Driving our 6MT with the a/c on vs. with the a/c off?!?! It's like driving two different cars. It's harder to drive and shift smoothly with the a/c on and the shift points are definitely different. Anyone else feel like this?!?

 

Pretty sure that most cars are like this. It takes a lot to power the a/c and I would guess you lose 5-10% of your power. I definitely lost some races in my mustang and realized I had the a/c on.

 

I have noticed this in all the cars that I have driven. I think like ~30% of your power is cut b/c of the a/c.

 

lmfao no way 30%...someone did a dyno with ac on and off and it was around 8hp loss for an 8th gen accord v6 6 speed.

 

it wasn't the a/c's fault. Lol

 

Agreed!! It's only about 5-10 hp loss. It takes a few horsepower to turn the a/c compressor but 30% is not a feasible number.

 

vill1069 removed his AC for his track car!
I bet that thing PULLS!

 

Drive with your windows down and roof open. Problem solved.

 

I think I remember reading that the a/c compressor draws about 8-15hp depending on the size of car and strength of the a/c. The TL is a little weak on low end power so it will be especially noticeable. Most cars have a switch that disengages the a/c compressor when at WOT (wide open throttle) so it shouldn't have any affect when you've got it floored.

 

not really, its probably as bad as the AC. you've just increased the drag your car is producing so it will require more power to overcome it. just drive only during the winter. you can turn off the AC and maintain the aerodynamics of the car by keeping the windows closed.

if its really that much of an issue...just add all the performance bolt ons to your car to make up for the losses due to the AC being on.

 

Interesting. For some reason, I thought I read somewhere that the opposite was true i.e. driving with all your windows down is not good for drag coefficient or something along those lines.

 

lol I used the "~" b/c I didn't know the exact % with 30 being the greatest. There is a noticeable difference and it becomes more apparent in lower torque engines.

 

That is absolutely correct. The increased drag will decrease the efficiency more than the AC compressor will. The faster you are going, the more this is true.

The truly ELITE run with no AC and the windows up all summer. It's a small price to pay for a 2% increase in MPG and 5 extra HP.

 

True. Mythbusters did a show on this.

 

uhhhh in my 04 auto i feel like its going faster.....hmmm interesting!!

 

aerodynamics might slow the car but it has no affect on the engine speed between shifts.

I too feel that the A/C does noticeably affect RPM drop between shifting. It happens to pretty much every car though.

 

true, but your car would turn into a parachute of sorts with all the windows open even the engine may "feel better."

wonder why cyclists wear all that tight fitting lycra?? engine is the same on the bike (rider), but now you still have to overcome the drag forces if you put a big baggy jacket on and ride. so speed will be affected for the same given distance. so its not efficient or you have to increase your power output for the same given effort.

in real world driving, does it really even matter??? driving in a metro area you can't get your car to go fast enough to utilize the HP loss from the AC anyway.

 

I thought I was the only one that noticed this..I must say it isn't bad compared to my 2000 honda accord I had.

 

Best of both worlds as one needs to drive with windows and sunroof closed and A/C off.

 

+1!

So true. This always bugged me about my TL, since my wife's G35 is so friggin torquey, using the a/c is barely noticeable on her car.

Then I got my cylinder heads ported on my TL. At first I didn't think the gain was that noticeable, but I realize now that the improvement is definitely noticeable... and the a/c impact is still there, but MUCH LESS. (I am aware that most of the gains from the porting will be at the top end, but somehow it still helped a lot).

Of course, having the cylinder heads ported is damn expensive. I had bent my valves so it was just a minimal up-charge for me, considering the work I was already having done. history on that here in this thread

 

all cars will lose power with the ac on. it's worse in a turbo/supercharger car.

 

Its actually worse in gas milage/HP when the windows are open than AC because of the drag on the car.

 

I've heard the same, apparently windows and sunroof opened is = windows closed, a/c on

 

In the older days it was more efficient to run with the windows down but in the past decade or two A/C units have become much more efficient so better HW mileage with the A/C on and windows closed. City driving is the opposite however.

 

some people feel that the impact of AC is really bad on performance but its mostly psychological. yes it probably loses 5-10hp but its mostly because the throttle doesnt feel as responsive, that adds to the feeling of losing more power

 

Indeed that is true, city driving with lots of stop and go is where the ole A/C on is less efficient than the windows down.

 

Learn something new everyday.

 

No one mentioned it yet, but we aren't using 200+ horsepower when we're driving a TL on the freeway or street.
The car probably uses 40 HP or less to drive & maintain freeway speeds-- I've seen figures between 25 HP and 40 HP for other cars. If the A/C is taking 8 HP and the TL is using 25 HP @ 35 MPH on Main Street somewhere, then the A/C could be taking up to 30% of the HP being generated by the TL to maintain that speed.

I'm not sure about the exact HP/speed figures-- a dyno run @ 1400 RPM-1800 RPM would show the approximate HP range generated at street & freeway speeds; compare that to the AC's 8 HP drag...