MATH in DYNO-TEST

1. Calculation of Torque

Torque is the rotational force measured by the dyno load cell.

Formula: Torque (lb-ft) = Force (lb) × Distance (ft)

2. Calculation of Horsepower

Using the torque value and engine speed, you can calculate the horsepower.

Formula: Horsepower (hp) = (Torque × RPM) / 5252

3. Metric Conversion

If you are using Newton-meters (Nm) and Kilowatts (kW):

Formula: Power (kW) = (Torque in Nm × RPM) / 9549

Quick Reference Table

Metric	Value/Constant
Imperial Constant	5252
Metric Constant	9549
Intersection Point	5252 RPM

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The Physics of Torque Calculation

Torque is the measurement of rotational leverage. In a dyno test, it is calculated as the product of the force exerted at a specific distance from the center of rotation.

The Basic Torque Formula:

Torque = Force × Radius × sin(Angle)

• Torque: Measured in pound-feet (lb-ft) or Newton-meters (Nm).
• Force: The physical load applied to the dyno sensor (lb or N).
• Radius: The length of the moment arm (the distance from the crankshaft center to the sensor).
• Angle: In a controlled dyno test, this is 90 degrees, making sin(90) = 1.

Why the 5252 Constant?

The relationship between torque and horsepower is bridged by the definition of mechanical work. Power is work divided by time.

Step-by-step Derivation:

1. Horsepower = (Torque × RPM × 2 × Pi) / 33,000

2. Simplifying the conversion (2 × Pi / 33,000) results in the constant 5252.

Final Formula: Horsepower = (Torque × RPM) / 5252

Data Analysis Tip

When auditing your dyno logs, remember:

• Torque is your independent variable (measured directly by the sensor).
• Horsepower is your dependent variable (calculated mathematically from the torque).

Note: Always verify your "Radius" (the brake arm length) is precise, as any error here will propagate through all your torque and horsepower calculations.