Griffith's fender condenser dimensions

[scottb]

Charlie Griffiths knows his stuff when it comes to Porsche AC. Period. I'm sure he has tons of test data supporting the effectiveness of the rear fender condesner. My gut, however, said to me that having a condenser near the catalytic converter was putting the condenser in a hot environment, which has to reduce its effectiveness. The installation in the right left fender was probably more difficult due to the relcation of the washer and vapor bottles, but in the long run I'm finding it VERY effective.

[kuehl]

930slant,

Air movement plays a big roll in feeling cool. With the pre 86 models: our center and side kuehl vents make a big difference, while on 86+ the larger stock side vents and adding the center kuehl vent makes it comfortable.

We had explored increasing the fan output. The foot print of the Behr evaporator box limits you to fan size and type of motor. We are still playing with the motor however we also get calls from owners who want quieter air systems.

When set up and charged properly the single kuehl and optional duehl kuehl work well. On the other hand we get many calls from 964/993 owners who want to improve upon the single LH front mounted OEM system.

I'm still on first cup of coffee so when I figure out where I am this mornin we'll post some more .

griff

[philipguziec]

The name of the game is not vent temps, but total heat transfer. Think of it as CFM flow times the difference between outlet temp and inlet temp. So, if you've got 32 degree vent temps, then increase your flow across the evaporator and you'll get more cooling (delta temp times flow) out of the system and more quickly lower the cabin temps, or keep the cabin temps at a lower level in the hot sun. If your vent temps are running at 32, and you increase the flow, you will get more capacity out of the system because the system has to shut down to keep from icing the evaporator. Also, bigger air vent openings will lower the noise associated with the flow. As an experiment, close all your vents and then open them one by one, listening to the system get quieter. I've been thinking about using a hole saw on my center vent hole and sticking a big directable spal vent in there to increase outlet area to reduce airflow noise, and also increase flow by making the system less restrictive.

[kuehl]

Ahhhh, Yes, and No.
Yes, btu or heat transfer,
No on max. cfm.
Though the stock Behr evaporator motor and fans dumps out tons of cfm, by the time it gets through the system you have a pressure drop.

Though there is always a way to skin a cat, from an economical standpoint the current vehicle layout limits you to only doing so much before you end up with a total hack job. For instance, not easy to open the small stock side vents found on pre 83 cars, the sheetmetal just won't allow you to, unless you hack major. So with the side mounted Kuehl vents you can easily drop the OE vent tubing into the Kuehl vents.

Almost the same story on the lower bow tie floor vent. Remove the bow tie deflector and you get more volume quickly into the cabin, however its not directional air flow, you need a vent with a louver to direct the air flow, hence the Kuehl center vent. Though you, once again, get a pressure drop, from an economics standpoint the quick mounting vent works wonders.
You could take it a step further and hack a holesaw adjacent to the stock air outlet hole/plenum here , however now you are hacking and you will lose air flow from the side vents.

Bottom line, the dashboard was never layed out to support ac, you can only improvise on what you have economically.

But, good thoughts to chew on.

[kuehl]

correction, need second cup of coffee:

"vents found on pre 83 cars" sb found on pre 86 cars.

[indigowhale]

This is a great thread! I am about to embark on the same venture with the AC-8041
from http://www.mtgparts.com/merchant2/merchant.mvc?Screen=PROD&Product_Code=AC-8041&Category_Code=ACH as advised by Phil. I will try to mount mine in front of the rear wheel as I don't want to muck it up with road splash and the cat heat is of real concern.

Now a few AC newbie questions:

1. Where do you get the hosing and how do you make sure to get the correct fittings?

2. A new hose will run from the deck lid condenser to the rear fender well new auxiliary condenser and then to the receiver drier; are the fittings on the unit pictured above (AC-8041) and the stock condenser and receiver/drier the same kind?

