Temperature vs. MPG ?

[whitevette]

Rather than get tangled in the many parameters which affect fuel consumption (previous posts go into everything from tire pressure to engine management "tricks"), let me throw one more over-looked idea into the brew.
Everyone is aware of lower air temperature causing gas mileage to sag.
One just doesn't get the same gas mileage in the winter as in the summer months; it is noticeably less. Blame has been placed on everything imaginable.
Cold air is more dense than warm air. But why must this density increase (or temperature decrease) create such a drastic change? I'll propose a simple argument: It's impacting more molecules (of air) as the vehicle is driven through the air. This higher viscosity air must be "forced apart" by the front of the vehicle with an increase in throttle ... thereby requiring a bit more throttle.
I can hear the cries now: "Absurd!" "Crazy"! ...let me offer the following reason.
Any pilot will tell you airplanes develop less lift when the surrounding air is hot. Summer weather calls for a longer take-off roll (or landing length of runway) than cooler weather ... or, higher altitude airfields (where the air is thinner) need longer runways than lower elevation airfields. These are very drastic differences. Doesn't the same air affect cars & trucks?
Remember the K.I.S.S. principle....

[gone-ot]

DENSE air = cold, low-humidity

LIGHT air = hot, high-humidity

[user removed]

From freezing to 200 degrees F air density decreases about 25%.

I think it decreases close to 50% from seal level to 18,000 feet.

Didn't look it up to be more precise but that should be fairly close.

regards
Mech

[aerohead]

Originally Posted by whitevette

Rather than get tangled in the many parameters which affect fuel consumption (previous posts go into everything from tire pressure to engine management "tricks"), let me throw one more over-looked idea into the brew.
Everyone is aware of lower air temperature causing gas mileage to sag.
One just doesn't get the same gas mileage in the winter as in the summer months; it is noticeably less. Blame has been placed on everything imaginable.
Cold air is more dense than warm air. But why must this density increase (or temperature decrease) create such a drastic change? I'll propose a simple argument: It's impacting more molecules (of air) as the vehicle is driven through the air. This higher viscosity air must be "forced apart" by the front of the vehicle with an increase in throttle ... thereby requiring a bit more throttle.
I can hear the cries now: "Absurd!" "Crazy"! ...let me offer the following reason.
Any pilot will tell you airplanes develop less lift when the surrounding air is hot. Summer weather calls for a longer take-off roll (or landing length of runway) than cooler weather ... or, higher altitude airfields (where the air is thinner) need longer runways than lower elevation airfields. These are very drastic differences. Doesn't the same air affect cars & trucks?
Remember the K.I.S.S. principle....

whitevette,check this table out

[Lazarus]

Here's a few more ideas on the mix.

Here's a density altitude chart.

[whitevette]

Originally Posted by aerohead

whitevette,check this table out

Be more than happy to ... what table?

[aerohead]

Originally Posted by aerohead

whitevette,check this table out

the search title is in the header of reply.

[saddlsor]

I took a 6 week trip that started in indiana, went through the southwest and then up the west coast. I kept pretty close track of my mileage and something I noticed was when I was in the hot air down south my mileage increased by quite a bit. I was getting my normal 23-24 until I got into texas and at the time the temp was a 100+ every day. I noticed my mpg was going up and it stayed the same until I got to california where the temps started getting a bit more normal. I drove a couple thousand miles over a 2 week period where the temps were over a 100 every day( but it was a dry heat the average for my tanks during that time went to 28-29mpg, which is the best its ever done. the only thing I can attribute it to was the hot temps as nothing else changed. it would be nice if I could do that good all the time.

[MadisonMPG]

Originally Posted by saddlsor

I took a 6 week trip that started in indiana

You can, it's called a (WAI) warm air intake.

[saddlsor]

Originally Posted by MadisonMPG

You can, it's called a (WAI) warm air intake.

I tried that and haven't done enough testing to see if it makes a difference but I can tell just by the miles I'm getting on a tank that it's not going to be the same thing. the increased mileage I got on this trip in the southern states and warm air is what got me to thinking about a wai. I know some on here have had good results and some haven't so thought I'd try it myself.