Boy some of these questions I can't answer. I'm kinda a shade tree mechanic. The tube sensor is about three inches long and about 1/8 diameter. It was sent with a plastic gizmo you push between the fins and hold it against the core on the engine side of the Radiator. The fact that this might not give you a accurate reading is not important, you adjust the switch to match the temp you want them to come on. I don't know the CFM of the fans, They are dual fans approximately 12inches that I picked up at the local salvage yard for 5 bucks. I am running no relay at this time. a Very short lead from the voltage regulator to the temp control switch. They just come on automaticly at 185 degrees. T he only annoying part of this is they cycle on and off for 20min after I shut down. The fans have a inline fuse I installed that is rated at 20amp and I am not blowing it. so the draw must be less than that. Sorry I can't give you more info.
