Cold air to Hot air HP% equation ???

RMFheaders · Post by **RMFheaders** » Thu Aug 10, 2006 10:48 pm

Does anyone know the equation for HP % increase and decrease as intake temps change. I have seen it before but I can't remember what it is exactly.

MadBill · Post by **MadBill** » Thu Aug 10, 2006 11:09 pm

Theoretically, there is a gain of 1% power for ~every 5 F.° drop in intake temperature. Because the port and valve transfer more heat to a colder charge, the practical result is 1% gain per 8-10 F.° drop.
As far as the actual formula, density is inversely proportional to the absolute gas temperature, so for example, if you cool the charge from 140° F (600° R.) to 60° F. (520° R.) the density increases by 600/520 or 15%