[SYZ]

Originally Posted by regular guy

That would put your dyno correction factor at 4.61%, and your corrected horsepower around 517whp (assuming 494whp uncorrected is accurate).

Originally Posted by SYZ

You are arguing a 23whp correction to SAE on a 90 degree day at 5000 ft?

C'mon, you know better than that.

Originally Posted by img

Please check your math. 613 - 494 = 119whp. As the correction factor is stated as 1.24 (124%), you can do the math a different way from 494 * 1.24 = 613. So we're clearly talking about 119whp of correction and I'm not even sure where you got 23 from.

HP correction formula used by the dyno uses temperature, barometer, and humdity. Altitude is not in the equation.

see highlighted portion of where I got the number. I didn't realize altitude is not in the equation. Seem like it should be however, since SAE is supposed to be at sea level. Why have that as a standard if you don't compensate for it?

Edit: did a little research, amazing

Originally Posted by Shelquist Engineering

Additional Information:

Originally, all of the major US auto manufacturers were in or around Detroit Michigan, and the dyno reading taken in Detroit were considered to be the standard. However, as the auto industry spread both across the country and around the globe, the auto manufacturers needed a way to correlate the horsepower/torque data taken at those "non-standard" locations with the data taken at the "standard" location. Therefore, the SAE created J1349 in order to convert (or "correct") the dyno data taken in, for example, California or in Tokyo to be as if the data had been taken at standard conditions in Detroit.

For example, at 85 deg F, 24.71 in-Hg absolute pressure and 0.121 in-Hg vapor pressure, the engine only produces about 81.1% of the SAE rated power so that the required dyno correction factor is 1.233. Therefore, when dyno testing under these conditions, it is necessary to multiply the measured torque and horsepower values by the correction factor of 1.233 to determine the SAE corrected readings. The dyno correction factor takes into account all of the effects of temperature, altitude, atmospheric pressure and humidity to arrive at corrected horsepower and torque values.

The air temperature should ideally be the temperature of the air that is going into your engine.

The absolute pressure is the actual atmospheric pressure, also called station pressure. This is not the barometric pressure or altimeter setting as is typically reported on the local weather report.

The vapor pressure is the partial pressure of the water vapor in the air.

For these calculations, the standard reference conditions are: Air temp 77 deg F (25 deg C), 29.235 Inches- Hg (990 mb) altitude-corrected barometric pressure, 0 ft ( 0 m) altitude, 0% relative humidity.

http://wahiduddin.net/calc/calc_cf.htm