analytical2
Forum Newbie
Posts: 48
Reg: 11-18-10
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05-04-12 06:28 AM - Post#2222306
Guys I'm going to be running a 195 thermostat on my 64 project.
If I go with an electric fan could someone give me some guidance into what temperature it should cut on and then cut off?
Seems that most of the ones i see advertised on E-Bay are 180 on and 170 off which has confused me quite bit!
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fbi9c1
Frequent Contributor
Posts: 1660
Loc: Los Angeles
Reg: 08-07-07
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05-04-12 09:52 AM - Post#2222354
In response to analytical2
195 is the temp your stat begins to open, it is fully open about 15 degrees higher around 210 which is the lower end of your operating range. You need the primary electric to come on at about 220 with that setup. I personally don't like those sort of running temps and run a 160 stat with 185 and 189 fan turn ons. My car rarely runs less than 50 miles at a time and is a daily driver on Mobil 1 so I don't have to worry about it not getting warm enough to burn off crap that accumulates. Others will disagree.
Edited by fbi9c1 on 05-04-12 09:52 AM. Reason for edit: No reason given.
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analytical2
Forum Newbie
Posts: 48
Reg: 11-18-10
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05-04-12 01:00 PM - Post#2222419
In response to fbi9c1
Thanks Jim.
I've been having a heck of a time understanding all of this.
I see jegs has a harness and relay kit for a 195 thermostat that cuts the fan on at 205 and off at 185.
I may very well go with that one.
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 Vaughn
"11th Year" Gold Supporting Member
Posts: 13560
Loc: Colorado Springs, CO
Reg: 08-08-04
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05-04-12 02:59 PM - Post#2222453
In response to analytical2
The temperature of the radiator is not directly tied to the temperature that the thermostat opens - although a lot of people feel that it should be.
The radiator has thermal mass, which means that if you pour 195 degree water into it, it will take some time for the radiator to heat up to that 195 temperature - it has to mix with the water already in it that is at a lower temperature, which keeps the overall temperature down.
Usually, this means that you would normally want a electric fan relay set to come on at roughly 180 degrees - because prior to that temperature, there really is no need for the fans to come on. If you have a larger aluminum radiator, you can fudge that up to 195 degrees, if you have a smaller radiator you would want it to come on earlier, like at 160 degrees.
Generally, 180 degrees is fine for most applications.
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lakeroadster
Contributor
Posts: 368
Loc: High Plains of Colorado
Reg: 03-06-11
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05-05-12 05:01 AM - Post#2222614
In response to Vaughn
If you have a 195 thermostat, and a 180 degree fan switch, won't the fan run continuously once the engine starts to warm up, and then never turn off until you shut off the engine?
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Vaughn
"11th Year" Gold Supporting Member
Posts: 13560
Loc: Colorado Springs, CO
Reg: 08-08-04
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05-05-12 10:48 AM - Post#2222735
In response to lakeroadster
No, because you are forgetting the thermal mass. The 195 degree thermostat opens for a minute or two, dumping a small amount of 195 degree water into a larger amount of less than 180 degree water. Most of the water/antifreeze mix is in the radiator (about 4/5ths) and a smaller amount is in the block (1/5th).
For example - If you dump a small amount of hot water(say a cup) into a larger amount of cooler water (say about a gallon) - the mixture will result in a a slightly warmer cool amount of water. It is basic thermodynamics.
Because the radiator is a large surface area that is open to the airflow, it will tend to shed heat (generally) much faster than the engine can generate it. Only in situations like driving through the Arizona desert will the (properly sized) radiator start to approach a situation where it cannot shed heat faster than the engine generates it.
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