myfast70

iTrader: (38)

We had a dyno day this past weekend and I heard something interesting and wanted to see what everyone thought. I was told that for every degree of temp drop that you can expect 1-1.25 additional hp for N/A applications and 1.25-1.5 additional hp for F/I. How true is this? So my car put down 390rwhp in 96 degree weather which would mean that it would be putting down 420rwhp in 65 degree weather. Is this possible?

WeathermanShawn

iTrader: (1)

I've used the Engine Tuner's Calculator found on this website: http://wahiduddin.net/calc/calc_hp_dp.htm.

You can play around with temp, humidity, altitude etc..

General rule of thumb is a ~1% change in HP per every 10 degrees.

PHX is 1290 feet..I'm coming up with a 3.2% change, using your 96f, and 65f temp (assuming humidity, pressure the same).

There are some interesting articles on that website. Thats my understanding of the process. Hope that helps..WeathermanShawn..

cantdrv65

iTrader: (3)

For uncorrected numbers yes....but for corrected SAE numbers theoretically the difference should be zero. Of course the coorection isn't perfect so you will see some small changes but don't expect much....

Sigforty

Exactly what I was going to say. If the Dyno showes the CF (correction factor) as SAE then there should be no difference.

GuitsBoy

iTrader: (4)

unless of course youre pinging in the hot weather, in which case youll have better results when its cooler and your motor is not pulling timing. Aside from that the correction factor is pretty good at what it does.

ringram

The ECM will also pull timing even if its not pinging when IAT temp hits certain values usually over around ~28*C (Dont ask me what that is in ancient legacy *F)
Mainly because if spark isnt reduced it will ping due to hotter charge temps.
Thats why a 160* thermo is good as it helps keep heads etc cooler to reduce charge temp transfer.

utryd2

iTrader: (2)

Good info. Had the same question.

edcmat-l1

iTrader: (10)

Even with the CF set to SAE, an engine, or vehicle will make more power in cooler temps. We proved that yesterday and the day before, when we had a car pull 494 in about 100 degrees plus, and 503 the next morning, with the temps about 89 degrees. This was with no timing being pulled due to IATs on either day. When we turned the IAT/timing table back on, we lost a **** load of power. Like almost 20 HP.
CF (correction factor) is just that. A computed factor/equation. It's not perfect, and cant really account for how much a certain motor may enjoy the added oxygen.