I'm running to 16" zirgo blu fans that are rated at 3500cfm's each and they work like a charm! I think the longest time I have heard them cut on was for about 1.5-2 min and I keep the temp at around 200 deg. winter time they never cut on (all the other cooling parts are stock)
watahyahknow is right! you have to wire them right. I have each fan on its own relay and fuse that then run to the main relay and fuse that is kicked on by a digital fan switch and he!! it has it own relay so with all that and the larger ga. wire if one fan was to go south on me the other would keep on working( I hope)!?