Gents,

I hope 2018 is treating you all well so far.

I'm running a single OEM fan and the TSE radiator. I've looked through a bunch of Miata tunes and I have seen the Fan Shutoff speed set anywhere from 40 mph all the way to 162 mph. I've read the fan blows (sucks) the equivalent of about 15 mph. What's the prevailing wisdom for a shutoff speed for an HPDE car that is driven to and from events?

Also, I have the fan set up to come on at 204 degrees and shut off at 197. Anything wrong with those numbers?

Thanks,

 

I have my fan shut off at anything past 90% throttle The other numbers seem good to me

 

I have mine a little cooler. On at 195 off at 190. Second fan on at 197 off at 190..only comes on in traffic. I turn them off at 40 mph.

 

The answer just depends on how well you ducted your radiator. When I had a conventional setup with A/C 30mph worked fine. With the v mount setup (no ac) and ducting 10mph works

 

That's awesome!

 

That's awesome!

 

Let me ask it a different way. Assume big TSE rad, 180 degree thermostat and decent ducting. No a/c.

Let's say I have the fan set up to turn on at 204 degrees, and to turn off at 70 mph, just for discussion purposes. If I'm traveling on the interstate on a really hot afternoon at 64 mph and I'm seeing 208 degrees, the fan is running. Is it doing anything positive for the cooling system? I'm also wondering if it's doing anything bad to the fan motor.

Thanks,

 

No the fan wouldn't be doing anything and the fan motor should be fine. If you measure the area of the mouth on the bumper you can calculate your airflow through the radiator at a given speed.


ENGINEERING.com | Air Flow Conversion Calculator

6"x24" opening at 70mph is 6160 CFM. My giant fan barely pushes half that.
The same opening at 25mph is 2200 CFM

You will have to verify the opening numbers because i just picked something random that sounds kinda close. But by those numbers you could turn your fan off at 40 and be just fine.

Hope this helps some.

 

It certainly does. Thanks!