sccsiouxland

Like the title says this is kind of useless but I am curious.

The other night when it was supposedly 10 or 15 below zero I was in the Focus and whenever I gave the throttle a little massage there was more torque than in warm air like night and day....it almost seemed as if I had a usable amount of power My question is if there's any way to know how, or at least get a guestimation of, much more power you get in the cold.

Tony, I read somewhere that an 11 degree drop in temp at the intake is good for about 1% more power. Cooler air is denser air, which makes more power. So you are correct in thinking that the car was making more power.

Damn my butt dyno's good!

Haha when I was givin it hell it seemed closer to the power my brother's car makes than the power mine makes...~130 whp, compared to my ~115 whp.

Assuming the dyno for that 115whp was at 80 degrees (was taken at focussport in california), and it was -11 on monday night (weather.com says so it's the law) I should have been at about 125 whp if that 11 degrees to 1% hp is right.

http://users.wpi.edu/~ierardi/PDF/air_density_plot.PDF

http://www.cowtownmopars.com/airdensity.html

The first link is a plot showing the inverse relationship between air density and temperature. As the temperature of any gas decreases its density increases. As was mentioned above...air that is more dense has a greater capacity for more power. (More air can burn more fuel in the same amount of space...providing more power).

The second link I didn't play around with much but it is some type of density calculator that accounts for variables like temperature, altitude, and humidity. Looked kind of interesting.

The density of air being combusted is the reason that turbocharged vehicles have intercoolers to cool the pressurized air entering the throttle body. If you drive a turbocharged car you will notice a profound difference between 40 and 80 degrees F.

Naw the focus doesn't have a turbo.......yet

I knew why it was happening I just wasn't sure how big the numbers were.

At the autox events in the summer, my car really feels like a dog in terms of straight line acceleration compared to the winter months (boost levels being adjusted to the same psi reading).

The evo is a whole different beast in the winter. Out of curiosity, I've data-logged a 20+ whp difference between the summer and winter months on my mildly modified evo. The butt-dyno can verify that too!