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Electric fan temp question.

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Posted (edited)

Sorry for the repeat guys but I can't find the post that had this discussion. 

I'm using a 180 stat along with dual electric fans. I'm also using my sniper to control on and off temps. 

What temps would you set them for based on the 180 stat? Would you have both come on at the same time? If staggered what would the suggested temps be?


Edited by 73' mach 1


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I have dual electric fans on mine and the same 180 stat, and what I have things set for in my sniper is that fan 1 comes on at 185 off at 180, and fan 2 comes on at 190 off at 185. It hasnt been super hot here yet, but usually only the first fan runs with the second one coming on every once in a while. 

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Posted (edited)

I would say this really depends on where its taking the temperature and how well the fans work.  Did they have any suggestions for you in the paperwork that came with your sniper?

If you have a temperature probe that's measuring the water temp in the engine, right at the thermostat, that's great for telling you how hot your engine is.  But you know your thermostat will be opening at 180F and that water going to the radiator and then the thermostat closing.  So now you have water closed up in the radiator, hopefully getting cooled down a bit, and then waiting to be pumped back into the motor when its needed.  Using the water temp in the intake to control the cooling fans has a big drawback in that the water is separated.  As the water in the radiator is cooling down, the water in your intake manifold is getting hotter.

Some people like to add a probe to the upper radiator hose, right when the hot water is coming in.  The idea there is that the fans kick on as soon as there's water that needs to be cooled down.  Downside is that your fans will be kicked on a lot more often.  Even if you're doing 80mph down the freeway, hot water will be triggering the fans to come on.

Some people like to take the temperature at the bottom radiator hose.  Right before the water is going into the engine.  Reason being, you have a better idea of the actual temperature of the "cold" water as its going into the motor.  But by this time, its really too late to do anything about it.  You can't cool the water much more after you measured it, because its already leaving the radiator and back to the engine.  Many factory cars these days use the temperature at the lower radiator hose to control the fans.  


Personally, I think the most important part is the operating temperature of the engine.  What you really care about is that its running at 195F or whatever number you decide.  You can arrive at that same 195F engine temp using a 160F or a 180F temp trigger for your fans, all just depending on where you were measuring the temperature.  And what works well in your car would be different that what works in mine, because we could have different radiators and different fans.

As far as my numbers, I'm running an aluminum radiator with dual 11" fans, rated for 1924 CFM total. 14lb radiator cap. 180 degree thermostat, on a mildly hopped up 351w.  I stuck my temp probe dead center of the radiator.  That way if I'm driving down the highway, the water has a chance to start cooling off without the fans and they won't come on if they aren't needed.  Then I use an adjustable temp probe to dial it in and fine tune it so the car can sit there and idle at the correct temperature.  Whatever value it ended up being that cut the fans on at the right time, I couldn't say for sure.  I do have it so both of my fans kick on at the same time.  They each have their own fuse and their own relay.

Edited by giantpune
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One thing you want to take into consideration, the thermostat doesn't just pop open at the rated temperature. The thermostat will start opening 5 to10 degrees before the rated temperature and then be fully open at around the rated temperature. They are not exact, remember, they work on wax melting and expanding.



“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein


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I watch Kenny Brown's cars and coffee on youtube on Saturday at 10:00 am eastern time. They sell a radiator for the racers, and told NASCAR also uses them, called a triple flow. When the water comes from engine on the right top there are dividers in the end tanks. So in the right flows to the left and drops down another third and back to the right. Then drops to the bottom third and back to left to water pump. Our stock and aftermarket just have the long open tank so not very efficient. I was shocked at the temps they want to run at when racing well over 212 deg. and run I think 24 lbs. pressure. He stated the hotter you can run the engine the more HP you get.
I would think you could take a stock radiator pull the tanks and make you some similar baffles. Might not be able to seal off perfect on the tank maybe add some rubber to the inside of the tank for the baffle to rest on. It does make sense to keep it in the radiator to cool and make it more efficient.

You can send in questions in real time for him to answer on the air. Also old sessions are kept so you can go back and review.

When a man is in the woods and talks and no women are there is he still wrong??:P


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