How much horsepower does AC actually take?

[Lee123]

Now that it has heated up enough that I'm driving with the AC on a lot, I've noticed that I can really feel the difference in performance when it is on. More difference than I would expect with over 400 HP at the rear wheels. My wife has complained about this with her Focus ZX3 and that doesn't surprise me. I would think the compressor would take about the same amount of HP in every car and if that's 20 HP that would be 15% on my wife's car but only about 4or 5% on mine. I wouldn't expect to feel that much.

Does anyone know how much power the AC actually consumes?

[10forty2]

Not sure of the exact answer for your question, but for clarification, you don't have 400+HP at the rear wheels (unless you are significantly modified)...you've got that at the flywheel, but not to the ground.

[Pay2Play]

Originally Posted by 10forty2

Not sure of the exact answer for your question, but for clarification, you don't have 400+HP at the rear wheels (unless you are significantly modified)...you've got that at the flywheel, but not to the ground.

Check his signature. His car is cammed.

[2010ABM]

It's not so much just what the AC sucks down, but more of what the heat is doing to the car. The motor is getting heat soaked now that it's hot...just part of having a V8 and hot temps. The difference will most certainly be noticeable.

Putting down over 400RWHP on good cool air is a completely different story than 400RWHP on a 100+degree day.

[Rcfiddy1]

The a/c will heat up your engine, also when you go WOT the a/c kicks off. If your worried about the car overheating try and shut off a/c in traffic or try to maximize your air flow thru radiator and out of engine compartment.

[Lee123]

Not worried about it overheating. Even after running it fairly hard when it is 105 out the gauges show no sign of overheating. It just feels a bit more sluggish on part throttle acceleration when the AC is on compared to when it is off. I have excessive curiosity about this kind of thing and was just wondering how much power the AC really takes.

The car put down 426 HP on a Dyno Dynamics dyno that is known to be a bit on the stingy side. That was in March so it wasn't that hot out. A nice day, though. About 80 outside and a bit warmer in the shop.

[amz]

Probably about 10 hp.

[10forty2]

Originally Posted by Pay2Play

Check his signature. His car is cammed.

Didn't read the fine print, (but I did say unless it was modified..) LOL!

My guess would be the AC drags down about 10-15 HP. Not positive about it, but I think it's more of a friction thing rather than heat generated by the AC. The compressor takes power to turn and the only source is the engine. So when it kicks on, it steals power from the engine and consequently from the rear wheels which is then felt in the seat of your pants!

[daveagogo1]

Heat is your worst enemy. Here in Florida mine runs like a pig all summer long then wakes back up when temps cool off. Very noticeable. Summer blend gas doesn't help either.

[jmaynard]

Ac takes a considerable toll on the performance (thats why NASCAR cars are not equiped with it). To get a good idea, at idle with turn on the ac (w/ compressor) and you will see the momentary pull on RPM's . The negine will sense and auto rev up, but that lull is your prformance dip. I would say a 5-10% number would be close.

[THE1chopper]

Originally Posted by 2010ABM

It's not so much just what the AC sucks down, but more of what the heat is doing to the car. The motor is getting heat soaked now that it's hot...just part of having a V8 and hot temps. The difference will most certainly be noticeable.

Putting down over 400RWHP on good cool air is a completely different story than 400RWHP on a 100+degree day.

^^^ right on...

to make it simple...think of 2 imaginary boxes of air molecules, one is 100 degrees and another say is 50 degrees. The box that is 100 degrees doesnt have NEARLY the amount of air molecules ( things that make your engine very happy) as the 50 degree one...

So not only is cold temps better bet ALSO high pressure!

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

[Parag]

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

Also you dont have a constant 400 hp running. Cruising you are only using about 20 hp. So if my ac unit takes ten, we may have a problem.

The 70 lbs of the system probably costs
More than the drag.

And really, had to throw a nascar reference in here. Lol. Cause if it wasnt for the drag on engine they would totally have ac units. Lmao

[Butcher]

Originally Posted by Parag

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

Also you dont have a constant 400 hp running. Cruising you are only using about 20 hp. So if my ac unit takes ten, we may have a problem.

The 70 lbs of the system probably costs
More than the drag.

And really, had to throw a nascar reference in here. Lol. Cause if it wasnt for the drag on engine they would totally have ac units. Lmao

You might want to watch Mythbusters again, because you are completely wrong. Driving with the windows down was FAR more efficient than using air conditioning. Using the AC burns more fuel, puts more load on the motor, and causes the motor to run hotter. Not to mention, if it's hot enough outside to use the AC, then the air is already causing you to lose some horsepower.

[Nessal]

Originally Posted by Butcher

You might want to watch Mythbusters again, because you are completely wrong. Driving with the windows down was FAR more efficient than using air conditioning. Using the AC burns more fuel, puts more load on the motor, and causes the motor to run hotter. Not to mention, if it's hot enough outside to use the AC, then the air is already causing you to lose some horsepower.

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.