Enter the measured horsepower, temperature, barometric pressure, and relative humidity into the calculator to determine the corrected horsepower. This calculator helps to standardize horsepower measurements under different environmental conditions.

Dyno Correction Formula

The following formula is used to calculate the corrected horsepower:

CHP = HP * (1 + (T - 60) * 0.0003) * (29.92 / BP) * (1 - H * 0.0003)

Variables:

  • CHP is the corrected horsepower (HP)
  • HP is the horsepower measured on the dyno (HP)
  • T is the temperature at the time of the test (°F)
  • BP is the barometric pressure at the time of the test (inHg)
  • H is the relative humidity at the time of the test (%)

To calculate the corrected horsepower, multiply the measured horsepower by the correction factors for temperature, barometric pressure, and humidity.

What is Dyno Correction?

Dyno correction is the process of adjusting the horsepower measured by a dynamometer (dyno) to account for variations in atmospheric conditions. Since horsepower can be affected by temperature, air pressure, and humidity, dyno correction ensures that horsepower readings are comparable regardless of when or where they are taken. This is particularly important for comparing the performance of engines in different environments or ensuring consistency in racing regulations.

How to Calculate Corrected Horsepower?

The following steps outline how to calculate the Corrected Horsepower.

  1. First, determine the horsepower measured on the dyno (HP).
  2. Next, determine the temperature at the time of the test (T) in degrees Fahrenheit.
  3. Next, determine the barometric pressure at the time of the test (BP) in inches of mercury (inHg).
  4. Next, determine the relative humidity at the time of the test (H) in percent (%).
  5. Next, gather the formula from above = CHP = HP * (1 + (T – 60) * 0.0003) * (29.92 / BP) * (1 – H * 0.0003).
  6. Finally, calculate the Corrected Horsepower (CHP) in HP.
  7. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

horsepower measured on the dyno (HP) = 300 HP

temperature at the time of the test (T) = 75 °F

barometric pressure at the time of the test (BP) = 29.92 inHg

relative humidity at the time of the test (H) = 50%