how much air?...

[nick sparrow]

I was wanting to know how much air in cmf a standard type 4 air cooling system delivers, does this amount vary from idle to max revs? And if so how much?

How does this compare to say a Porsche 911 fan set up (cmf), again does this vary over the range?

How much (cmf) does say a standard 2000cc engine need and how much would be too much?

Any help on these questions would be really great



Thanks in advance


nick sparrow

[Bulley412]

I was wanting to know how much air in cmf a standard type 4 air cooling system delivers, does this amount vary from idle to max revs? And if so how much? --- nick sparrow

Check with Jake Raby of Aircooled Technoolgies, or go to something like the MIT website. The formula for output of a squirrle-cage fan is pretty simple, but I don't recall it. I DO recall that the 1700-2000cc VW fan maxxes output at 4,000 rpm, and the standard cooling system has VAST overcapacity. The same cooling system reliably cools the Vanagon Westfalia, which fully loaded is 5,800 lbs, and eaily climbs mountains, etc. (I have one). The output naturally varies by engine speed, but so does the waste heat of the engine. It makes sense on an aircooled car to take steps to boost the revs when under load, such as shifting to third or to second when climbing speed inclines, and keeping it at 3/4 throttle rather than flooring it in fourth.

How does this compare to say a Porsche 911 fan set up (cmf), again does this vary over the range? --- nick sparrow

The Porsche fans (13 blade, 11 blade, etc) are designed for a much larger motor, and fairly universally cause overcooling in Type 4s.

How much (cmf) does say a standard 2000cc engine need and how much would be too much? --- nick sparrow

The factory cooling system (WITH ALL OF ITS PARTS INSTALLED) is pretty close to the best you can do. It can be aided by an additional oil cooler (outside the engine compartment or cooling air stream). Further, VW prescribed 1.5mm V-shaped notches in the connecting rod big-end boss to serve as an oil squirter to help the oil collect more waste heat from the piston. The combination of a thermostatically-controled oil cooler, these notches, and a cylinder-head-temperature gauge would cure all of your overheat worry far better than a 911 fan.

Take care, gmb


--- nick sparrow[/quote]