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A/C evaporator in the trunk...an option?
Some of us are installing or are in the process of upgrading the A/C.
A friend of mine installed a universal underdash evaporator unit in the trunk and routed the air to the dash outlets. It is an option and does not cost a fortune. I found this article on A/C for a 356 and it goes somewhat in that direction. What you think? 356 Porsche Air Conditioning |
You mean like a 964? Why not Singer did it too, well now they use a 964 chassis anyway so...
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Really I have not seen the 964 evaporator/blower arrangement. I thought it was about the same as the previous 911. Is it different?
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The 911/930 (evaporator and box) vs. the 964(C2,C4)/993 are two different worlds.
What do you want to achieve and in what model and year? |
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It will be something like this 356. http://derwhites356literature.com/356Pac2.jpg |
Waht you show there is basically what goes in the smugglers box in the 89 and older 911. With the 964 Porsche put the evaporator with 2 fans in the bulkhead area. It is a real improvement in the amount of air it can move. In my 73 the fan is almost always on high, on my 964 it's about halfway. The 964 also took the condensor off above the engine and put it in the left front fender with a fan. Mr. Kuehl (above) is really the expert on upgrading the 911 air conditioning sytems.
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I can't say for the moment that you are pointing out a lower cost alternate to what has been done in the past 45 years (between Porsche, Behr's alliance, Bruce Anderson's work, the host's notes, Scotty, Performance Air, Renn, Retro, Griffiths..aka Kuehl, or others).
Your concept, though not new, has been tried but this does not mean there is a closed door on the idea. We all enjoy 'thinking out of the box' (no pun intended). The issue for some is keeping things 'looking original', for others its cost, simplicity, reliability and finally performance. A better evaporator vs. stock will help cool down the car. A better blower motor vs. stock will help cool down the car. But you have to also consider the other side, condenser, in your concept if you want to minimally match the system together (we'll ignore the pump and vents for the moment). Getting back to your idea you'll have to take into account, in no order for the moment: A) a minimum size blower motor; rpm's and torque, efficiency and amps required. B) blower cfm; the wheel size, design and rpm C) evaporator coil size; design type (plate and fin, tube and fin, serpentine) and BTU/Hr per sq mm. D) Cockpit volume, area of glass, btu exchange. Once you find something that matches your requirements above you'll have to "hack" it into the front trunk working in, through or around all the 'stuff' there and re-engineering that 'stuff's' functions. I'd say if your trying to install an evaporator/blower system in a car that never had factory air ... that effort would be more rewarding. You could either approach the project blindly so your not plagued with the bias mentioned or research what has been done, what works and what does not work and save yourself a lot of time and materials. Personally I prefer all the front trunk space I can afford. In my car the golf clubs sit in the passenger seat, the travel bags in the back, the trunk is reserved for my case of Becks and case of golf balls, each relies on the other. |
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That can be easily corrected via mounting 2 relatively inexpensive (<$50, Ebay) 12 volt radiator cooling fans to move air continuously through, DOWN ("sucking") through, the engine lid condensor even with the engine at idle. Use a relay to run the fans any time the compressor clutch is engaged. Not a bad idea to run the fans in low speed, series, even when the compressor clutch is not engaged by the A/C is on. |
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IMSO the primary short-coming is the lack of refrigerant condensing/cooling capacity. Even Kuehl agreed with this in one of his posts. If you happen to have deep enough pockets there is no question that the first move you should make is to add another condensor, or one with more capacity.... AND efficiency. I have little doubt that the engine lid condensor has well enough base capacity, but the sometimes low RPM of the engine fan results in a lack of consistent efficiency. Adding 2 electric radiator cooling fans at the point of most efficient heat transfer, the HOT, inlet end of the engine lid condensor does the trick. I don't know, can't say, about the issue of dumping extra heat into the engine as a result...but I strongly suspect it would result in better engine cooling rather than otherwise. And let's not forget about the radiant heating effects from the engine, HOT engine, that will constantly adversely affect the condensor efficiency, moreos at idle. |
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Let's assume, for the moment, that the system is well able to sustain the evaporator at the point of almost freezing up, the cabin temperature is 110F (been setting out in the HOT sun all day. Which would you say will cool the car down quickest, move the most BTU's/time, to a comfortable level, 75F...?
1. Highest blower speed. 2. Medium Blower speed. 3. Lowest Blower speed. Hint. How long must you leave a warm glass of milk in the fridge before it declines to the temperature level inside the fridge? Hint #2 : Which speed will most rapidly dehumidify the cabin atmosphere? IMMHO HIGH blower speeds are desireable ONLY to most rapidly move the previously HEATED, HOT cabin atmosphere OUT. Regretably our air-cooled Porsche's have NO "fresh" airflow ability. Now there's a product idea that might well sell very well in Houston....an automatic exhaust fan that only operates as long as the outgoing, exhausting, air temperature is equal to the actual OAT. Perhaps a few minutes beyond in order to help bring down, initially, the cabin surface's elevated temperatures. |
The topic is an evaporator/blower all-in-one unit?
