This is a good summer time topic Does anyone know what is the minimum CFM GM engine fans are at? (V8s only, of course) I just bought a 3,000 cfm fan and, It let the truck overheat. I gained 4mpg though, so I would rather not go back to the almost 6lbs of mechanical fan robing horse power. I figure the stock fan, in full clutch-lock probably pulls 4,000 cfm... at least. so now its either back to stock; or buy another fan, put them together, and suck 6,000 cfm (and possibly small birds) through the front... thoughts?... I found it. needs to be a bare min of 5,000 cfm over 5,500 CFM if your towing..... I had no idea that much air needs to pass through the grill, condenser, and radiator, etc.