On 2 of my cars I use a 16" fan on the engine side of the radiator as a puller. The last one I got off eBay and I don't remember but I think it was like 2500-300cfm. They work well for our drag only cars. On my other car I had 2 10" fans mounted in front of the Radiator due to spacing issues. The car never would cool down right so I ended up moving stuff around and installed them on the backside of the radiator and made them pullers. Car cools down much better now. I have champion 3 core radiators in all the cars