Quote Originally Posted by Vteckidd View Post
it doesnt ALWAYS change, but i have seen it change before. A lot of that comes down to just trying to find an extra 5whp and its almost impossible to get the exact number again and again back to back on a dyno. Like mosely said theres too many other factors. So at 30psi your engine oil was 5 degrees warmer than at 50psi, or your IATs were 5 degrees off, etc. Too many factors.

Youre also not MOVING a dyno drum, your spinning it, so it has some sort of built in mass inertia calculation(moment of inertia something like that) that it uses to calculate hp instead of the normal way.
I have not seen an issue of tire pressure affecting a dyno output, but I do know that Dynapaks readings are direct - and remove the tire from the equation. Matt (the HITman) recommended Dynopaks to me, as he believes that the tire can affect readings. His opinion definitely trumps mine.