Parallel-flow condenser for late 5-speed?
 

Has anyone seen/tried one of these:

http://www.americancondenser.com/ind...1991&model=928

Looks legit, although only available for '87-'91 5-speeds. The 5-speed GTS has the smaller auto condenser because it has the manual transmission cooler, and the earlier cars have a slightly different hook up for the high-side hose. This would greatly increase the efficiency our A/C systems, especially during low air flow situations.

Dan
'91 928GT S/C :eek: 475hp/460lb.ft

Interesting ... so parallel flow is a newer, better design?

Yes, there are three main types of automotive condensers: tube/fin, serpentine and parallel-flow. Parallel-flow designs are the newest and most efficient. Pretty much all newer cars have condensers of this design.

http://www.ackits.com/parallel/condenser1.jpg

Dan
'91 928GT S/C :eek: 475hp/460lb.ft

Are our OE condensors tube and fin? How much improvement is possible with the newer design?

At low air flow conditions - I'd expect that there would be insufficient time in the heat exchanger to dissipate sufficient heat - seems to me that therefore it would actually be worse under low flow but better under high air flow...

What is the theory that would make it better...?

Alan

How does your current system perform?
The stock, R12 filled A/C system in my 81 will blow in the low 30's on a 100 degree day at idle sitting in traffic. Problem is, the condenser is huge. I would expect a newer style like this would perform the same, with a smaller footprint.

Or is this designed to work better with R-134a?

"Tampa 928s" just installed one of these new style condensors on an 80 euro the other day and had nothing but good things to say about it. Maybe he'll chime in and comment.

80 Euro R-12 converted to R-134 I thought it was too thin and too short, well proof is in the using. Getting down to 35 degrees in the Florida whether it works great I paid $199.00 for mine! :corn:

Shawn call me!

any pics of it before installation comparing it to the size of the factory condensor?

I have experience with replacing dual-pass serpentine type condensers with ones of a parallel-flow design on other cars. Both condensers were identical in size. My experience is that at times of low air flow and high ambient temps, the serpentine condenser heat transfer efficiency was not sufficient to produce freezing evaporator temperatures. With the parallel-flow condenser, even at 100 deg F ambient the system still cycles off the anti-freeze switch. At times of high air flow since the serpentine condenser was sufficient to bring the evaporator to freezing, I am unable to say whether or not the parallel-flow condenser is any better, but that becomes a moot point. This was in systems converted to R134a.

Keep in mind that the parallel-flow design usually incorporates multiple passes, not single pass like a coolant radiator. The design of the tubes also increases the effective surface area for heat dissipation.

Dan
'91 928GT S/C :eek: 475hp/460lb.ft

This may or may not be the same condenser. The one I listed is only for '87 and newer 5-speed 928's. If it is the same, it could explain why it does not fit so well. Would it be possible to take some pictures of your installed condenser?

Dan
'91 928GT S/C :eek: 475hp/460lb.ft

These folks say that parallel is best.
http://www.techchoiceparts.com/content/condenser.aspx

So do these techs.
http://acsource.net/acforum/viewtopi...t=4361&start=0

So does this blog - and he gives sources.
http://www.e38.org/pparish/cond.htm

These folks say that parallel have serious problems with clogging.
http://www.4s.com/Upload/Four%20Seas...COMPARISON.PDF

It seems perfectly obvious to me that a parallel-flow condenser would be much more difficult to properly flush. In the interest of maximizing surface area (and therefore heat exchange efficiency), the holes inside the tubes are very small and numerous, and there are also multiple passes for refrigerant to flow through. On the other hand, the condenser I referenced can be had for under $200, so in the event that I had a bad failure that introduced debris into the system I would just go ahead and replace the condenser at that price.

Dan
'91 928GT S/C :eek: 475hp/460lb.ft

Interesting Dan - I've been looking at possible parallel-flow replacments for my 928's (manual S4's).

Closest match I've found is from a Hyundai i30 petrol, or Hyundai Elantra - 610x391x22mm and side fittings, plus an accumulator, although it would need new fittings brazed onto it to fit the 928 hoses.

If anyone has direct experience of these and dimensions are suitably large, I'd buy a couple - its not clear whethet Tampa's talking about this same one?

If your compressor grenades then you WILL have to replace the condenser, but for $200.00 who cares. If you look at the R-12 vs R-134 condenser the R-134 channels for the gas are a lot smaller. The replacement is smaller still but has many more fins and works great on the 80. When I replaced it I was skeptical that it would dissipate enough heat but was surprised at the end result. Sure beats $700.00 for a factory replacement besides it weighs a lot less, for that extra speed we are all seeking :icon107: