AC and track use ??
07-14-2010, 03:11 PM
#16
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Closed cockpit cars at Lemans must run AC or be able to keep the cabin temp below a certain level...I saw a pic of the 997 RSR AC system somewhere...
07-14-2010, 06:42 PM
#18
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Yes, RSR's have A/C.
Funny story about A/C and Hurley Haywood: back somewhere in the 70's, he was racing some model Porsche, not sure which (he said it in his story, but I forgot) and it had to be a homologation of the actual street car. So it was, right down to the A/C. So, he pulls into the pits for service and leaves. His crew chief sees a puddle under where he was and panics. He goes to the puddle to see what it is, and it's water. He screams into the headset "Hurley, are you running the A/C?" to which Hurley replies "Yes, why?", crew chief says "Turn it off, it's draining power and slowing you down". Hurley then replied "it's hot in here, and I'm in the lead....I'm keeping it on!"
Funny story about A/C and Hurley Haywood: back somewhere in the 70's, he was racing some model Porsche, not sure which (he said it in his story, but I forgot) and it had to be a homologation of the actual street car. So it was, right down to the A/C. So, he pulls into the pits for service and leaves. His crew chief sees a puddle under where he was and panics. He goes to the puddle to see what it is, and it's water. He screams into the headset "Hurley, are you running the A/C?" to which Hurley replies "Yes, why?", crew chief says "Turn it off, it's draining power and slowing you down". Hurley then replied "it's hot in here, and I'm in the lead....I'm keeping it on!"
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07-14-2010, 06:53 PM
#19
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Rotary compressors use less power and can handle the higher rpms much better than a conventional piston units.
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Larry Herman
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Larry Herman
2016 Ford Transit Connect Titanium LWB
2018 Tesla Model 3 - Electricity can be fun!
Retired Club Racer & National PCA Instructor
Past Flames:
1994 RS America Club Racer
2004 GT3 Track Car
1984 911 Carrera Club Racer
1974 914/4 2.0 Track Car
CLICK HERE to see some of my ancient racing videos.
07-14-2010, 08:30 PM
#22
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07-14-2010, 08:40 PM
#23
The Penguin King
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07-14-2010, 08:42 PM
#24
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It wont make your engine run any harder, its already running as hard as it can when you are WOT. the only difference is some of the power will be diverted to the AC compressor. Kind of reminds me of the discussion about the extra balast weights making it harder on an engine.
Here is an idea. get a switch from the brake system and WOT system, so that it is cycled on if you are braking or not at full throttle. (or a AC kill switch only at WOT) then, you will have a little braking assist too!
as long as the compressor can handle the RPM under load, there should be no issues. I know Ill be wishing for AC this next Thunderhill race, (100F temps) But, heck, its only a 30min race!
Here is an idea. get a switch from the brake system and WOT system, so that it is cycled on if you are braking or not at full throttle. (or a AC kill switch only at WOT) then, you will have a little braking assist too!
as long as the compressor can handle the RPM under load, there should be no issues. I know Ill be wishing for AC this next Thunderhill race, (100F temps) But, heck, its only a 30min race!
07-14-2010, 08:45 PM
#25
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Hard to say, but I dont know if I would want a hot condenser siting in front of my radiator during a race. Ive never measured the temp of one of these when the AC is on . But, if you cant keep the engine cool enough, i guess that would be the answer.
In most modern cars, the AC compressor will kick off under full throttle. I suspect that the constant kicking off & on for a 20-30 minute track session, in addition to the added heat load due to the AC operating on track, does not help most cars. 
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07-14-2010, 09:36 PM
#27
The Penguin King
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Am I hallucinating, or did MK just quote VR in a positive manner? Can somebody check the weather report in hell please? 
07-14-2010, 11:27 PM
#29
Three Wheelin'
When I first raced my 944, somebody told me that if your car overheated a little in a race, that turning on the AC turned on the second fan on the radiator. It seemed to work. When I took the AC out of the car, I left it so I could turn the big **** for the AC on an early 944, and the second fan would come on. That definitely worked.
Bill Seifert
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07-15-2010, 07:38 PM
#30
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"logical" manner, not "positive". "Positive" shows bias.
What if the condenser was not in front of the engine radiator, would it still make the car run hotter?