That Guy 1987

What's going on guys? Went to get my car retuned and wasn't to thrilled with the numbers granted i know we all say the dyno is a tool. Now I made 439 at 13 psi late November last year about 50 degrees outside. Went back today and made 400. It was about 85 outside here in FL. Question I have is does or will heat affect horsepower this drastically? I read for every 5 to degrees 10 dropped you make 1 percent more horsepower. Tuner always mentions that his dyno dynamics reads low next to a dyno jet.

baZurk

Were you on two different dynos? Heat as well as humidity can rob a lot of power of a FI car

That Guy 1987

No, same tuner and same dyno.

JJAUTOWERKS

Jesus!

KaNgArOo

That sucks. But 50 degree compare to 85 degree is a big difference. I'm also going to assume humidity was up as well. So yeah, i would blame the heat/humidity.

KaNgArOo

How was your Boost pressure? Was is still reading at 13psi?

CoolGuy094

My question as well. I would expect a PSI loss at higher ambient temp and humidity, which would lead to the power loss.

Forcedbird

Compression test??

yamahaSHO

Boost pressure should not change.

Not only will heated air make less power, but various ECU temperature compensations could be in play by removing timing or adding fuel. Ideally, a correction factor takes care of the former, where the latter would need to be handled by the tuner.

CoolGuy094

Whoops, I guess I was thinking of a SC setup where boost is determined by pulley size, not by wastegate, controller, etc.