How much does air temp effect HP?

[MADMACS]

I am looking for some info or calculation for air inlet temp and how it impacts horse power.
My current air inlet temp is at 68, when are started data logging about a month or so ago I saw it as high as 124. I have not not logged it in the summy yet. But i am just wondering how much of HP differnece is between the to temps if any?
Thanks
Jim

 

[don_w]

There are a lot of other variables involved, but a general rule of thumb that has been around for years is every 10 degrees warmer is a 1% loss of power. So 60 degrees is about 6%. Keep in mind, this is a rule of thumb, not exact science.

 

[Dex]

Heat = detonation

Too much heat pulls timing which means loss in power.

 

[forensicsteve]

we datalogged car during a run couple of weeks ago. IATs were 250+ and timing was pulled to 9 degrees. Must have been a major drain on hp. Just installed alcohol injection system and having it dynotuned tomorrow. We might be as much as 1/2 second off with ETs, given we're at 20 lbs of boost.

 

[ChevyKiller]

The amount of power has a lot to do with it too. For example, if I'm on the dyno making 550 and the IAT's soar and timing gets pulled, the car will start to 'dip' in the 5600 range and level off after the dip and timing adjust.

Now, same car making 670 on the dyno and the IAT shoots up, and I've seen the car make a nose dive at 5800 rpm.

granted, every set-up is unique but I believe the amount of power greatly effects the amount of power drop from soaring IAT's.

One example just yesterday - I had made a half dozen dyno pulls and my resevoir water was very hot and I did another pull anyway. At around 5600-5700 rpm, my power dropped down about 50 hp instantly and steadily dipped down after through 6200. I tested a nitrous shot the very next pull without cooling down the water, and the car climbed all the way through 6200. It was specifically because the IAT's drove the power right out when it got too hot on the blower alone. The importance of keeping the IAT's cool is critical when making your power IMO.