Griffith's fender condenser dimensions

[rusnak]

I just got back from an appointment that required lots of freeway and stop and go driving. I left the AC on. This time when I stopped, I took a measurement (Sears Craftsman infrared thermometer) and got a bigger temp difference into and out of the rear condenser. 155 on the inlet side, 125 on the outlet side. I also have the procooler, which cools the freon about another 15-20 degrees.

The cat, by the way, got up to 605F. I hold the laser beam about 4" from the surface that I'm measuring, and try to pick a surface with low reflectivity. Maybe my cat is wearing out and plugging up? That just seems way too hot to try to put a cooler in there a few inches away.

[kuehl]

Originally posted by rusnak
I agree, Ron. But if it's a street car then it has a cat, and it should have a state of the art heat shield between the cat and fender condenser.

Well, the first system did not have a "state of the art heat shield" and it performed very well. The second verision did not not have, nor the current Rev 3. However, all have heat shields for the hoses.

When we designed the unit and tested it, radiant heat was considered but has never been an issue. "Convection" (heat) is always an issue and the current Rev 3 pretty much covers the last base.

Let me ask a question: We (I) read so many posts with concern about heat in the rear fender. A good question, when sitting in a chair. How many of the poster's have tried a fender condenser or driven in a car with one as opposed to just wondering about it?

[Mysterytrain]

This is always an interesting read. My car is cat-less so one less issue regarding that heat source. Actually the system that intrigues me most is a marriage of the C2 condenser/fan and the Kuehl front rear condenser. I love the idea of the Performance air triple pass deck lid condenser but I think it would really reduce air flow.
My 78 came thru without the front condenser. I've been collecting parts to install one but I must confess the idea of hacking holes into a rust free tub doesn't give me a woody. Kinda of makes the idea of dual condensers in the rear fender more appealing to me. One of the things that interests me most about the C2 unit is the beefy fan and cowl. Looks like it would move some serious amounts of air thru the condenser.
I also have a question for Charlie..Is fan noise a factor with the duehl kuehl condenser mounted so close to the driver?

[rusnak]

Kuel: I haven't driven the rear condensor setup, I confess. But an honest question: if heat defeats the rear decklid condensor, and that temp environment is around 200F at the fan, then wouldn't the 600F at the cat be worse? True, airflow helps to direct heat away, but you have to stop or slow down at some point. And the rear fender condensor IS awfully close looking to that hot cat. Enough to make a person wonder, you know?

I remember reading some tech articles that pretty much concluded that the 964 condenser is superior, but the 993 is even better. Both required hacking and welding at least on par with adding a front condensor hole in the front trunk.

Has anyone added a 964 fan to the 3.0 and 3.2 fan hoop? Will it work? Those curved blades might move more air, and thus help the cooling and AC condensor.

[kuehl]

Originally posted by Mysterytrain
I also have a question for Charlie..Is fan noise a factor with the duehl kuehl condenser mounted so close to the driver?

The sound is subjective. I guess I could hook up a my old decibel meter and maybe borrow a something to note the frequencies... but then we would have to raise the price!
(joke, laugh).
Both Kuehl units (the behind the LH rear tire Kuehl and the in front of the LH rear tire DuehlKuehl) are mounted on vibration mounts. Each have a fan. The rearward unit has a larger fan than the forward unit. The forward unit's fan "noise" is at a higher frequency. Are they annoying?
If the engine is off you can hear them. I have a "stock (laugh)" 87 cabriolet. I can hear my engine more than the fans. I wish I could hear my stereo but can't find good speakers for the cabriolet's rear panels (hint).

Back to you question on the Duehl Kuehl closer to the door jam, the jam and rear inner interior panels cut down most of the sound. Frankly I think the stock front condenser fan is more noticeable.

Though we continue to re-explore and revise the Kuehl systems constantly, we keep what works. In the mean time we are working on another use for air and will keep you posted on this new product if something does not blow up.

[kuehl]

Originally posted by rusnak
Kuel: I haven't driven the rear condensor setup, I confess. But an honest question: if heat defeats the rear decklid condensor, and that temp environment is around 200F at the fan, then wouldn't the 600F at the cat be worse? True, airflow helps to direct heat away, but you have to stop or slow down at some point. And the rear fender condensor IS awfully close looking to that hot cat. Enough to make a person wonder, you know?

I remember reading some tech articles that pretty much concluded that the 964 condenser is superior, but the 993 is even better. Both required hacking and welding at least on par with adding a front condensor hole in the front trunk.

Has anyone added a 964 fan to the 3.0 and 3.2 fan hoop? Will it work? Those curved blades might move more air, and thus help the cooling and AC condensor.

