SAE J1349 • SAE J607 • DIN 70020 • JIS D1001
| Standard | CF |
|---|
The primary standard for North American dyno testing. Unlike the others, J1349 applies a mechanical efficiency correction (assumes 85% drivetrain efficiency) to account for engine friction losses, making it the most conservative — and most meaningful — CF for comparing engine output across different conditions.
Also known as STP or STD, SAE J607 is an older standard using a pure air density ratio. Due to this, J607 produces higher CF values than J1349 under identical conditions. Still encountered in older dyno software and historical records.
The German industrial standard, historically used by European manufacturers and in many European tuning communities. Uses the same higher reference pressure as JIS (1013 mb) but a cooler reference temperature of 20°C, which tends to produce slightly higher CFs than J1349 at warm temperatures.
The Japanese industrial standard used by Japanese OEMs and dyno operators. Shares the same 25°C reference temperature as SAE J1349, but references a higher standard pressure (1013 mb vs. 990 mb), which means JIS will produce slightly higher CF values than J1349 at typical altitudes and conditions.