A/C evaporator in the trunk...an option?

[balleta]

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

[RSTarga]

You mean like a 964? Why not Singer did it too, well now they use a 964 chassis anyway so...

[balleta]

Really I have not seen the 964 evaporator/blower arrangement. I thought it was about the same as the previous 911. Is it different?

[kuehl]

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?

[balleta]

Originally Posted by kuehl

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?

I'm trying to point out a lower cost alternative to the high cost involved in setting up or upgrading the A/C in a 911. In my case a 1978 SC. An universal evaporator/blower assembly with enough output routed to the current factory outlets or in my case to underdash outlets. I'm aware that some trunk space will be sacrificed but anyway we don't use most of that space.
It will be something like this 356.

[RSTarga]

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.

[kuehl]

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.

[wwest]

Originally Posted by balleta

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

The factory A/C system is more than adequate in a climate such as we have here in Seattle. The only short-coming the system has in hotter climates is the lack of a consistently high level of airflow through the condensor mounted on the engine lid.

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.

[wwest]

Originally Posted by balleta

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

The very first thing you should do, MUST do, is determine the actual short-coming(s) of the factory system. In that route do not forget to pay close attention to Porsche's own design upgrade once the initial design proved to be inadequate.

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.

[wwest]

Originally Posted by kuehl

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.

Only if the LIQUID refrigerant supply is already sufficient at keeping the evaporator very close to the maximum HEAT transfer capability, <35F You can't "take" BTUs from the evaporator that the upstream system cannot supply.

A better blower motor vs. stock will help cool down the car.

Again, ONLY if the evaporator can be kept below 35F. BTUs?

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.

Kuehl: Condensing capability should always be first on your list.

[wwest]

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.

[kuehl]

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) "

[Jim Sims]

Saint Black,

We beseech you to grant us the wisdom to know heat from temperature and be sensible about things latent.

[kuehl]

ahhhh.... yeah, AMEN, brother

[balleta]

Originally Posted by kuehl

The topic is an evaporator/blower all-in-one unit?

Sorry for the late answer but, yes evap & blower in one unit.
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

[Joeaksa]

Grabbing the milk and cookies to watch this one...

[balleta]

[/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/

[Joeaksa]

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...

[Neel]

Originally Posted by Joeaksa

Grabbing the milk and cookies to watch this one...

+1 Except Crown and Coke for me....... Probably several..

[balleta]

Originally Posted by Joeaksa

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...

I agree about the condensors. And I think that that kind of cutting off the front is unnecesary. BTW I remember a 1973 VW Superbeetle I had that just had an underside front condensor with a fan. It came "factory" like that. No rear condesor. And it worked real good here in the Caribbean weather. I have checked other VWs and have not seen one with an over the engine condensor.