Thinking about running a thermo fan on my 21 stud flathead, I have a 12 volt alternator and I'd like to remove the fan off it before it buggers the bearing. And of course have better cooling. Question being; how big does the fan need to be and what sort of CFM would be required. Im looking at a 16" job that has a 220 watt motor with a controller that cuts in a 185 and comes off at 175. I have talked with the guy selling them had said that it will do over 2000 CFM.. Also said be sus about the ones claiming high CFM its mainly BS ! SO is over 2000 CFM enough??