How much horsepower does AC actually take?

[Run4two]

I too recall that AC was more efficient than windows down.

[Dtrimpi87]

Originally Posted by Nessal

Ummm...from my recollection, they found the opposite of what you are stating. They said that up to a certain speed, using the AC was much more efficient than the windows because of drag.

+1 AC was more efficient

Sent from the rocket in my pocket, my all powerful DROID BIONIC.

[Butcher]

I thought I was wrong once. It turned out that I was mistaken.

http://dsc.discovery.com/tv-shows/my...s-minimyth.htm

[amz]

When its hot outside , I mean really hot, I want A/C on.

Nobody wants to arrive at a destination , all hot and nasty , with a gallon of butt soup.

Give me A/C or give me death.

[Lee123]

Originally Posted by Butcher

I thought I was wrong once. It turned out that I was mistaken.

http://dsc.discovery.com/tv-shows/my...s-minimyth.htm

Interesting video. Thanks for posting it. Although I agree with their conclusion, I would have liked to see them repeat the test with the cars switched. There are a lot of things that could have made the dark car run out first in addition to the fact that the AC was on.

[IceRS]

Originally Posted by amz

When its hot outside , I mean really hot, I want A/C on.

Nobody wants to arrive at a destination , all hot and nasty , with a gallon of butt soup.

Give me A/C or give me death.

+1

[Butcher]

Originally Posted by Lee123

Interesting video. Thanks for posting it. Although I agree with their conclusion, I would have liked to see them repeat the test with the cars switched. There are a lot of things that could have made the dark car run out first in addition to the fact that the AC was on.

Like what?


They actually take that show very seriously. Most of the work they do is not on camera because it's boring. I would be willing to bet that they tested both trucks to make sure that they achieved similar mileage under similar conditions. Besides, it's not like it was close. The truck with the windows down went 15 laps farther than the truck with the AC on.

[Micawber]

I'd bet that it depends on the speed. At slow speeds the aerodynamic effect from the windows will be less. As the speed increases, doesn't aero drag go up by the square of speed? I'm guessing that the AC drag will remain relatively constant.

Edit: Those big SUVs aren't very aero so the window drag didn't hurt them as much relatively, either.

Also, as was mentioned, the outside air has to be cool enough to keep you comfortable. If it's too warm out, AC is the only way to stay cool.

[Kent2010]

Originally Posted by THE1chopper

<snip>

Having the AC on will MAYBE take 1-3hp to run

+1 on the 1-3 hp loss. You can "feel" it because unlike other sources of drag, it turns on and off in an instant instead of building up gradually.

Today's AC compressors are a LOT more efficient than those in the past.
And as has already been stated, WOT cuts off the compressor completely, so peak HP is never affected.

[blkevrythng]

Do they dyno tune with the ac on, cause everytime i jave gotten mu car back from a tuner, the ac is on max

[Butcher]

Originally Posted by Micawber

I'd bet that it depends on the speed. At slow speeds the aerodynamic effect from the windows will be less. As the speed increases, doesn't aero drag go up by the square of speed? I'm guessing that the AC drag will remain relatively constant.

Edit: Those big SUVs aren't very aero so the window drag didn't hurt them as much relatively, either.

Also, as was mentioned, the outside air has to be cool enough to keep you comfortable. If it's too warm out, AC is the only way to stay cool.

We're talking about the side windows. Most of the air is directed around the top of the car by the windshield. Think about it. If you're driving with the windows down at 65 mph. it isn't like you're sitting in a hurricane. Is it?

[Lee123]

Originally Posted by Butcher

Like what?


They actually take that show very seriously. Most of the work they do is not on camera because it's boring. I would be willing to bet that they tested both trucks to make sure that they achieved similar mileage under similar conditions. Besides, it's not like it was close. The truck with the windows down went 15 laps farther than the truck with the AC on.

You obviously know a lot more about the show than I do. I had never seen it and didn't know how serious they were. For those who've never watched it, the scene with the guy peeing behind the car didn't give the impression of a very serious show. There weren't a lot of facts presented, unless the video was edited down from the TV show. The video never said how much gas was put in the cars or how far they went (although he did say 15% which makes it sound like one of them drove 100 miles since the difference was 15 miles).

[mikeyroche]

Originally Posted by Parag

Driving with your windows down causes more drag than the ac being on. Mythbusters!

Who cares, your gas milage is affected much more by AC then your windows down. If you want performance, mileage and no overheating... just windows down. Its simple really. Yeah AC is great if its 30C and the humidity is max, but only if your sitting still.

[skipinminn]

LEATHER SEATS DON"T HELP EITHER for sweating your a** off .....LOL