1. What are Horsepower and Torque?

Horsepower: A measurement of power representing the rate at which work is done (1 HP = 550 foot-pounds per second).

Torque: A measurement of rotational force (twisting force) typically measured in pound-feet (lb-ft).

2. The Relationship Between HP and Torque

The fundamental formula connecting horsepower and torque:

Where:

• \( HP \) — Horsepower
• \( Torque \) — Rotational force in pound-feet (lb-ft)
• \( RPM \) — Revolutions per minute of the engine
• 5252 — Conversion constant (derived from units conversion)

Key Insight: At 5,252 RPM, horsepower and torque values are always equal numerically.

3. Practical Differences

Torque: Determines a vehicle's pulling power and acceleration at low speeds.

Horsepower: Determines top speed and ability to maintain speed under load.

4. Using the Calculator

Tips: Enter torque in lb-ft and engine speed in RPM to calculate horsepower. Both values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Which is more important, horsepower or torque?
A: It depends on application. Torque matters for towing/hauling, while horsepower matters for high-speed performance.

Q2: Why does the formula have 5252?
A: This constant comes from unit conversions (1 HP = 550 ft-lb/sec, and converting minutes to seconds).

Q3: Can you have high torque but low horsepower?
A: Yes, if the engine operates at low RPMs (like diesel trucks). Horsepower increases with RPM.

Q4: How do electric motors compare?
A: Electric motors produce maximum torque at 0 RPM, giving instant acceleration.

Q5: What's a typical torque-to-horsepower ratio?
A: Gas engines often have 0.8-1.2 lb-ft torque per HP. Diesels may have 1.5-2+ lb-ft per HP.