I was just thinking how bad does having your air conditioning on effect your times or performance?

 

It slows my truck down about .5 seconds

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Follow my racing progress on Stephen's racing page
and check out the race car

87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block (times are for the current engine)

Best ET on a time slip: 11.447 altitude corrected to 10.99
Best MPH on a time slip: 119.42 altitude corrected to 124.86
Altitude corrected rear wheel HP: 493
Best 60 foot: 1.586

Racing at 3500 feet elevation with a typical race day over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

 

I turn mine on before some of my autocross runs... I've been told that it advances the timing a little. I have no idea if it helps or not.

 

I don't know about the advancing timing but it will increase your idle speed a hair (that's in the eprom I know!).
You need to understand that a/c isn't always ON so to speak. The compressor doesn't just stay engaged, it has a clutch and whenever the pressure falls below a certain level it turns back on. When it goes on you loose lots of power. It's like trying to run a small air compressor. Ever watch those portable air compressors and how hard those engines need to work just to compress the air, same deal.

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, Jon (350 TBI!)
91 Red My website

 

Anything that puts a load on your engine will rob horsepower, not to mention with the A/C on you'll be dripping condensation onto the track.

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1989 Mustang LX 5.0 Coupe
13.34@106.7 - needs more gear and converter

1992 Mustang LX 5.0 Convertible
14.23 @ 95.something - 100% bone stock motor - it's been a while since I've ran this one

1993 LX 2.3L Hatchback - "The Ride to VCU"

Moderator Stangtec.com, SN95.com
Amelia and Nic's Twin Terrors

 

yeah I was just wondering about how bad it slows u down. I mean I have mine on and I can tell the performance difference I was just wondering how bad it is on times. Its weird on mine. It never turns off unless turn it off. The compressor that is.

 

Stuff like that tends to get you kicked out.

 

These are my actual times in the 1/8th mile. These runs were right after each other, no adjustments were made in between.
With A/C off:
Reaction - .6067
60 ft. ET - 2.2693
330 ft ET - 6.3329
660 ft ET - 9.6816
660 ft MPH- 73.63
With A/C on:
Reaction - .5773
60 ft. ET - 2.3395
330 ft ET - 6.5186
660 ft ET - 9.9506
660 ft MPH- 72.10

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1988 Camaro Sport Coupe: Orignally: 305 TBI 700r4
Now: 1974 355CI, 2bolt, Badger Flat Head Pistons w/ valve relief, Melling high performance street cam, GM Cast Vortec Heads, Edelbrock RPM Air Gap Intake, Edelbrock 600cfm w/ electric choke, GM HEI w/ vacuum advance, Weiand Low Profile Air Cleaner, Mallory 5 port Fuel Pressure Regulator, Mr. Gasket Throttle Cable Bracket, Corvette Shift Servo, 16" IROC Wheels, Every thing else is STOCK
Soon: 3.73 or 3.42, Gears, Hoosier Q/T

 

well thats not a big difference, but on my car I can feel it it. Maybe my compressor is about to lock up or something. The back of my AC has a bunch of oil substance on it.

 

That may not seem to much to you but sure is a bunch to me. Believe me, I notice a difference when it is on.

 

I thought our cars had an a/c overide switch or something like that that cut the compressor off at wot. I could be wrong.

 

newer sports cars do, I'm not sure about ours.

 

There are settings in the eprom (SD and 1989 MAF for sure) that you can adjust the %TPS that kicks out the A/C. There are also "delays" so you can adjust to make it kick out instantly once the %TPS threshold is reached.

Properly adjusted, the A/C shouldn't penalize you any differently whether it is on or off. However, you still have the "drag" issue of the compressor itself. But you can make the car perform the same if the A/C is on or off with proper adjustments to the eprom.