How does A/C affect performance?

[joeyb]

...just a lurker who's very interested in getting into an early 911 as a daily driver.

How does airconditioning affect the performance of an early 911? Will a sanden rotary compressor's load be so great as to affect the performance of a 2.0, 2.2 or 2.4? Will it cause the engine to overheat? Will upgrading to the oil coolers of the later 911's be a good solution that will allow it to sit and idle in traffic on a hot day?

I know of a couple of guys, one with a '72S and another with a '65, both of whom have done away with the compressors because according to them it affects performance. Hence, the cars are just used for early morning weekend runs.

Is this really the case? I'd really like to have one and have it as a daily driver and have airconditioning.

Thanks beforehand for any advice you gentlemen may have.

joey

[Jens]

Yes Joey. It takes horsepower to run the compressor. It takes a lot less to just run the belt and the pully assembly on the compressor when you don't have the AC running, so if you need the power that's running the AC to go to the rear wheels, just shut off the AC for that time.

Remember that the AC components and the refrigerant weigh a bit, so you are also spending horsepower to just move that extra weight down the road whether you turn it on or not.

If you live where it is really hot and/or humid much of the time, having AC might give you a lot more enjoyment out of the car, and reason to drive it more. Pretty darn good reasons!!

[pwd72s]

I once had a 1970 911T, purchased new with air. It worked great...just great...as long as the ambient air temp didn't exceed 74 degrees f.
(edit) Joey, I just noticed your location. By any chance do you know Gabriel Valdez there? He's very much into the early 911, and would probably be well versed on which systems work there & which don't. I certainly hope there have been advances made since 1970. My experience with the T made me decide to never buy an air conditioned 911.

[joeyb]

Thanks for the advice! Yes, I know Gabby Valdes, and in fact it's he that I was referring to with the 72S (absolutely beautiful car!). I was talking to him and another fellow last weekend after one of their weekly morning runs, and he was telling me how he had taken out the air-conditioning system because it affected performance. He wasn't very specific on what it was, whether it was weight, overheating or pulley drag.

I once had a 1500cc engined VW bug in which I had installed an airconditioner using a small rotary Sanden compressor with 2 fan cooled condensers. The airconditioner blew ice cold even during the summer months. Pulley drag with the compressor's magnetic clutch engaged was noticeable but didn't present that much of an issue considering the advantages. Engine heat on the other hand did present problems as there was a distinct degradation in performance during very hot days in traffic conditions. The reason may have been because I didn't bother putting in an external oil cooler. But that was a bug engine which could easily be torn down and fixed or entirely replaced. But the same cavalier attitude with an early 911 engine would be nothing short of sacrilege not to mention expensive.

I've always thought that with the use of oil coolers and fans meant for the later big displacement 911's and 930's, there's probably no reason that an early 911 can't have air-conditioning which can idle all day sitting in traffic with the air conditioning blowing ice cold and the temperture needle hovering at the normal range; every bit as comfortable as a modern japanese car. Is this a reasonable assumption?

[RandyWebb]

I think that's right - the manf. Sanden comes to mind - but I really don't know. You might do a search on Pelican. I know those guys in SoCal have found something better - just don't know what.

[tfmcmahon]

It didn`t take long to figure out why I found two low mileage vintage cars here in Tucson.It has been 100 degrees since around the 1st of June and you simply can`t drive them here in the summer with or without air.Targas are ok,but coupes are simply out of the question.I drove a 72T coupe from Calf. to Arizona in June and the only way I made it was a bucket of ice and a cold towel.Sort of a Lawrence of Arabia look.We have rust free cars,but you don`t rack up any miles for 6 months.TFM