sae gross vs sae net

[Mark Niksic]

Does anyone know if ther is a linear comparison or formula to transfer between the old gross hp ratings and the new net ratings. I am trying to determine the real rated difference between my 1969 300 hp vette and my wifes 1979 L82 vette rated at 225hp. Both are 4 spd cars. Thanks in advance, Mark.

[Ed Jennings]

Re: sae gross vs sae net

There is no linear relationship, since different engines are affected differently by the change in testing methods. However, as a general rule you can take about 30% off the gross and be somewhere in the ball park of the net. This conversion factor is relevant to larger V8's and may be way off for smaller engines. As an example, a 71 LS5 was rated at 365 gross HP. The 72 LS5 was 270 net HP. The 71 LT1 was 330 gross HP and the 72 LT1 was 255 net. Given this relationship, the 327/300 and the L82 aren't too much different though the 350 may have a bit more torque due to the longer stroke.

[Mark Niksic]

Re: sae gross vs sae net

Thanks Ed, I appreciate the help.