Jim Florance

I have a 1970 911. I spent this past winter restoring it and turning it into a "trackable" RS Clone. I want to put air conditioning in it. My problem is that the two closest tracks are both in the Mojave Desert! (Willow Springs and Button Willow) I do not have a trailer an frankly, the car is so much fun to be in, I drive it to and fron the track. I've got a post on the "Upgrades/mods" forum, but I really need more input. Any one with any 911 AC or anyone that has any ideas where I can find one of the old Dealer Installed AC Systems, Please comment, I need your help. Oh, by the way, I now have a 2.7liter case in the car, I understand that motor requires a different compressor. Please give me your advice!!!!!!!!!!!!!
Thanks
Jim

rfuerst

Hello Jim,if I were you I would start out by getting in touch with Performance Aire-www.scottsind.com-or Griffiths-www.griffiths.com-from what I have heard these 2 companies have lots of experience with Porsche AC.They can tell you what works and what doesn't,I'm sure they can answer your questions regarding a compressor for your year also.Good luck.

Hladun1

I rebuilt the A/C system on my 78 SC. I had the original evaporator. I had new hoses made up (biggest cost item), bought a deck-lid condenser and compressor bracket from Parts Heaven and got a used Sankyo compressor out of a wrecked SAAB for $20. I use only the single deck-lid condenser. For controls I have the original three speed fan, a GM evaporator control valve and a 300 psi compressor shutoff. (For R134a a 350 psi shutoff would be better.)

The most important thing I did was get a pancake fan from JC Whitney to blow more air through the condenser (search on my name in the Pelican form for other posts on this topic). I then charged the system with R134a. I get 47F vent temperatures when it’s 95F (dry) outside.

Here is the secret…..you must get more airflow through the deck-lid condenser or the system just can’t work. The problem with the Porsche A/C systems on older cars is that they can’t reject heat.

In your really hot climate, I would also look at the added Giffths rear fender condenser. But bring lots of money for that one.

willard

And don't forget....

All the airflow used to cool your engine will now be significantly preheated by the condensor in the air intake path.

Gino

hladun1-
that pancake fan... I assume you mounted it under the condenser coils inside the engine bay. and, it didn't affect normal cooling/breathing of the engine bay? I was also curious whether or not it was 'on all the time', switched, or temp -pressure activated?

I'm assuming this helps a whole lot for cooling during traffic.

and speaking of traffic, can the fan direction be reversed so the fan would push out air through the condenser and assist engine bay cooling?

Jim Florance

Hello:
Wanted to thank everyone that responded: I contacted Performance Aire and Charles Griffiths. and I think I have everything worked out. As it stands now, I'm going to have Performance air do the work. they will provide the dryer, AC Lines, The Behr controller / reciever / and the compressor. They use a true "Rotary" compressor they say can handle up to 11,000rpm w/out grenading. Since the motor I had built this winter has 906 Cams and was built for high rev operation, the Rev limit of the compressor was a big concern. The motor will rev high, but nowhere near 11,000rpm. It is nice to have a 2500rpm cushin for a substanial safety margin.
Performance aire uses a heavy duty Condenser that bolts under the car near the front of the pan. Since I'm going to be tracking the car and competing in autox events, I was worried that occasional spins into the weeds and my bad habit of crunching traffic cones, I passed on their unit and will be using Griffith's rear fender mounted unit. Great design, thanks, Rfuerst, Charles Griffith really knows AC! I think his unit will work very well on my car. Hladun: your responce got me to spend some time reasurching AC mechanics. It was very useful. I learned a lot and because of your input, I made sure that when the system is installed, It will include a pancake fan to draw add'l air throught the deck-lid condenser. Willard: I knew that AC Condensers and compressors are the source of a lot of add'l heat. to compensate for this problem and to help spill the add'l heat resulting from a much bigger motor than my caar originally had, I have installed an original 935 cooler I bought from a woman who was parting out her old track car. I used 7/8" copper lines to get the oil to the cooler and also put one of those finned aluminum sleeves around the oil filter. Hopefully, this will take care of any heat issues I encounter. As usual all the feedback was really helpful, Rennlist is the best source for information I have yet to find on the net. Thanks for all your input.
Jim

Hladun1

Gino,

Yes, it’s mounted under the condenser coils over to the left side. I had to move my coil and cut off the intake air horn to give it space to fit. Don’t check fit by slamming the deck lid! I wired it in parallel with the compressor clutch so it works only when the compressor is on.

