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Does AC slow down the car?


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When you go into Open Loop (wide open throttle, or thereabouts), the compressor turns off and stops leeching horsepower. Otherwise, yes, it does leech a little bit of horsepower.

 

And yeah, the turbo cars will lose horsepower due to heat. Not terrible, but it will lose some. For me, I get a noticeable boost in power in the winter months.

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Yes it does. The accessory pulley goes under more strain, which is ran off of the belts coming off of the crank pulley, that means that less power is actually getting to the wheels. The is a general statement, and it may be slightly different in some vehicles. But i believe the result is always the same.
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When you go into Open Loop (wide open throttle, or thereabouts), the compressor turns off and stops leeching horsepower. Otherwise, yes, it does leech a little bit of horsepower.

 

I agree - no power lost. At greater than 70% throttle, running the AC has no impact on power due to the compresser being shut off. At less than 70% throttle, the compressor does take some power to run.

My '05 LGT

My '07 Supercharged Shelby

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Legacy GT's have decent low end power, enough to not really notice the power loss from the A/C compressor going while it's on, infact when you have the A/C on the compressor cycles in and out, so it's not always engaged only around half the time. In previous cars that I've had the A/C would kill the power, manly because they didn't have much to give up in the first place, and I needed to drive with the A/C shut off in order to drive agressively, but with the Legacy GT it's no problem.
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Gee, two threads on the same topic, with various points of confusion.

 

Engine intake temperatures (which some people here interpreted the "heat" question to refer to) do affect performance. Running the car's heater really doesn't in any significant way (and, as noted in the other thread may actually improve it sometimes).

 

The air conditioning pump (the compressor) does indeed take power to run, so when it's running there's less power to the wheels. This is most evident in NA cars.

 

However, it's generally the case that your mpg will be better with the AC running than with the windows open, due to the aerodynamics. HPH

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Gee, two threads on the same topic, with various points of confusion.

 

Funny you said that, I checked the other post thinking it was the one I posted on and my reply wasn't there so I had to think hard if I actually posted it, lol. Funny how both threads have the same exact name as well.

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Yes, as said above, anything that runs off the crankshaft takes away HP

 

IMO the change in MPG and HP with A/C are so minor it's not worth talking about.

 

Now if you leave your HVAC in auto and drive with the windows open, now that's just stupid.

 

Drove to VT yesterday morning windows up, no A/C got almost 27mpg. Drove home with the windows open, total mpg ended up at 27.9 on the dash computer. Yea I know it lie's.

 

If I fill up in VT and drive home I've gotten over 28mpg last ski season.

 

I only use the A/C when I have to and hate the auto setting.

 

Seems I can get 26-27mpg with the A/C on also on the VT loop, it's about 300 miles. Trying to remember...

 

I know I have slowed my speed down the past year or so, cruise control at 65-68 makes a big difference. I think that's a bigger factor the having the A/C on/off.

 

It's only 10mph slower but I gain 2-3 mpg.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

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If you are concerned about the mpg, better to leave your windows shut with A/C ON.

So says Mercedes.....

Less Drag with the wind and I think LGT has enough Low End Torque to not even notice that much difference.

I do feel that the RPM drops faster but that's something you can get use to.

As people have stated, If you are doing WOT, the compressor should turn off.

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