[bird72]

This may be a "I need a life question", wait, yes it is.

Has any of the car rags in days of old tested an A/C musclecar and ran without air runs and with air conditioning on runs? Better yet, anyone here? Someone must have done this. Why I need to know is subject of probable therapy justification. Mostly curious of actual performance impact of A/C.

[71GP76TA]

FWIW - I hit 115mph in the SD with the A/C on... and it was still pulling..

[njsteve]

It would be an interesting comparison in the 1/4 because I guess you could extrapolate what the horsepower loss of the A/C compressor is by the MPH trap speed.

Also, the GM A6 compressors are not rated for very high of an rpm (5000 rpm max if I recall) - that is one reason you couldn't get a 4-speed SD455 with A/C or any RAIV with A/C. One missed shift and that compressor grenades.

[Keith Seymore]

Tracks prohibit the use of A/C during the run or in the staging lanes because of condensation and the potential for water on the track.

K

[bird72]

Originally Posted by Keith Seymore

Tracks prohibit the use of A/C during the run or in the staging lanes because of condensation and the potential for water on the track.

K

right! but in the 60's Hot Rod could have pulled it off....

[GT182]

Originally Posted by bird72

right! but in the 60's Hot Rod could have pulled it off....

Yep they could. Now days the a/c leaves a puddle. Almost as bad and the radiator overflowing and marking it's territory.

[bird72]

Originally Posted by 71GP76TA

FWIW - I hit 115mph in the SD with the A/C on... and it was still pulling..

my kind of fellow, ha

[goatman65]

U don't understand why anyone would even need a/c to drive a 1/4 mile. Come on it's only a few seconds.

[Chris65LeMans]

When I used to drive 4 cylinder Honda's, I always made sure to turn off the A/C before I needed power. "They" said that the A/C was a 10% of HP parasitic draw; when you've only got 130 to start with, every bit counts.

If you turned off the A/C at WOT, you actually did feel a significant boost.

If your question is a "is it a big difference" one; why don't trailered drag cars have power steering?

[Half-Inch Stud]

Good idea to drop the Ac clutch power on WOT. Even on Secondaries.

It was around 1984 ; I remember the AC clutch sparkler flames well....night drive on the PA Turnpike, saw some orange glow, that turned to sparkler flames. Clutch ring glowed orange. Forget if i had to cut the AC belt or just turn it off. Pretty much slammed the hood and resumed driving back to school.

[Greg Reid]

Don't most modern vehicles automatically drop the compressor out under hard acceleration? I know my '97 Dodge does.

[71GP76TA]

Originally Posted by Greg Reid

Don't most modern vehicles automatically drop the compressor out under hard acceleration? I know my '97 Dodge does.

Hmmm.. I never paid attention.. Next time I romp on my Challenger.. I'll have to see..

[rexs73gto]

Greg is right. ALL vehicles after 1966 with A/C have an override switch in the compressor to shut the comp. off when you go to WOT. thats wide open throttle. So if you go down the track at WOT which most of us do , there will be no difference in the performance of your car with or without the A/C on because at WOT the comp. is off & not taking any power away from your engine. The only way it would be different is if your only going down the track at half throttle.

[Overkillphil]

Exactly, all of the AC equipped vehicles I've been driving for many years have "cut out" or disengaged the AC compressor at WOT. Anyone who has floored a vehicle in the past few decades to get on a highway should have noticed the cold air dropping off to lukewarm from the vents.

[Lloyd-TX]

Originally Posted by rexs73gto

Greg is right. ALL vehicles after 1966 with A/C have an override switch in the compressor to shut the comp. off when you go to WOT.

Not so. When that feature was implemented varies from car-to-car.

ALL vehicles now have that feature - both to increase available power at WOT, and mostly to save the compressor!

[bird72]

I probably should have put this topic more seriously as I did have a logical reason.

It seems to me for street performance and air conditioning, a bad engine for that might be a high lift cam small block that winds to 7000 for top of power band HP with power band and gearing and the low end of power band beginning at 1500 rpm. Kind of an old school build.

The best engine for performance and air conditioning seems like it would be a good HP big engine, because with that comes good torque. It seems a 500lb tq motor would be far less affected by AC drag than a 350 lb tq smaller engine. So would a linear X % parasitic loss be across board true? or a sliding scale of loss actually.

And no, if you were going anywhere above 4500 rpm I would be turning AC off at least for a while. I'd be curious of any who have +400hp +500tq Poncho motors with AC and street gearing.

[rtanner]

if you run your car street car down the track w a/c on and put somebody into the wall because they ran thru your water, your going catch hell!!!!!!!!

[Alvin]

"Racing in the Streets"

"We take all the action we can meet
And we cover all the northeast state
When the strip shuts down we run `em in the street
From the fire roads to the interstate
Some guys they just give up living
And start dying little by little, piece by piece
Some guys come home from work and wash up
And go racin' in the street..."

[bird72]

dwallace, you are indeed right and my bad on the thread title and example. Really what I was wondering if any measuring of performance impact had been done on AC & hipo motors. It seems a big cube performance Poncho mill with it's relatively mild powerband should be a decent performer even with AC. Logic says don't run AC for full acceleration needs under load, regardless where. Going along with a big cube AC driver plan, seems gear ratio, tranny, etc all are important, more so with AC. 3.23 / 3.42 ratios seem to fit this....

[Greg Reid]

Maybe you can try it on the Dyno.