But you have to also consider the other side, condenser, in your concept if you want to minimally match the system together Did I really say that? "Kuehl: Condensing capability should always be first on your list" (hold on on move it to the top). "IMSO the primary short-coming is the lack of refrigerant condensing/cooling capacity. Even Kuehl agreed with this in one of his posts. (oh, sugar I did say that, guess we got read all of the posts all over again) " |
Saint Black,
We beseech you to grant us the wisdom to know heat from temperature and be sensible about things latent. :D |
ahhhh.... yeah, AMEN, brother
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I recently found a unit designed for ambulances with 28k BTUs but am not sure it fits. Will keep searching. I have two questions for the experts: Factory BTUs? Factory blower CFMs? Thanks |
Grabbing the milk and cookies to watch this one...
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http:// [IMG]http://i204.photobucket...-4-400x300.jpg[/IMG]Just found this article in ferdinandmagazine.com that goes in the subject idea (Tried to upload a photo from my mobile but can not see it, sorry if it doesn't show)
http://pocket.co/s8xcY http://ferdinandmagazine.com/ http:// http://i204.photobucket.com/...-4-400x300.jpg |
One thing you need to remember is that before I would go the route that the link above shows, I would get a good parallel flow front and rear condensor long before cutting up the front of my car like this.
The single parallel flow condensor shown in the photo on the link is the same size if not smaller than what is on the 911 in its stock configuration. Why go to all this work to end up with a smaller condensor? Only plus I can see is getting more air-flow through this setup... That would help but only if you have a big enough condensor(s) to cool the gas in the system to where the evap unit can work with it. IMHO the condensor shown in the photo needs to be much bigger, or be paired with an additional one on the car. As is its too small... |
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Scotts Independant used to mount a very large condensor under the seat area with no fans. I've see several cars with this kit around here and the a/c works VERY well. I think it was about 48 in wide and 18 long. Amazingly it survives quite well there as long as you do no rallying.
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RS,
This condensor was marketed under the Performance Aire brand. I used to have one and finally sold it this spring to put a parallel flow condensor in. |
A/c
balleta- did you get the trunk A/C installed. I have the same interest. Let me know how it turned out.
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However, you need the knee room or toe room, much easier to do in a 356 or 914. Naturally, and then you still need the drier, compressor, comp mount, barrier hoses, condenser(s), clamps, wire harness, etc. |
Knee space is not interrupted since the unit is in the trunk not inside the car. That was about the route of the 964s blower sytem.
Sent from my GT-I9100 using Tapatalk 2 |
"'all-in-one" units simply bolt under the dash, hence 'knee room',
you'll never fit a 964/993 entire box in the 911 trunk... easily |
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All in one units "usually" are mounted under dash but in this application it goes in the trunk. Then outputs goes to the vents via conducts. Recirculation is provided the same way, one hose at each side of the blowers goes to holes from the cabin. Cabin air flow is improved and with an under the front fender condenser, barrier hoses, etc. the package is complete.
Sent from my GT-I9100 using Tapatalk 2 |
Oh, I have seen 'in the trunk' evap boxes with blowers; self contained.
Even worked on a few, some were unique and another I recall simply did not do the job. You can build one too if you want to. They are not an upgrade to a stock system. You can purchase a used stock evap box system and air tubes and fittings, and just drop it in the smugglers box alike a factory set up. In either case of a 'in the trunk unit' vs dropping in a factory style unit, you need wiring, controls and vents. If you have an earlier narrow body car you don't have much room for vents in the dash other than one above the radio. And for factory ac units through 1985 you simply did not have enough vents... Tri-Kuehl Vents Years ago we designed a system for cars that did not have air. Spent 3 months on trying to perfect the 'perfect' vent arrangement. In the end the original Behr Knee Pad system was the best design, in terms of vent location, number of necessary vents and control location. The cost to duplicate that unit (molds, minimum number of shots off the molds, etc) is not as affordable as simply finding a good used Behr knee pad vent and fixing it up, and locating a good used pre 86 Behr evap box and dropping it in the Smugglers box well and cutting the necessary holes. There was a company that marketed an 'alike' Behr knee pad panel but the quality and design is not as good as a 'good old original'. |
I already have a Behr knee pad vent unit. Do you know how compares the "original" smugglers box unit with improved fan motor and a universal under dash unit in terms of CFMs?
Sent from my GT-I9100 using Tapatalk 2 |
Use an anemometer
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Blasphemy & Sacrilege to the promoters of 911 serpentine technology condenser heat exchangers LoL Joe I thought you posted several times here you went with Griffiths serpentine condensers! Hmm has he seen the light??? |
balleta
before you go hacking up any of the body on a 911, you need to think very carefully how it is going to de-value the 911 Also understand that the OEM evaporator with a few smugglers box and evaporator tips and tricks done to it, i.e. availible here in the 911 Pelican tech threads etc; can be made to work pretty good with only a little TLC. Remember That the most imporant problem on an early model 911 is its condensers for making a cold a/c, maybe this will help you think a bit differently http://forums.pelicanparts.com/porsche-911-technical-forum/674449-ice-cold-c-30s-f.html |
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