3. What are the "barrier" hoses?

4. How do I know to get the correct "O" ring seals and where?

5. I plan to replace the following: Rec/Drier, Expansion valve, hoses between rear condenser and rec/drier, install new condenser + fan, and 134a. Also plan to get a vent or two. Is this enough?

6. Does anyone know of a reasonable priced vacuum pump that will not fall apart after one use?

With 134 on a 92 F day, my vents were only blowing at 78 F. This is with the system fully charged with 134a and all stock parts. With the bowtie vents, I am guessing I need to get below 60 F to make it work.

Thanks to all for posting this info, I will put it to use and post pictures and results.

[niner11]

Anybody have progress to report. Its so hot this time of year that I'm affraid to do anything more than put 134 in my leaking stock hoses.


I promise full pictures of my 964 condenser and procooler install when I get there.

Kind of surprised that my stock SC (with an updated compresser) can put out vent temps of 40 to 44 degrees when I'm moving and not sitting in traffic.

[niner11]

Here is the Yearwood vent that I read about and finally tracked down.



I found the rest of the pieces on the wet/dry vac isle at home depot for about 10 bucks. The vent itself was 12.00 plus shipping from yearwood. Yearwood HOT 24 1000 was the number it was listed under.

For what its worth I think Griffiths vent isn't too far out of line (price wise) for the quality of air improvement that it makes.
I had to spend close to 30 bucks and cut my hand with a razor blade to get something that isn't quite as stock looking as their Kuel vent

[kuehl]

niner11,

If your time is valuable, YES the pre-assembled Kuehl Vent is worth the value; by the time you add up making phone calls to order parts, road travel to pick up odd's and ends, layout time, fabrication time, etc,,,,, the TIME alone is more than the cost of our ready to install-bolt-on Kuehl Vent solution.

by the way, nice job on your design.

Kuehl

[philipguziec]

Ahhhh, Yes, and No.
Yes, btu or heat transfer,
No on max. cfm.
Though the stock Behr evaporator motor and fans dumps out tons of cfm, by the time it gets through the system you have a pressure drop.


Hmmm... I'm not sure which engineering school you went to but, at reasonable temperature and pressure differences, heat transfer is equal to mass flow times temperature change. CFM times (vent temp minus inlet temp).

To get heat transfer out of the human body, you want the low temp air directed at the body, but I doubt this is a big determinant for auto AC. Nothing can beat a low ambient in car temp with low humidity for comfort, and the way to get that is heat transfer (volume over the evap and an evap close to freezing without frosting).

Now, if you want to get into the psychometrics of human heat transfer (how cool you feel), you have to combine the perception of cooling from airflow over the body, as well as the lowered humidity reducing the persperation that remains on the body, allowing the cooling from evaporation of perspiration to work it's magic, as well as feeling cooler because you don't feel sticky.

At the end of the day, the more volume you move and the greater the temp drop the better. If you can get vent outlet temps near the frosting point of the evaporator, then push more CFM, and bigger outlet areas will improve the noise. Then, if you are getting outlet temperatures rising, increase the heat rejection capacity (add fans to the condensors, add condensers, etc.) and coefficient of performance (use a heat exchanger like the pro-cooler to hook the hot side and cold side together by the evaporator, use a better refrigerant).


Though there is always a way to skin a cat, from an economical standpoint the current vehicle layout limits you to only doing so much before you end up with a total hack job. For instance, not easy to open the small stock side vents found on pre 83 cars, the sheetmetal just won't allow you to, unless you hack major. So with the side mounted Kuehl vents you can easily drop the OE vent tubing into the Kuehl vents.

Almost the same story on the lower bow tie floor vent. Remove the bow tie deflector and you get more volume quickly into the cabin, however its not directional air flow, you need a vent with a louver to direct the air flow, hence the Kuehl center vent. Though you, once again, get a pressure drop, from an economics standpoint the quick mounting vent works wonders.
You could take it a step further and hack a holesaw adjacent to the stock air outlet hole/plenum here , however now you are hacking and you will lose air flow from the side vents.


