Recommended Air Flow over the front A/C condenser
 

Well the title pretty much says it all.

Is there a Porsche spec that specifies the recommended amount of air (measured in CFM) that should flow over the front A/C condenser? I am ready to install that component and wanted to know what the Fellas in Stuttgart thought.

Thanks

It is not much, that is for sure. With the AC system running that fan does not produce a lot of volume. If you put your hand under the front bumper you can feel warm air sort of oozing out. Since I have 3 other condensers I don't figurer it does a lot on my car.

The factory tube and fin condenser does help a smidgen in stop and go traffic but quite a lot underway at a decent roadspeed.

The aftermarket ones seem to rely strickly on the low volume HIGH noise content of that front fan as every one of those appear to be designed to BLOCK airflow due to roadspeed.

How could this be? If the fan helps the factory how could the fan not help the aftermarket one.

I would think that the aftermarket would be as good as the stock. I really would also be interested in putting a better fan on those units. Seems like if you could get better airflow it would be Better than a spal fan on the deck...

Do you have a chin spoiler? Seems like that would also make a big difference in the amount of airflow.

The great contributor of unsubstantiated armchair thinking, with a big twist of spite, spews non-value adding hatred again.

What a joke this guy is. Why he is not sent to the island for harassment is beyond me.

I agree Bob. Pelican Must really not care about the continued assault on products they sell and endorse. Seems strange to me.

Within a small handful of posts we are down the rat hole again. The OP routinely is confused and disengages. The thread dies from being valuable once wwest posts and receives push back.

No benefit to discussing the original topic as continuity is gone.

It's disgusting.

I measured airflow with an anemometer and made some rough calculations. I've posted the numbers before if you want to search my username. What follows is strictly from memory so I may be off.

IIRC the flow from the factory set up is only around 320 CFM. The motor from a Carrera footwell blower is almost a straight drop in and will increase flow rate to 450 CFM. You have to fiddle with the wiring hook ups but the motor physically fits. Again from memory the condenser motor spins around 3k rpm and the footwell motor closer to 5k rpm. With a footwell motor installed noise increases significantly. Not enough to hear inside the car but everyone around you will know it's on.

The factory condenser fan actually blows just enough to create a circular flow pattern. Someone else here, posted a diagram. I didn't think of it but I did come up with a redneck test for it so I could demonstrate for my daughter. The fan is set up over one end of the condenser and the plate it sits on has a slight peak. Air flows down on the driver's side and up on the passenger's side.

Go the the bathroom and grab a single square of tissue. Turn your A/C on and key to the run position so the fan is blowing. Holding the square flat in your hand try to place it flat against the condenser cage on the D/S of the car. Can't be done. Now try the same thing on the P/S of the condenser. Airflow on the P/S of the condenser will pull and hold a tissue against the bottom of the cage.

As WWest noted 911 A/C works much better at speed that when stationary. What he continues to ignore is that front condenser airflow at speed is not front to back. It's top down. WWest denigrates the design of aftermarket front condensers while ignoring the evidence that they actually work better. When the car is at speed air is flowing under the car and past the condenser. The air flowing past the condenser is pulling air through the condenser. The flow at speed is still limited by the fact that any air flowing through the condenser must be sucked in through the small hole in the front of the tub. -J

ETA - I ran a footwell blower motor last summer. The extra airflow definitely helped prevent vent temps from climbing when the car was stationary (at a stop light,etc). I'm not sure that it did a lot at speed. I eventually pulled it and went back to a regular condenser blower motor. -J

Thanks JAR0023

I found the link.

http://forums.pelicanparts.com/porsche-911-technical-forum/427532-cfm-front-ac-condenser-fan-2.html

Thanks, Bob. I edited my post to correct flow numbers. It's not as big a jump in flow as I remembered to move to the footwell motor. -J

Good info. Guess we have another case where wwest is full of bs on which he has no proof other than his own dreamed up theory. Post your videos wwest. Just because the front condenser seems to do nothing at 70 degree ambient where you live doesn't mean it doesn't work at 95 degree ambients. Probably should just shut up so you don't continue to look foolish.

Insofar as the fan goes the aftermarket front lip condensers probably work better than factory, but since natural airflow arising from roadspeed is quite thoroughly BLOCKED then overall they are SNAKE OIL.

Most helpful A/C post I've seen here in a while; thank you JAR0023.

Followed by the most usless post in an AC thread.

Bob, have you not taken a good close look at the aftermarket front lip condensers? If not then you mostly certainly should.

Once you have would you please inform all of use just how those aftermarket front lip condensers take advantage of the HIGH LEVEL of cooling airflow at, say, 70 MPH.

What is the front to back airflow path?

But in stop and go would be more effective as a heat exchanger than the deck. At speed your spal on the deck does more harm than good as it blocks airflow. A better front condenser in stop and go would actually reduce engine temps. Think wwest think.

Have you thought about running the cabin heater blower, perhaps even automatically, either with a trinary pressure or thermal switch?

It's amazing how myopic one's view is when they are fueled by hatred.


At speed air pressure on the front of the car added to the blower fan creates a high pressure area above the condenser.

Airflow under the car creates a low pressure area under the condenser.

Airflow is top down. The faster you go the greater the airflow.


$hit, my 10 year old knows who Bernoulli is. -J

I don't profess to understand airflow. I'll leave that to guys that do.

You have a lot of value to add wwest. I'll stick to my single argument. That is, your grudge is disruptive to the overall integrity of this forum - specifically AC threads.

I do like it (a lot) when you beat on Lorenfb but he demonstrates behavior that is deserving of such. I ain't seeing that in the AC thread community as a rule.