1. What is the RPM Formula with Power?

Definition: This calculator determines engine speed (RPM) based on horsepower and torque values.

Purpose: It helps automotive engineers, mechanics, and enthusiasts understand the relationship between power, torque, and engine speed.

2. How Does the RPM Formula Work?

The calculator uses the formula:

Where:

• RPM — Revolutions per minute (engine speed)
• HP — Horsepower (power output)
• Torque — Rotational force (in pound-feet)
• 5252 — Constant derived from unit conversions

Explanation: The formula shows that RPM is directly proportional to horsepower and inversely proportional to torque.

3. Importance of RPM Calculation

Details: Understanding this relationship helps in engine tuning, performance analysis, and mechanical diagnostics.

4. Using the Calculator

Tips: Enter horsepower and torque values (both must be > 0). The constant 5252 comes from the conversion between rotational units and power units.

5. Frequently Asked Questions (FAQ)

Q1: Why is 5252 the magic number in this formula?
A: It's the RPM at which horsepower and torque values cross when plotted on the same graph (derived from unit conversions).

Q2: Does this formula work for electric motors?
A: Yes, it applies to any rotating machinery where you know both power and torque.

Q3: What if I only know kW instead of HP?
A: Convert kW to HP first (1 kW ≈ 1.341 HP) before using the formula.

Q4: Can I calculate torque if I know HP and RPM?
A: Yes, rearrange the formula: Torque = (HP × 5252) / RPM

Q5: Where does this relationship matter most?
A: In engine performance analysis, transmission design, and when comparing power curves.