Another boring AC thread - installing a 993 condenser in a 3.2 Carrera

[NathanR]

Originally Posted by Ronnie's.930

Nathan, I forgot to mention that the pictured bag is labeled 450 grams, and I used a whole bag and about a quarter or so of a second bag.

Thanks, and I can't say definitively what kind of a difference insulating around the evaporator housing made with regard to performance (I made several changes at the same time), but I did it primarily for the heck of it, and it makes sense to my limited intellect (right, Eric?!?!), but as you are aware, I have seriously cold a/c even in burnass TexASS, so maybe it helped . . .

My climate hear is nowhere near as demanding as TexASS, or the southern states. On the other hand, I park next to a muffler shop every day and it would easy to ask if they have that stuff.

[Tippy]

Originally Posted by Ronnie's.930

You are now, Cory; guard yer loins, bro !!!!

Me loins are sealed shut.....

[Wavey]

The insulation kit that came from Rennaire was an industrial HVAC product. I was a large sheet of heavy aluminum foil bonded to a thick, black insulating foam (1/8"?) with an adhesive back. It wrapped/molded around the evap box so it sealed air leaks and reflected ambient heat under the trunk lid. The evap box was then a pretty tight fit into the smuggler box, but there was some room left to cram in more insulation.

[wwest]

Anyone think of covering the interior of the smugglers box with a spray can of undercoating?

[wwest]

Originally Posted by NathanR

Regarding fans, I hooked it up to a power source and it pushed impressively, and I noted the polarity. I didn't note the direction it was spinning, nor can I even see it at this point! Will check when I get it all hooked up.

@CG, thanks for the encouragement.

A larger fan would push more air, but in the process of getting everything to fit together I was glad I had a little wiggle room. Without those considerations, An 11" would have fit perfectly, 12" would have overhung the edge a bit. On the outboard side there is a little flange at the top that interferes.

As a general rule you can block the overhang (within reason) and still get more CFM through the condenser than with the 10".

[wwest]

Originally Posted by NathanR

I'm not concerned too much about this but will observe pressures once I get it up and running. I already fabbed a simple heat shield that can mount on the bottom of the bracket if warranted

You might wish to take note that at least one vendor markets ONLY the condenser that mounts in the front of the rear wheelwell....

It appears to me that mounting a condenser near the engine/exhaust/catalyst as a first effort sometimes requires a second condenser to get the "job" done.

Logically one would think that the first effort marketed/offered would/should be the front of the rear wheelwell.

[wwest]

Originally Posted by SilberUrS6

It's a stupid experiment, and won't tell you anything useful about anything. Elsewhere I have explained carefully about radiant heat transfer and emissivity. The bottom line is that in an non-turbocharged automotive environment, radiant heating is not that much of an issue. For cars running turbos, the turbo, exhaust manifold and downpipe can get to yellow heat, and that can affect fuel and cooling system parts. But that's not applicable here, because the catcon never gets to any kind of heat that shows in the visible range. You do not have to worry at all about radiant heating. As in, put the idea out of your mind, because it just doesn't matter at all.

Are you really saying that "visible" heat, cat/exhaust GLOWING, is a worrisome matter but heat not visible to the human eye is not..?

Isn't that an admission that the IR from the engine/exhaust/catalyst has some level of adverse effects?

So what is your threshold?

With our cars it is clear that every little bit of improvement to the A/C must/should be paid attention to, especially so when there is an obvious, virtually NO COST solution.

So why Op to ignore this aspect..?

Op purchased ($100 ) the 993 condenser from our sponsor, and custom building the required hoses, so no vendor is being "dissed" by suggesting a different mounting

[wwest]

Originally Posted by SilberUrS6

Radiant heat transfer is so small in comparison to the mass heat transfer (air across the condenser fins) that it doesn't even matter.

In other words some portion of the fan CFM is being used to overcome the engine/exhaust/catalyst adverse effects...

What % would be your guess..?

[SilberUrS6]

Originally Posted by wwest

In other words some portion of the fan CFM is being used to overcome the engine/exhaust/catalyst adverse effects...

What % would be your guess..?

Why guess? Do the calculations yourself.

If you want to do a little research on your own, you'll need to learn about the following:

Radiative vs. conductive heat transfer.
Emissivity.
The temperature of the condenser at operating pressure.
The surface temperature of a stainless steel catcon housing at steady-state engine operation.

For grins, you can triple the operating temp of the catcon and plug the number in. The results will make you laugh out loud.

[wwest]

Originally Posted by SilberUrS6

If you are interested in my quick calculations, PM me. I doubt you'll get the same from wwest, but I want to see if he actually *can* do the calculations.

If you want to do a little research on your own, you'll need to learn about the following:

Radiative vs. conductive heat transfer.

Emissivity.
The temperature of the condenser at operating pressure.
The surface temperature of a stainless steel catcon housing at steady-state engine operation.

For grins, you can triple the operating temp of the catcon and plug the number in. The results will make you laugh out loud.

None of the above matters even one iota.

The fact is, placing the condenser farther away from a >400 degree heat source improves the condenser efficiency.

Run your car hard for long enough to bring the catalyst up to operating temperature, stop the engine, and then place your hand in the approximate area of the rear mounted condenser. Now repeat the procedure but place your hand in the approximate position of the ZIMS condenser.

Think for minute, what would your opinion be had Porsche placed the 964/993 condenser in the rear of the wheelwell and an aftermarket supplier came up with a kit to move it to Porsche's actual choice?

No market for the kit?

Sure.

[NathanR]

Originally Posted by wwest

None of the above matters even one iota.

The fact is, placing the condenser farther away from a >400 degree heat source improves the condenser efficiency.

