so now that its freezing in Chicago it seems as though my g has more pull than it did in warmer weather. Is this real effects or my imagination?

 

temp robs hp

 

Absolutely real...Cold air is denser than warm which makes a slug of cold air weigh more than if it was at a higher temp....More air mixed with fuel makes for a bigger bang in the combustion chambers..

 

Of course it's real. It's gotten much colder in NYC lately, and my car feels a lot quicker - to the point traction is minimal all throughout first gear and some of second.

 

I agree. My car pulls so much harder and smoother. It even for some reason goes into gear better to.

 

That's so strange how I just noticed this last night as well. 1st gear was also losing traction, which never happens in tucson because it's so damn hot.

 

actually, low temperatures rob hp only when the engine is not running at a proper temperature, this is why it's not very smart to run your car hard on a "cold" start.

however, very cool, dense air coming into the engine will improve horsepower because of the percentage change in volume of oxygen.

 

this could also be due to cold tires. Cold weather makes tires have bad traction.

 

Ding, ding, ding, we have a winner. Back in the day (1960's/1970's) a cheap way to get a bit of extra power was to stuff your air intakes with ice cubes. Don't know how well that worked only know that there were guys doing it.

We don't run our cars hard upon start up due to lubrication concerns as the oil is not warm at that point.

 

The 350Z has CARS (Cold Air Recognition System) that adds 20 horsepower in cold weather.

 

Just wondering if any of your responses are not sarcastic? They all seem to be.

Thanks to everyone else for their knowledge on the matter--for once there is a positive to living in an cold area

 

always love davidv's responses.

 

Probably 90 percent.

I can post 13.50 time slips from winter racing, and 13.90 time slips from July and August. Weather is a significant performance factor.

 

And if you could take your winter racing time and warm weather advantage on tire grip you'd get it down to 11.50 easily...

 

Indeed! Cold, dense (dry) air = better combustion.

That's why things like Cold Air Intakes (not necessarily "long ram" - but intakes that draw in cold air and has sealed of dissipated engine heat), and intercoolers for turbo and supercharges, and things like MotorDynes Coolant Control valve and Aramid gasket work...

Cold air is critical in racing... that's why you see colder climate states posting great 1/4-mile times! Some of them are running in 30-40 degree weather!

This Sat a bunch of us are going to the track (as long as it doesn’t rain) and temps are forecasted high 50s low 60s!!! That's awesome compared to 102 last time I went... and ETs will definitely show how beneficial cold, dense air is...

 

cold air = dense air = more power

more oxygen molecules in your cylinders means more fuel can be added, and more oxygen+fuel = more power

 

I think I read once that you can make as much as 2-3 % more power for every 10 degrees colder the temperature is.

So 90 degrees vs 40 degress could mean 10-15% more power. Definately noticable.

 

My car definitely pulls harder in colder weather. I even tested it, i used my head unit's G-force meter to see how many g's i can pull through second gear from 2k to redline. In hot weather like +80 degrees i could pull a maximum of .42-.43 g's with all different levels of gas in the tank. In cold weather like under 50 i can pull .47 g's consistently. I know its a pretty rough gauge, but i guess it works.

 

Air density increases 1% for every 11F temperature drop.....engine SAE rated with 77F inside plenum air temp.

High School Physics.

 

It makes a substantial difference.

I did a sequence of dyno testing measuring the effect of air inlet temperature Vs HP.

Several dyno tests were performed with inlet temperatures increasing from 50'F to 120'F at 10-15'F intervals. And several engine parameters changed as a result of inlet temperature.

1) The engine ran leaner at cold inlet temperatures and had substantially more upper midrange power.
2) The spark timing advanced as a result of cold air.

Conversely

3) The engine began to run very rich at high inlet temperatures and power went down quite a bit.
4) Spark timing was retarded as a result of the hot air.


When looking at the dyno curve, the difference between 50'F air and 90'F air made a difference very much like what the MREV2/spacer does on the dyno.

Peak power didn't change all that much, but there was a big increase in area under the curve from the cold air.

So yes, it makes a substantial difference. ~15HP in the upper midrange.
And I'm sure you are driving in air colder than 50'F.