I have a 69 Camaro street strip car. It has a 406 small block with a factory 3 core radiator right now. Believe it or not, it cools just fine with a factory non-clutch, high pitch 4 blade fan!

The ONLY reason I am going to an electric fan is to help with cool down between rounds.

That brings me to my question....how do you decide how much CFM you need? I see fans from 615 to 2600CFM! Any input is appreciated!

2600 is the lowest you should do. I run a 3200 spal fan on a small block and when it is hot it just makes it. The systems that work well are all dual fans in the 4000 CFM or greater region.

Ron