i feel your pain. when i have 4 people in my lancer with the a/c on, my car is mad slow. but once everybody piles out and i turn off the compressor... no. wait. still slow.

 

That happens with most cars. When I had my ECU in my T'bird reflashed, I had it set up to turn off the ac compressor at anything over 1/2 throttle. 15% is a big loss with any amount of power. Adding 500+ pounds is hard on any et. Most guys pull out their back seat for the extra 30 at the strip.
BMan

 

Yeah, Shiv tested my Evo with the air on and it cost about 20 whp from what I remember.

 

The backseats do no weigh 30 lbs. They weigh at most 15 lbs. Anyway, the EVOs 5th gear sucks. You gotta downshift to 4th and turn the A/C off if you're going to try to run someone. Or you can go take him out through some turns. The EVO will blow the doors off 99% of DSMs through corners.

 

Wow that sucks, my evo definitely disengages the Compressor at WOT.. Many cars disengage the AC Compressor under load.. Do you think there's an ECU difference? I definitely can tell my AC disengages (it stops blowing cold air and the car wakes up) It seems to happen at about 80% throttle on my car. It is a tunable parameter on most cars that have the ability to have the ECU reprogrammed..

 

Even with the compressor disengaged, if you're still in an "A/C On" mode (ie. the little light is on, or your in Defrost or Defog modes), on most cars the engine ECU also reduces timing. So yeah, you get more performance at WOT since compressor disengages, but you're still losing power due to the timing shift. The compressor may only take 8-10HP to run... the rest is lost in the engine management adjusting for the load.

 

I would like to state that the Evo's 5th gear is overdrive...adding 600 lbs and having a the A/C on would even slow down a twin turbo porsche. The Evo's 5th gear sucks because it not geared for power...its geared to save gas.

 

you're still in 3rd grade.

 

my car definitely feels sluggish when i have the ac on.

 

Are you expecting to have the same performance w/ the AC on? One thing to check for is intake leaks. If you have any leaks in your IC pipes, it will really show in your off-boost AC performance. I remember when my EVO was new, I could barely tell the AC was on when driving around town.

 

You need to downshift!

AC should not disengage. If it does the calibrations on your ECU or PCM is either set inproperly or the battery voltage is low. If the ECU sense low battery voltage AC,heated seats, defrost, along with other things may shutoff.