1. What is the HP (Torque × RPM) Calculator?

Definition: This calculator computes horsepower based on torque and RPM using the standard mechanical horsepower formula.

Purpose: It helps automotive engineers, mechanics, and enthusiasts determine engine power output from torque measurements.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( HP \) — Horsepower
• \( T \) — Torque (pound-feet)
• \( RPM \) — Revolutions per minute
• 5252 — Conversion constant (derived from the relationship between rotational speed and power)

Explanation: Horsepower is calculated by multiplying torque by RPM and dividing by the constant 5252, which comes from the relationship between rotational speed and power in the English system of units.

3. Importance of the 5252 Constant

Details: The number 5252 comes from (33,000 ft-lb/min)/(2π radians/revolution). This is why torque and horsepower curves always cross at 5252 RPM on dyno charts.

4. Using the Calculator

Tips: Enter torque in pound-feet and engine speed in RPM. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why is the constant 5252?
A: It's derived from the definition of horsepower (33,000 ft-lb/min) and the relationship between rotational speed and linear distance (2π radians per revolution).

Q2: What units should I use?
A: Torque must be in pound-feet (lb-ft) and RPM in revolutions per minute for this formula to work correctly.

Q3: Can I use this for electric motors?
A: Yes, the formula works for any rotating machinery where you can measure torque and RPM.

Q4: Why do HP and torque curves cross at 5252 RPM?
A: Because at 5252 RPM, the numerator (T×RPM) equals the denominator (5252), making HP equal to torque numerically.

Q5: How accurate is this calculation?
A: It's mathematically precise for steady-state conditions, but real-world engine performance may vary due to factors like friction and efficiency losses.