924Board.org

[Cbass]

Same principle as a regular intercooler. Air goes in one end, runs through, exits through other end.

The difference is that the air/water IC has a water jacket around the outside. If you know what you are doing when it comes to fabrication, you can build a water jacket around the IC. Just make sure it doesn't have any leaks.

[Cbass]

Same principle as a regular intercooler. Air goes in one end, runs through, exits through other end.

The difference is that the air/water IC has a water jacket around the outside. If you know what you are doing when it comes to fabrication, you can build a water jacket around the IC. Just make sure it doesn't have any leaks.

The big advantage is that with an air/air, there are three limitations on cooling. 1 is the ambient air temperature, 2 is airflow over the IC, and the third is the size of the IC.

With an air to water, the charge is cooled so much quicker and completely, that you can reduce the size of the IC. You also do not have to place it in an air flow.

Some air/water ICs have a secondary cooler to cool the water. I prefer the method of cooling it through the primary coolant system, piped into the radiator.

You just have to have a good radiator, to handle the extra load, which isn't much. If your radiator is limping on its last broken legs, you might push it over the edge.

[numbers]

The problem with using the radiator for cooling the water, is that radiator coolant is in the 160 to 180 degree range. To get the most benefit from an air/water set up you need to get the water under 100 degrees. i have an air/water design all laid out for the 931, but haven't gotten around to learning to weld aluminum so I can put it together. Another project for this summer.

[Cbass]

Yeah, the advantage to the radiator design is a low weight. You need to have a really efficient big radiator, to get your coolant temp as low as possible.

Or you could just run the IC on an independant coolant supply, but then you need another cooler. At that point, consider how much boost you're going to be running, and will you need that much cooling.

[Joes924]

Did not Pete Holiet,(think its spelled wrong)
port & polish a 931 head.

[Peter_in_AU]

the downside of a water/air intercooler is the weight and complexity when compared to an air/air. Comes down to; air/air is easier and lighter, water/air is harder, heavier but probably more thermally stable.

Have a read of http://www.autospeed.com/A_0084/P_1/article.html - the info of water/air is in part 2.

[wdb]

that article didnt mention what I think is a cheap and readily available heat exchanger for the intake side of the water/air intercooler. the heat exch. air cooled VW"s use to collect exhaust heat to provide cabin heat should be up to the task, and if they are not they are cheap(used), so if necessary, you can use two. in series will provide better cooling or parrallel will provide more airflow. I have never seen one upclose so I cant be sure it will work. for a location for the water cooling exchanger, maybe you could cut the sheet metal between the tail lights, where the porsche lense is and lay 2-3 cheap chevy heater cores(used) at 45 degrees to the airflow and install naca ducts or small scoops in the quater panels similar to the old mustangs to provide the airflow ,cheap plumbing vent pipe can be used to connect the ducts to the box containg the heater cores, or if you want it to be tight against the interior you can use three 2' pieces of pvc, or make your own ducting. a small electric fan might be needed to maintain airflow over the heater cores when your not moving. 1" pvc plumbing tubing can handle 200 degree water, 50 PSI and is cheap, so it can be used to carry the water to and fro, there is even insulation available to keep the cooled water cool.

[Cbass]

Yeah, PVC can handle 50 lbs at room temp, start your car up on a freezing day and see how much it can take

Tell me more about this VW heat exchange idea...

The fact of the matter is, an air/air cooler is good enough for most racing, and any street driving. If you have bonneville speed car, you might want an air/water, because you will be at peak boost for a long time. If you really need more cooling, go to a bigger air/air, or two small ones.

[wdb]

a 2L seven up bottle can take 150 psi, I'm sure pvc can handle 250 easy, a little anti freeze in the cold wouldnt hurt.

[Cbass]

PVC is great stuff, but it shatters very easily, especially when cold. My advice is to use ABS, you can abuse ABS and it'll just come back for more.

If you're looking at a scenario where it might get hit by a stone, jarred by impacted, or be exposed to rapid temperature changes, PVC is much more likely to break than ABS.