Backfitting a Sanden or R4 Compressor
Thread Starter
Team Owner
Joined: Jul 2004
Posts: 40,380
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From: Redondo Beach, California
Backfitting a Sanden or R4 Compressor
I'm looking for a Serpentine set-up for my BB 1970. It currently has the factory AC system with a R6 compressor. March and Billet Specialties Serpentine systems use Sanden compressors. The GM Performance Part catalog has a BB Serpentine system that incorporates a R4 compressor.
Can I use either the Sanden or R4, in lieu of the R6, with the stock 1970 AC? I suppose I should the factory AC to be compatible with R134 and use R134?
Next question, how do the Sanden's and R4's compare? Are they about equivalent? Is the R4 heavier? Using the R4 will dramatically reduce the cost of the Serpentine system I buy. The GM Serpentine kit, including water pump, alternator, compressor, PS pump, is about $740. The Billet Specialties system is about $2200.
Can I use either the Sanden or R4, in lieu of the R6, with the stock 1970 AC? I suppose I should the factory AC to be compatible with R134 and use R134?
Next question, how do the Sanden's and R4's compare? Are they about equivalent? Is the R4 heavier? Using the R4 will dramatically reduce the cost of the Serpentine system I buy. The GM Serpentine kit, including water pump, alternator, compressor, PS pump, is about $740. The Billet Specialties system is about $2200.
Melting Slicks
Joined: Mar 2007
Posts: 2,100
Likes: 12
From: Frederick Maryland
I can't answer all your questions as I'm simply not sure enough to say, but I'll discuss what I feel comfortable answering.
The Sanden compressor is a more efficient unit...much more modern than an R4 which dates from the '70s. That being said, the R4 is a less expensive unit and works perfectly fine...I have the GM Performance serpentine kit installed on a small block on one of my cars. The R4 doesn't have the cutting edge look and "WOW" factor of the Sanden...especially if it's polished or chromed, but as I said, you have to pay to play...I saved the $ and am perfectly satisfied.
GM provides the R4 with their kits because of cost considerations, and that they must have a ton of them in inventory, so why not use them up in these kits?
You can use either the Sanden or R4 with the stock a/c...no problem there. The refrigerant doesn't care what compressor it's being pumped through. The issue you'll run into is the hose ends are different I believe. You have to have new hoses made up, which isn't a real issue, but does add to the expense. That may be a plus, as R134a refrigerant runs at higher pressures than R12, so replacing your nearly forty year old hoses would be a prudent thing to do anyway.
I couldn't tell about the weight difference between the Sanden and the R4, but either is substantially lighter than the old A6 you have now.
I would definitely go with the GM Performance kit. Your car has a front hinging hood...you won't be able to show off the March or Billet Specialties parts very well anyway...especially of you keep the fan shroud. The dollar savings is a real bonus. You will have to buy a reverse rotation fan unless you go with electric fans.
As nice and reasonably priced as the GM Performance serpentine kit is, GM provides it with a rebuilt alternator...not new. The alternator in mine failed in 600 miles. I tossed it and installed a Powermaster.
The Sanden compressor is a more efficient unit...much more modern than an R4 which dates from the '70s. That being said, the R4 is a less expensive unit and works perfectly fine...I have the GM Performance serpentine kit installed on a small block on one of my cars. The R4 doesn't have the cutting edge look and "WOW" factor of the Sanden...especially if it's polished or chromed, but as I said, you have to pay to play...I saved the $ and am perfectly satisfied.
GM provides the R4 with their kits because of cost considerations, and that they must have a ton of them in inventory, so why not use them up in these kits?
You can use either the Sanden or R4 with the stock a/c...no problem there. The refrigerant doesn't care what compressor it's being pumped through. The issue you'll run into is the hose ends are different I believe. You have to have new hoses made up, which isn't a real issue, but does add to the expense. That may be a plus, as R134a refrigerant runs at higher pressures than R12, so replacing your nearly forty year old hoses would be a prudent thing to do anyway.
I couldn't tell about the weight difference between the Sanden and the R4, but either is substantially lighter than the old A6 you have now.
I would definitely go with the GM Performance kit. Your car has a front hinging hood...you won't be able to show off the March or Billet Specialties parts very well anyway...especially of you keep the fan shroud. The dollar savings is a real bonus. You will have to buy a reverse rotation fan unless you go with electric fans.
As nice and reasonably priced as the GM Performance serpentine kit is, GM provides it with a rebuilt alternator...not new. The alternator in mine failed in 600 miles. I tossed it and installed a Powermaster.
Last edited by Roughrider; Jun 5, 2008 at 08:39 PM.
Intermediate
Joined: Jul 2005
Posts: 38
Likes: 0
From: Rockbridge Ohio
A Sanden compressor can be adapted to fit a GM serpentine bracket. All you need are two C shaped brackets that have the same radius as the mounting ears on the Sanden compressor and a couple of spacers.
