does the a/c slow down a mc? does it take away a great deal of horsepower?

 

I can tell the difference when the A/C is on, but on an 'S', it's not "crippling" or anything. I'm sure some Cooper owners will chime in.

The modern rotary compressors are much more efficient than the "V"-type compressors from the early days of automotive air conditioning.

 

The more power you have, the less you'll notice the power loss of the A/C. The older MINIs don't have much low-end torque, so it is most noticable when you are starting off from a stop. I would expect a newer MINI, especially the 2011 with new engine management, to further reduce noticable drag.

 

06 MCS JCW GP with few mods feel like a stock MCS with A/C full blast.

 

Yes some power loss, but I'm guessing it's no more than 5%.

 

Not enough power loss to sweat my butt off. I always have the AC on. I rode one day home with it off and windows down and I was burning up when I got there. Yes there was more power, but IMO it isn't worth it.

 

On other brands of cars I have owned, the computer would temporarily turn 'off' the A/C compressor whenever it detected a need for HP (ie, you just stomped the gas pedal to the floor).

Does the MINI do that?

 

I think it does, the last 3 other vehicles I have owned do it. At WOT, the compressor kicks off and you get that blast of moist warm air. I thought this was mainly done on smaller engines with less HP, but my last 3 trucks (4, 6, and 8 cyl), and my wife's car (Mazda CX-7) all do it. I guess it is pretty normal.

 

I've got a MC Clubman and I notice a little bit of a drag tooling around town but not anything to serious. However, climbing steep grades (e.g., >5%) I can feel the difference when i reach over and turn of the AC.

I agree with above that it is mostly a fairly subtle drag at the low end.

I seem to recall a fairly extended discussion on BITOG of exactly how much HP loss AC accounts for but I can't seem to find it. Upshot is that at 120hp, you don't have lots of HP to burn so it will definitely be more noticeable on a Justa but at least for me, not enough to make me unhappy.