Rusnik, it's Kuehl with an "h".
Heat does not defeat the rear deck lid condenser. Too much heat given off by the rear deck lid condenser defeats the air cooled pancaker's cooling system. In a perfect world, starting with the 964 the a/c's heat was removed from the engine cooling system by placing the condenser in the front fender (I would hafe loved to be in P's engineering meetings on that one to watch the cringes, cries, and clapping).

With regard to the cat/heat question, ask the question "how does it work".

Understand that the initial goal behind the Kuehl systems for the 911 was to increase the "condenser" capacity of the system, dispose of the heat outside of the engine, and make it easy to do. Frankly we achieved that while exploring the 911 ac system in the Mr. Ice Project. What we have today in product, or what has developed since then, are improvements on the initial idea.

Can you put a 964 or 993 (both alike in footprint) in the rear fender of a 911... not easily because the stack or combined thickness of the condenser and fan. Though I know of one "hacker" here in NJ that puts turbo condensers in the rear fender when he gets frustrated.

Can you put the 964/993 fan on Kuehl Condenser, doubtful (fan package is too thick).

Can you put a 964/993 condenser and fan package in the front fender of the 911, why yes and I've seen some jobs posted here that look OEM and then I've seen some hackers.

Which is easier? The Kuehl unit is easier to install.

Which is more affordable, hacking something or bolting something in and driving onward? Time is money, money is time. Most of our clients want a reliable product, they are not shopping for the least expensive method but rather a more logical (in total) approach.

[fintstone]

The Kuehl products are a first rate design and an elegant solution to the compromises inherent in the stock design. They are lightweight and mount with minimal modification to the P-car. They seem to be a logical upgrade to a marginal system (to deal with insufficient condenser capacity)...particularly where upgrades like a procooler/barrier hoses are already installed. or for areas where the ambient temps are excessive. Although they are not cheap..I believe them to be a good value considering design and workmanship...and worth the price There is no reason that a 911 cannot have operational A/C...heck, the cheapest econoboxes have good A/C...Why drive the coolest car on the road....and be so uncomfortable that you cannot enjoy it?

[Dennis Kalma]

Gotta confess that if I were not doing a complete frame up rebuild of my '89, I would be going with the Keuhl system, looks pretty well engineered and makes the best of a bad situation a/c wise on the early 911's.

Personally though, I am going to cut into the inner fender of my '89, similar to what the 964 had (basically take out the battery bulge to make room) and fit the 964 condenser set up. Why you ask...first because I can, second, I like the idea of getting the weight and heat away from the rear of the car. It is going to be a pain, it is silly and frankly, I really don't care as my love for Porsche's is 70% construction and 30% driving....

Having said that, the serpentine evaporator coil is on my list to buy, as is a lighter/smaller compressor. Only delay in this whole process is that this work and life thing gets in the way of Porsche's...


Dennis

[Jim Sims]

"I like the idea of getting the weight and heat away from the rear of the car."

The Kuehl fender system (complete - fans and everything) weighs a whopping 13 lbs; a triple pass deck lid condenser weighs about 6.5 lbs. A significant portion of the rearward A/C weight is in the compressor and mounting brackets. There's where (in the mounting brackets) we could use some carbon fiber composite construction instead of the usual non-functional "bling" stuff that is marketed.

I need to do a heat production calculation of the relative waste heat for the engine (non-exhaust gas heat losses) versus that dumped by the A/C condensers. It would interesting to see a relative comparison.

[fintstone]

Although I am certainly no A/C expert like Jim, it seems clear to me that 13 extra lbs on a street car are a small price for cold air. You could save more than that by switching to a Sanden compressor over one of the old "truck type" models.

The Kuehl products are well conceived and designed. Although I am an engineer by trade and with enough time and effort...could come up with my own design (like any aftermarket part) my free time is too rare...and then I would have to find the small parts, test...manufacture, etc. I could go back and design and build polybronze bearings, etc...but Chuck at Elephant has already done that for me. I would only try to do that if it were apparent that available parts were deficient.

There is no need to reinvent the wheel. There are several manufacturers (Kuehl, Rennair, Performance Aire, etc) that make nice replacement parts that are improved over original parts, and I would certainly use those to upgrade when I was replacing defective parts (procooler to replace receiver/dryer, upgraded evaporator, barrier hoses, compressor, etc) or doing a new install...but the Kuehl parts are really the only ones I have seen to attempt to significantly improve on the original system design...and they are designed to do so without butchering a bunch of pristine sheet metal. In fact, it seems to me that it would be one of the few significant A/C modifications that would not seem to be "mickey mouse" to the point where they might affect resale. In fact, I would consider the Griffiths parts to actually increase resale. They are a known entity and their mounting design is well thought-out. If I am using my 911 as a daily driver and my A/C goes out on a Monday in August when temps are 100+, I want to be able to call someone and get a new part shipped next day to install that weekend...not wait till I can visit a wrecking yard or try to figure out the previous owner's generic system. It is also easy to undo. If you were to sell your P-car and the prospective owner didn't appreciate working A/C or convert it to a track-only car...it would be easy to remove the parts and swap them into another car due to the clean/minimal install. This also comes into play as cost savings if you are paying an installer.