Run your car hard for long enough to bring the catalyst up to operating temperature, stop the engine, and then place your hand in the approximate area of the rear mounted condenser. Now repeat the procedure but place your hand in the approximate position of the ZIMS condenser.

Think for minute, what would your opinion be had Porsche placed the 964/993 condenser in the rear of the wheelwell and an aftermarket supplier came up with a kit to move it to Porsche's actual choice?

No market for the kit?

Sure.

I think the point was, while you may be theoretically correct, in practical terms, it just doesn't matter. It sounds to me like Eric has done the math, and you haven't. Just saying.

Me, I'm waiting to make a quick observation once I get up and running, but I'm not really concerned. I doubt it's a problem, and it's easily fixed if it is.

[NathanR]

Originally Posted by wwest

Are you really saying that "visible" heat, cat/exhaust GLOWING, is a worrisome matter but heat not visible to the human eye is not..?

With our cars it is clear that every little bit of improvement to the A/C must/should be paid attention to, especially so when there is an obvious, virtually NO COST solution.

So why Op to ignore this aspect..?

your "no cost" solution is actually very expensive to me -- In terms of the number of hours it would take me to start the bracket fabrication process over again.

[NathanR]

Originally Posted by Wavey

The insulation kit that came from Rennaire was an industrial HVAC product. I was a large sheet of heavy aluminum foil bonded to a thick, black insulating foam (1/8"?) with an adhesive back. It wrapped/molded around the evap box so it sealed air leaks and reflected ambient heat under the trunk lid. The evap box was then a pretty tight fit into the smuggler box, but there was some room left to cram in more insulation.

Didn't realize the kit came with insulation. Good to know. I'll wait and see what comes before I buy the stuff Ronnie used. Did you have difficulty getting the box back in?

[NathanR]

Another question. On what fittings do you use Nylog? I noticed the service port adapter seems to be a flare fitting. Should I use Nylog on the face of the flare? Or on the threads? Or not at all?

I've noted others recommend NOT using it on o-rings.

[wwest]

Originally Posted by NathanR

I think the point was, while you may be theoretically correct, in practical terms, it just doesn't matter. It sounds to me like Eric has done the math, and you haven't. Just saying.

Me, I'm waiting to make a quick observation once I get up and running, but I'm not really concerned. I doubt it's a problem, and it's easily fixed if it is.

Near Eagle?

Just picked up my '78 from there, on loan to my nephew for awhile.

I doubt that Boise climate will be a challenge for your system even if there is degradation from the radiant heat.

[Wavey]

Originally Posted by NathanR

Didn't realize the kit came with insulation. Good to know. I'll wait and see what comes before I buy the stuff Ronnie used. Did you have difficulty getting the box back in?

I think the evaporator box insulation kit was a separate item from the Rennaire evaporator itself; maybe $50 or so? I checked Rennaire's site and I don't see it mentioned anymore so maybe they've dropped it. I think the kit included a round foam seal for the port where the evap box exit hole met the hole to the interior ductwork, inside the smuggler's box.

The box was a minor struggle to remove and replace, a little more so after the insulation was added. It was a nice snug fit on final reassembly.

I'm going to search again for photos or posts from the project. The whole idea was to seal the evap box to prevent air leaks so as to get max efficiency from the fan, and also to insulate to keep the cold inside and to keep the underhood heat out. I'm sure you can deal with those issues separately; seal up the evap box, insulate the hell out of the smuggler's box and be sure the seal to the chassis is good.

BTW, I had to replace my temp control, and feeding that capillary tube through the console and firewall and into the evap box was a M@+#&r#@%er. You get my drift. Lots of finesse required. Not sure if you're getting into that?

Originally Posted by NathanR

Another question. On what fittings do you use Nylog? I noticed the service port adapter seems to be a flare fitting. Should I use Nylog on the face of the flare? Or on the threads? Or not at all?

I've noted others recommend NOT using it on o-rings.

I believe that's intended to be a thread sealant. I honestly can't remember if I used it on all areas of the joints. I think I fitted the O-rings dry then used the Nylog on the outside before running the nuts down.

[DaveMcKenz]

Hi Nathan,
I used lots of Nylog on my system. I think of it as a thread lubricant, so the surfaces can seat properly. I think it is made from a/c refrigerant oil, and becomes quite viscous. Within reason I don't think it has much of a downside, such as clogging your system. OTOH I think Griff assembles his stuff dry, but he's a pro with lots of experience.
BTW, I really like your system, and IF my Wwested design does not perform well enough, yours will be my next step. I already have most of the parts and will just need one hose made.
Thanks for sharing,
Dave

[Ronnie's.930]

Regarding goo on threads and o'rings - I use a thin smear of silicone grease on all of the o-rings and a tiny dab of nickle anti-seize on all threaded connections. I always use a drop of oil on the flare portion of any flare fitting (don't have those in my a/c system, however).

[Wavey]

Originally Posted by DaveMcKenz

Hi Nathan,
I used lots of Nylog on my system. I think of it as a thread lubricant, so the surfaces can seat properly. I think it is made from a/c refrigerant oil, and becomes quite viscous. Within reason I don't think it has much of a downside, such as clogging your system. OTOH I think Griff assembles his stuff dry, but he's a pro with lots of experience.
BTW, I really like your system, and IF my Wwested design does not perform well enough, yours will be my next step. I already have most of the parts and will just need one hose made.
Thanks for sharing,
Dave

I think Dave nailed it. I think I did use a small amount to lube the O-rings too.

Refrigeration Technologies: Products: Nylog Blue

[NathanR]

Oh look, my 134a showed up today