Electric fan switch

[bdepedro]

I'm installing a 24" alum radiator w/ twin 12" electric fans in my '70 stang w/ a modified 289. I'm trying to figure out the best temp switch to install. I notice that Painless and others seem to use a 185 on and 170 off switch but a guy in our local club who was a Ford engineer says to use a switch that is on at 215 and off at 200. I've also been told that I would get better performance w/ engine temps in the 190s. I believe I have a 195 thermostat in the car now. I want to keep the engine cool so the higher temps make me a bit nervous but also want it run at optimum temps. Can anyone suggest the best switch range and explain why? Thanks again guys!!

 

[blown65]

Why would you get better performance with the engine at 215? Go to the drags and race your car at 120 degrees, then make some runs at 200 and tell me how much you slow down. I go from 10.30's to high 40's when I make fast turn arounds just because the engine went from 120 to 160. Obviously you dont wanna run that cool on the street for wear issues, but I would stick with the 180 setup.

I have a fan switch on mine for street driving set around 170 to kick the fan on, and then I just run straight to ground when at the strip to stay as cool as possible.

Dont ask me, call up Joe Sherman sometime and he will tell ya how much you lose on the dyno.

 

[2+2GT]

Ford engines were designed with an optimum coolant temperature of 190°. Maybe circumstances have changed but I'd have to see a compelling reason to over-ride the specifications of the men who designed these engines. I used to know one of them, and he was smarter than me. And I have a Masters' Degree.

 

[bdepedro]

Thanks for the input guys. Just ordered a 185 on/ 170 off from Jegs. I'm also going to T off the switch line to a toggle switch that I can ground in case the temp switch ever fails. I'm also going to put a toggle switch in the low amp power supply to the relay so that I can turn the fan off if I want after the ignition is off for any reason. Thanks again for confirming my thoughts on this!