FREE TOOL · DYNO STANDARDS
Dyno correction factor (SAE / DIN / EEC)
Correct observed dyno power for atmospheric conditions. Without correction, the same engine reads 5-10% different on a cold winter morning vs a hot summer afternoon. Standards: SAE J1349, DIN 70020, EEC 80/1269.
How the correction works
SAE J1349: Reference 25 °C dry-air pressure 99.0 kPa (990 mbar). Correction factor cf = (990 / dryPa) × √((Ta+273) / 298).
DIN 70020: Reference 20 °C and 1013.25 mbar dry. Used by most European OEMs in marketing horsepower figures.
Humidity reduces dry air partial pressure — at 50% RH and 25 °C, water vapour partial pressure is ~16 mbar, so dry-air pressure is observed barometric minus 16 mbar.