My fan actually blows out of the engine bay so it has double the effect on condenser airflow. There is no noticeable affect on engine breathing because the draw of the engine and the engine cooling fan is actually quite low. (Look up the Pelican posts). The added air circulation would probably keep the engine bay cooler but I think it’s quite negligible.

It does help a lot in traffic because the condenser air flow is high. You can also open the deck lid without frying your compressor.

wwest

Confused am I.....

The engine cooling fan pulls airflow through the top engine cover, "hood", (now through the new condensor) forcing it down through the cylinder cooling fins/vanes and out the bottom of the car.

If your pancake fan is blowing airflow OUT through the condensor then you have two fans pulling the same air in two directions. NOT good news.

Even if you reverse the direction of the pancake fans you might still find that at high engine RPM they are providing a significant airflow restriction.

If, at high engine RPMs, the pancake fan(s) are not capable of providing equal airflow levels to the engine fan itself then the pancake fans will end up being electricity generators (DRIVEN by the airflow rather than DRIVING the airflow) and thereby restricting engine cooling airflow.

Hladun1

wwest,

The pancake fan covers about 1/3 of the opening area. Airflow to the engine and for condenser cooling occurs through the unrestricted 2/3. If I recall correctly (and for the third time check the Pelican posts) the air speed through the opening is about 14mph which is quite low. If you think the pancake fan will turn backwards then you are giving the engine fan far too much credit. It works!

craig001

For your cone crunching, Porsche made a bar the bolts under the front of the car to protect things there. If your car doesn't have one then it might do you well to find one. I have one from when I thought I was getting a 911 (that's where an independent PPI comes in handy) and could let you have it for what I have in it. I got it off eBay so it shouldn't be too bad.

willard

May I ever so politely ask you where the airflow being exhausted by the pancake fan is coming from?

With "some" of the exhausting airflow entering in the 2/3s area isn't it "robbing" the engine of some cooling airflow capability?

I'm quite sure that wouldn't be a problem except, maybe, in extreme environments, Tucson or Memphis in August, or HARD track days.

JackOlsen

Jim, if it's not too late, you might want to reconsider your condenser decision. I've had both the rear fender model and the Performance Aire under-belly model. The under-belly model is much better.

I also drive out to Buttonwillow and Willow Springs, in a black on black car, without a trailer, so we're in the same boat. With new hoses, new receiver/dryer, a front condenser and the under-belly condenser, I get 37-degree output in 85-degrees ambient with R134A. I eliminated the rear decklid condenser, since it heats up the motor anyway (see the above posts), and adds weight where you don't want it.

The same can be said for the rear fender condenser -- it adds weight behind the motor, which is the worst possible place to add it. It also adds the weight of a fan and ducting back there. Especially for a track car, this is the opposite of what you want.

The under-belly one is also tough as nails. You can lift the car on it. It holds up even to my abuse:

<img src="http://forums.pelicanparts.com/uploads/DirtTrack.jpg" alt=" - " />

ZCAT3

Jack - I am working on getting the AC working in my 930 and had contacted Griffiths. It is $2000 just for the parts. I am curious about what you did. You removed the rear decklid condensor and installed the under-belly condensor only? What did it cost for this system?

JackOlsen

I put in new hoses, a new dryer/receiver, and added the under-belly condenser. I did it along with a lot of other work, and in two different iterations (the first with the rear fender condenser), so I don't know what it cost.

I'd talk to Scott's Independent/Performance Aire about a whole system, and what it would set you back.

porschefied

Hello P-folk,

Can you SEE the under-car condenser? Is it visible or hidden? If people could post pix that would be good. (Currently I have broken original A/C on my 1977.)

Thanks!

-Shelley Fleming