[scottb]

Originally posted by Dennis Kalma
Personally though, I am going to cut into the inner fender of my '89, similar to what the 964 had (basically take out the battery bulge to make room) and fit the 964 condenser set up. Why you ask...first because I can, second, I like the idea of getting the weight and heat away from the rear of the car.

Dennis: Rather than carve up your car, why not go with the set-up I installed (see picture earlier in the thread)? It has a fan on the back side of the condenser, and can be installed without cutting the sheet metal.

[Dennis Kalma]

I have seen your set up, and yes, agree it is easier, simpler, doesn't take all the work etc.

But, I just want it fitted in better, just as if the factory had actually done a good job on a condenser on the "old" 911....

My byline says it all....

Dennis

[rusnak]

flintstone: What kind of stuff do you design/ engineer? Maybe we can talk you into designing a better front condenser fan? Better evaporator fan? A better main engine fan setup? We gotta move air in these cars and no one else will do it.

[fintstone]

I am an electrical/electronic engineer, but I work with DoD (weapon systems). Personally, I want to see how well a system works with the best combination of currently available components and perfect installation before I would even consider tackling a new design. Kuehl (Griffiths) did a project a couple of years ago that sounded pretty darn good to me. It is described on his website.

[brcorp]

Rusnak,

A fan, either condenser or evaporator, isn't going to make a significant difference - maybe a couple of degrees but not much more. A fan that pushes more air over the evap may even hurt in terms of noise and heat absorption.

For my money the best solution is more condenser area, having a well maintained system and properly charged with R-12.

Tinting the windows also helps alot as the back window acts like a magnifying glass.

Flintstone,

Griffith's has the best set up if you want plug and play with no effort. As far as engineering a new there is not a wole lot of room to work with. Basically add more condenser area and/or redesign the evaporator.

ScottB,

What happened with you additional condenser project?

[scottb]

Originally posted by brcorp
ScottB,

What happened with you additional condenser project?

Bill:

Life got in the way. I'll probably live with it the way it is through the summer, and then in the winter do something. I'm debating whether to add an under-belly condenser or something like the Duehl Kuehl. I'm just not convinced that I want another condenser back by the cat.

Scott

[brcorp]

ScottB,

No dice, that's the same story you used last year.

The A/C cools good enough for the moment - not great but tolerable. I took the car out yesterday, temp was 104, and it was actually quite nice. I cheated as I started out with the car from the garage so it wasn't heat saturated. If I get in the car after it has been sitting out side for hours and the interior temp is +125, then it takes about 10 minutes for it to be OK in the car.

I’ve also thought about the underbelly and/or Duehl Kuehl but I hate to purge $100 worth of R-12.

I’ve also though about replacing all the condensers with parallel flow or serpentine type though I’m not sure I can justify the cost.

[scottb]

Originally posted by brcorp
ScottB,

No dice, that's the same story you used last year.

I’ve also thought about the underbelly and/or Duehl Kuehl but I hate to purge $100 worth of R-12.

At least I'm consistent!

Go to your local a/c shop and have them recover the R12 for you. Then do you modifications and have them recharge the system with your own R12.

[brcorp]

I thought about it but can't find anyone to do it for a reasonable price. I can get R-12 for about $24.00 a can and to recover the R-12 in the system and recharge is $140.00

[kuehl]

There is a "corner" gas station down the road. They have a sign up that says "AC Service, R134a $89.00". I thought about that... a 30 pounder three years ago was about $110.00 or $3.66 wholesale. Two years ago, when one of the R134a plants was shut down the price jumped to about $250.00 for 30 lbs or $8.33 wholesale. Today its back at $3.66 avg wholesale per pound. So if the avg car drove in there and they used 3lbs at the most, that would about $11.00 cost wholesale material cost. Give um a 3x markup to cover disposals, overheads, admin and profit and you are looking at $33.00 for the R134a. If they spent an hour on the car: evacuate, recharge and "corner station quicky" test,
add $75.00 cheap per hour. $33.00 + $75.00 would be $108.00 for the job. But they are charging $89.00, so maybe the material markup is less or the labor is less.... or they are going to short-cut the job (most likely). So I would not take any of my cars there.

I think the average cost in the NJ area is between $150.00 to $200.00 to do a "decent" job at evacuation, charge, and scratch and sniff, and a test drive for R134a in a 911.

I'd like to find a shop that could do the same with R12 for even $250.00 .... just a thought.

Take the $140.00 deal and run with it while the season is young!