What is the optimum operating temperature for engine?

Discussion in 'Classic Mustang Specific Tech' started by 65 fastback, Jul 15, 2009.


  1. 65 fastback

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    At what temperature should I set my new electric fan to come on? I have a 180* T-stat, so I was thinking I should set the fan to come on at 190 or 200.

    Tim
     
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  2. 2+2GT

    2+2GT Well-Known Member

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    I knew one of the engineers who worked on engines for Ford, and he told me they were intended to run best with a 190° thermostat. I like to use the genuine Ford unit, very high quality and has bleed air valve which eliminates all those problems bleed ing the air out of the system.
     
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  3. D.Hearne

    D.Hearne Banned

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    Run whatever T-stat keeps it in the 180-210 range. The exact T-stat rating will not always do the job in keeping the temps where you want em. Start with a 180*. If it runs hotter, try a 160*. If too cold then try a hotter one.
     
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  4. rbohm

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    i would set the fan to come on at about 205-210 degrees and off at 185. keep the tstat you have now as it will work just fine with an electric fan.
     
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  5. wicked93gs

    wicked93gs New Member

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    for me I like my fan on at 195 and off at 190...my preference...190-195 is the ideal temperature for gas mileage...anything over 170 is ok(as long as its not too hot of course)
     
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  6. dinger2

    dinger2 New Member

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    Where are you finding these ford stats with the bleed hole. I can't locate anything like it even when searching for ford OE stats? Any links?

    Thanks
     
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  7. D.Hearne

    D.Hearne Banned

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    You can make your own, just drill a 1/8" hole in the upper flange (as it sits in the housing)
     
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  8. brianj5600

    brianj5600 Active Member

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    My thermostat housing has about a 1/2" bypass hose on it. What will adding a hole in the t-stat do? I thought that was a chevy mod.
     
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  9. D.Hearne

    D.Hearne Banned

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    It lets any trapped air out into the upper hose
     
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  10. Decurion

    Decurion Member

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    No need for a bleed hole when you use a vacuum venturi cooling system refiller. Matco #mcr101. It pulls the cooling system down to about 26" vac, then flip a valve and use the vacuum to pull the coolant in. Thats it, no more bleeding the system. Its not really a necessity on older cars, but starting in the 90s cooling systems started getting pretty complex which makes them impossible to bleed the old fashioned way. I vote for a 180* stat, fan on at 195, off at 190.
     
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  11. rbohm

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    my problem with such a narrow range is that the fan is constantly turning on and off, and that is hard on the fan and the relay(you ARE using one right?), and it doesnt give the fan motor time to cool off a bit before it is running again. a wider range like i suggested gives the fan motor time to cool a bit before turning back on, and it takes the constant on and off loads away.
     
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  12. D.Hearne

    D.Hearne Banned

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    If you can fit a big enough radiator, you can damn near eliminate the fan's function. But that's a bit hard to do in most cars.
     
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  13. jcp123

    jcp123 New Member

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    180-190 is probably an optimum mix of economy, performance, and longevity. The hotter the better the fuel economy, but running colder doesn't necessarily better your performance.
     
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  14. blown65

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    Besides EFI, why would running an engine hotter equal more hp and better performance? From 130 or so degrees to an engine temp of 160 on my car is a loss of about a tenth in the 1/4 mile. Hell, there are guys that run ice to cool thier cars, have flush kits to cool them down. They must be crazy!
     
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  15. jcp123

    jcp123 New Member

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    Nope, hotter just enhances fuel economy, for the same reason it hurts performance. Thinner air. Didn't mean to imply otherwise. Cooler, depending on the oil, though, can mean it's thicker and hold back performance (somewhat - the difference may be academic). The secret is to keep the air charge cool, even if the engine's running warm, if you're chasing power, where a warmer air charge is in your interests for fuel economy.
     
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  16. blown65

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    no problem, not picking on you directly. I see this posted now and then on here by others and it drives me nuts. LOL

    On the street I have a fan switch that lets mine heat up, but at the strip I always go faster the cooler I get the motor. Cold engine Hot oil. :)
     
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  17. jcp123

    jcp123 New Member

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    You're good :) cold engine, cold air, hot oil. A good combo for the strip!
     
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