Hey everyone. And fellow RS4 owners! I'm at 9,500 miles on my 07 RS4, and it runs like butter.

I know that having your heat or AC on detracts power from the engine. If I have it on say 2 or 3 small bars, how much slower is it making my car? Is there an actual performance difference? I reach 60 normally in 4.5-4.6 seconds on my tests, will this decrease that time?

Thanks guys!

 

With most cars (performance or otherwise) the A/C pump is cycled OFF at full throttle. For part throttle application, the A/C pump will still be on while you're accelerating, but since the pump is only drawing 5-10 HP, its affect on your acceleration is small. BTW, the controls on your dash affect the fan speed for your A/C or heat, they don'y affect how much power the A/C pump is demanding from the engine. So in general, having the A/C on at highway speeds has more of an effect on power available at your wheels (and gas mileage) than at full-throttle.
tim

 

Thanks Tim. I have economy on for the AC, meaning it's getting the air from the outside. Does this still take the 5-10 horsepower?

 

No....economy turn off the A/C compressor.....I believe? I turn it off in my RS4 in the winter time, though it's hard to tell any difference with it off or on, as the car has such a great power band.

PW