No problem. A holesaw and a spal vent will look quite nice, you can close the spal vent, and I'll play with adding an inline fan to increase volume through the evaporator.


Bottom line, the dashboard was never layed out to support ac, you can only improvise on what you have economically.


Dash layout isn't a big driver. My mom used to drive me around in the 70s in a 56 t-bird that my grandfather retrofitted with an AC system using a kit from that era. That retrofit consisted of an evaporator unit under the dash with a fan blowing through it. No directional flow. The thing would give you hypothermia. The key is volume through the evaporator, keeping the evaporator cold, which means keeping the heat flowing out of the condensers with fans, and keeping the system performance up.

[kuehl]

philipguziec,
OK Phil,
Let's see what you got when you get done.

[philipguziec]

Sure, I'll post results, but I'd sure like to hear where I'm violating the laws of physics.

[niner11]

We need less theory here and more worky, worky,

[Seeeu911]

Ok, some worky..
I just can’t swing the sweet rear fender condenser setup. I have to do a roll my own solution. That’s kind of why I have the Pcar anyway; the fun for me is in the doing.

I ordered the AC-8041 unit and figured when it came if it was cheesy or too much a PITA I would suck it up and spend the big$$.
I was pleasantly surprised at the quality of the unit. I had called and talked to MTG tech support/Shawn? And made sure of the dimensions.
I read every thread and looked at lots of web sites and others experiences. This board is an amazing treasure trove of info.

Brcorp and his install were extremely helpful.
The install was really straightforward. Test fit, fab brackets, look at various mount/isolators measure hoses, plumb wiring.

Costs total: Condenser $119.00
Hoses $55.
$33
Brackets, relay, clamps etc beer $ $40.00
Total: $250 or so.


Amazon Hose is making 2 new hoses for me. One is 16 feet long, front condenser to the fender unit, the other from the rear condenser to the fender condenser.




I had received a new rear condenser unit. A Parallel design. Very robust. A very very tight fir but it’s in...Barely…



I will install hoses tonight and then be ready for a recharge with 134 this week.

Oh, also adjusted the expansion valve to 8 ¼ turns out.

[Seeeu911]

So to recap, I will have
* Procooler
* New barrier hoses
* New compressor
* New serpentine evaporator
* New rear decklid condenser parallel design
* New Rear fender mounted condenser Tube/Fin with fan
* Yearwood vent

I am shooting for temps in the high 30-low 40’s with R134a

[niner11]

I agree it is more fun to do it yourself. Good luck with the install.

[kuehl]

Gee, I dont' know guys, Seeeu911 says he got beers included in the $40.00 ? You see any cold ones or discards in those pictures.
I think he's holding out on us.

P.S. looks like the bike needs new sneakers.

[brcorp]

Seeeu911: Great job on the install, I'm one up one you though as I polished my aluminum brackets.

Don't keep us in suspense too long, post some results.

[scottb]

Seeu911: What's the story on the rear decklid condenser? Dimensions? Cost? Mounting issues? Etc.

[Seeeu911]

There are several places on the web you can find Universal Parallel Flow Condensers ..."Parallel Flow condensers are approximately 1/3rd more efficient than a standard OEM Tube & Fin condenser. When converting from R12 to R134a using a Parallel Flow model condenser greatly improves performance. Parallel Flow condensers can also be used with R12 and alternative refrigerants.

It should be noted that a Parallel Flow condenser is not the same as a R134a compatible condenser. Dual pass and 6mm R134a compatible condensers though better than a standard Tube & Fin condenser do not perform as well as the TRUE Parallel Flow models we have tested....." from ACKITS.COM

this particular one is a pre production prototype not yet generally avail for sale. I'll post more info as it comes to me. At least one other person here had this installed in his local area as well.

It is aluminum and unique in that it has a curve to fit 911 decklids. The install was easy once I got the idea of where the brackets were supposed to go. I had them in the wrong place at first. Closed there is only about 1/4 inch clearance front and rear..almost needed the astroglide