Quote Originally Posted by jerry clayton View Post
crank driven fans aren't fast enough at idle and too much above cruise speed.
Use a steel 18", 7-blade fan with 2 1/4" to 2 1/2" pitch with a thermostatically-controlled fan clutch and full shroud. In my opinion, that's about as good as it's going to get. Lay the fan down on your bench and measure from the bench to the fan blade leading edge to find the pitch. If you really want to move some air, use a steel fan from an Oldsmobile diesel (1978 to 1985). You should be able to find them in old boneyards. (3 inch pitch).

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