I was just curious if anyone that owned a shop or had easy access to a dyno has tryed this. I was thinking at least a 10 horsepower loss

 

I am getting dynoed tommorrow and I will see if the tuner will compare runs.

 

I did, topspeed did so they said it would be under the most load.

 

^so what was the difference in HP between AC on and off?

 

I am pretty sure that during a WOT pull the ECU cuts the compressor off.

 

I think that is how you are suppose to dyno tune a car. That way the car can get tuned at idle with out issues

 

wow thats pretty cool, i think ill use it more now when driving fast

 

I remember hearing from someone that they left the A/C on during the tune, and the tuner was puzzled to see that the car wasnt making the power it should be making. Then they realized the A/C was on, turned off the A/C, and did another pull and the hp numbers were up to par with the mods the car had. Dunno the exact HP difference though.

 

Didnt do a before and after pull. First pull was made with the ac on.

 

personally i wouldn't do that.

i don't know if the a/c compressor wheel/system would be happy to rev upwards 7000rpm.

when i use the a/c i try not to rev past 4500rpm which is plenty for road use.

Plus to have your a/c on, it means that it is HOT outside so why abuse the car under the hot weather...

 

the ecu turns the compressor off for you when you hit wot

 

i dont think thats right. ive got on it and noticed the power loss and realized the ac was on....

 

It actually does turn off the compressor. Most cars will do so to give you more power when you hammer it. We also have a 2005 VW Bug and when you smash the gas you will notice the AC compressor turns off and warmer humid air starts to blow out. Come to think of it, my brother has an old bunk 1999 saturn and when you mash it, it does the same thing.

I have an AEM ECU in my evo and it does the same thing. I'm sure you could turn that feature off if you wanted too.

 

This is a feature available with the AEM, but I don't think the OEM ecu shuts off the a/c @ wot. At least not for the viii's.

 

wow, i learned another new bit of info today. thx!