Estimate vehicle engine horsepower using elapsed time (ET) method or trap speed method. Calculate engine power from quarter-mile performance data with vehicle weight and timing measurements.
This calculator estimates engine horsepower based on quarter-mile performance data using two established methods. The elapsed time (ET) method uses the time to complete a quarter mile, while the trap speed method uses the speed at the end of the quarter mile run.
Both methods provide reasonable estimates of engine power output based on real-world performance data. Results should be considered estimates as actual horsepower can vary significantly based on drivetrain efficiency, aerodynamics, and other factors.
Where: Weight = vehicle weight in pounds, ET = elapsed time in seconds for quarter mile
Where: Weight = vehicle weight in pounds, Speed = trap speed in MPH at quarter mile
| Vehicle Type | Typical ET (seconds) | Typical Trap Speed (MPH) | Estimated HP Range |
|---|---|---|---|
| Economy Car | 17-20 | 75-85 | 100-150 HP |
| Mid-size Sedan | 15-17 | 85-95 | 150-200 HP |
| Sports Car | 13-15 | 95-110 | 200-300 HP |
| Muscle Car | 12-14 | 105-120 | 300-450 HP |
| Supercar | 10-12 | 120-140 | 450-700 HP |
| Hypercar | 9-11 | 130-150 | 600-1000+ HP |
Drivetrain Loss: Automatic transmissions typically lose 18-25% of engine power, while manual transmissions lose 12-18%. These calculations estimate engine power, not wheel power.
Aerodynamics: Vehicle drag coefficient and frontal area significantly affect trap speed, especially at higher velocities. Streamlined vehicles may show higher calculated horsepower.
Traction: Wheel spin during launch reduces ET accuracy. Good traction and proper launch technique are essential for reliable measurements.
Track Conditions: Temperature, humidity, altitude, and track surface all affect performance. Cooler, drier conditions typically produce better times.
ET Method Advantages: More sensitive to launch and early acceleration, better for comparing overall vehicle performance including drivetrain efficiency.
Trap Speed Method Advantages: Less affected by launch technique, more directly related to engine power output at higher RPM ranges.
Best Practice: Use both methods and compare results. Significant differences may indicate measurement errors or unusual vehicle characteristics.
| Class | ET Range | Typical Modifications | Horsepower Range |
|---|---|---|---|
| Stock/Super Stock | 12-15 sec | Minor modifications | 200-400 HP |
| Comp Eliminator | 8-12 sec | Engine modifications | 400-700 HP |
| Super Comp | 8.90 sec index | Racing modifications | 500-800 HP |
| Top Sportsman | 6.0-7.99 sec | Full race preparation | 800-1200 HP |
| Pro Modified | 5.70-6.05 sec | Unlimited engine mods | 2500-4000 HP |
These formulas provide estimates based on empirical data and may not account for all variables affecting vehicle performance. Actual dyno-tested horsepower may vary ±15-20% from calculated values.
Best Results: Consistent track conditions, professional timing equipment, proper vehicle preparation, and experienced driver technique produce the most accurate horsepower estimates.