Ambient temps and dyno figures
Thread Starter
Staging Lane
Joined: Mar 2009
Posts: 94
Likes: 0
From: Perth Australia
Ambient temps and dyno figures Hi Just wondering how much the ambient air would effect power numbers on a chassis dyno. I recently dynoed my car and the ambient air was hovering around 38c/ 100f mark on the runs. We we finding it hard get the heat out of the cell that day and these temps seem quite high to me personally. Intake temp recorded was only a degree below ambient. Pretty hot day to see those sorts of temps on the street. Made 627rwhp with my 408 gt4780 through a t400 and 9"
Most dynos have a weather cell and have options for several correction factors. SAE is what most people generally accept as the standard these days. SAE correction factor standardizes temperature to 77-degrees F, 29.23inHg and dry, 0-percent humid air.
Correction factors are designed for naturally aspirated engines there for are not accurate for a forced induction car. A FI car loses less HP compared to a N/A engine as you gain elevation. The higher the elevation the higher a FI's cars numbers read, since the correction factor is designed for the loss of power based on a N/A engine. Although not 100% accurate I think for a realistic number on a FI car take your uncorrected results + SAE corrected results and / 2. A FI car basically loses about half of what a N/A car would at altitude.
Correction factors are designed for naturally aspirated engines there for are not accurate for a forced induction car. A FI car loses less HP compared to a N/A engine as you gain elevation. The higher the elevation the higher a FI's cars numbers read, since the correction factor is designed for the loss of power based on a N/A engine. Although not 100% accurate I think for a realistic number on a FI car take your uncorrected results + SAE corrected results and / 2. A FI car basically loses about half of what a N/A car would at altitude.
Thread Starter
Staging Lane
Joined: Mar 2009
Posts: 94
Likes: 0
From: Perth Australia
ok thanks for the input, Also just noticed when i get off the dyno, on my eboost2 my peak boost is up 1 to 2 psi from what we were pulling on the dyno and it has happened twice now. Nothing changed at all. Thought maybe the high ambients in the cell could be effecting the power outputs.
