cubed in the equation?
A: Air resistance increases with the square of speed, and power needed to overcome it increases with the cube of speed.