Another Fan "?"

MrMopar64 · February 05, 2006, 02:53:58 PM

I bought a nice electronic fan controller....... Now I need to know what the
Best setting would be.... The controller has a range from 150 to 240
The car has a 160 thermostat.... Right now I have it set to come on at about 185 then shuts it off at about 165 I have no way to set the off temp
My understanding is the higher I set the on temp the higher the off temp will be
So my "?" is.......... Is that range ok or should I move it.... up or down?

Thanks again

MM64

donsrods · February 05, 2006, 04:11:29 PM

Good question, and I don't know if this is correct, but I have my Jeep set at 185. I figure it runs at 180 going down the road, and at lights it comes up to maybe 210, so if I set it slightly higher than where it runs when moving, it won't be on all the time, and yet it comes on soon enough to keep the temp in a reasonable range.

I just rented a Chevy SUV on a trip I took to Minnesota, and it ran at 220, and that was the normal temp for that car. I guess newer cars are doing that for emissions reasons, but high temps scare me to death. I'm old fashioned.

I would say, figure out where your car likes to run when you are moving, and set the temp 5 or 10 degrees above that. The shut off will happen automatically when the temp drops again so don't worry about that.

That is just my laymans opinion, but I'll bet some of the sharp people on here will have a more accurate answer.

enjenjo · February 05, 2006, 05:33:35 PM

Yes you are old fashioned.

All things being equal, the hotter you can run the engine without having the heat run away, the more hp you produce, and the more efficient it becomes, giving better mileage. The limitation is the ability of bearings, rings, oil, and so forth to withstand the heat inside the engine. This temperature used to be about 240 to 250 degrees, but has increased to about 260 to 270 degrees with modern technology.

That's the reason behind pressurized cooling systems, and thermostats. to hold the temperature at the MINIMUM level for the engine to run efficiently. By raising the boiling point of the water, and raising the thermostat setting it gives better performance.

There is an old wives tale that a thermostat aids cooling by slowing the coolant down. This is untrue. The thermostat aids cooling because it causes turbulence in the coolant, causing more of it to reach the inside surface of the radiator where it can shed heat. By "stirring" the coolant, it makes the cooling system more effective. It also aids cooling because it holds a positive pressure on the block, raising the boiling point of the coolant in the block, reducing the "spot" boiling of the coolant. That is also why a restrictor helps too.

OE thermostats have been in the 195+ range for over 20 years now, that is about the maximum safely with a carburetor. So of the EFI cars are 205 now. EFI engines can do it because the computer will adjust the fuel mixture to keep it from getting lean at that temperature.

Now as to the fan control, I agree with Don, set it at about 190, so it doesn't fight the thermostat. Most OE controls are set at 205 to 210 now days.

donsrods · February 05, 2006, 11:02:59 PM

Well now. Don't I feel stupid!!

MrMopar64 · February 05, 2006, 11:24:39 PM

Quote from: "donsrods"Well now. Don't I feel stupid!!

Hey Don
Did you miss this line........... "I agree with Don"

And thats from the "MAN" himself....

If nobody else has an answer Frank will

Thanks guys...... I'll bump it up alittle and see what happens

MM64

donsrods · February 06, 2006, 12:13:29 AM

No, I saw it, and the smiley faces. I just don;t know how to put those faces on my posts yet, so I couldn't convey I was kidding too.

Guess I should have put "just joking" on there, cause I was.

Thanks, Don

enjenjo · February 06, 2006, 10:45:10 AM

I got a lengthy Email this morning from a man who generally knows his stuff, and lurks here a lot. He disagrees with me that the restriction helps cooling by slowing the flow of coolant, and gives some real world testing to back it up. His example shows that, A, I'm wrong, or B, there is something going on that neither of us understands, and knowing him, I vote for A.

His testing shows that a restriction on either hose has the same effect, aiding cooling. So other than slowing down the flow, restricting the coolant would have no effect on turbulence in the radiator, if it was in the hose returning the coolant to the block.

So we disagree on cause, but agree on effect.

donsrods · February 06, 2006, 11:54:46 AM

What's the old saying " opinions are like belly buttons (or some other part of our anatomy) we all have one, and they are all different."

I tried applying another smiley face, still no go.

Don

donsrods · February 06, 2006, 11:55:53 AM

Hey, it worked!!!!!!!

:?

:x

:oops: :cry:

Cool.

Bruce Dorsi · February 06, 2006, 11:44:32 PM

Quote from: "enjenjo"

There is an old wives tale that a thermostat aids cooling by slowing the coolant down. This is untrue. The thermostat aids cooling because it causes turbulence in the coolant, causing more of it to reach the inside surface of the radiator where it can shed heat. By "stirring" the coolant, it makes the cooling system more effective.

I agree that turbulence is beneficial to cooling, but is the thermostat the PRIMARY source of turbulence?

I believe (perhaps, wrongly!) that the turbulence created at the thermostat converts back to laminar flow as it passes through the upper hose. ....That laminar flow is then disrupted as the coolant is forced to split-up to enter the tubes inside the radiator tank.

Those flexible radiator hoses are often held in disdain as a "restriction to flow," yet they may actually promote turbulence.

Small points to question, I know, but that is how my mind works, or maybe, malfunctions.

Mercedes used an aluminum radiator on many of their diesel models. ....Instead of oval or flat tubes, they had round tubes. ....Inside the round tubes were spiral strips of aluminum which "swirled" the coolant against the walls of the tubes to promote heat transfer.

Bruce Dorsi · February 06, 2006, 11:54:03 PM

Quote from: "enjenjo"I got a lengthy Email this morning from a man who generally knows his stuff, and lurks here a lot. He disagrees with me that the restriction helps cooling by slowing the flow of coolant, and gives some real world testing to back it up.

His testing shows that a restriction on either hose has the same effect, aiding cooling. So other than slowing down the flow, restricting the coolant would have no effect on turbulence in the radiator, if it was in the hose returning the coolant to the block.

So we disagree on cause, but agree on effect.

If that e-mail was from one of two guys I have in mind, I respect their knowledge!

However, I wonder why GM would overdrive their water pumps on many engines, if slowing the coolant flow is beneficial?

?

donsrods · February 07, 2006, 08:10:19 AM

Maybe it would be beneficial to many of us on here to solicit a post from some manufacturer of cooling system parts, as I am sure their engineers know what works and what doesn't.

I'll make a few calls today, and try to get one of them to contribute their knowledge. This subject seems to be one of concern to all of us, given the fact that we shove huge engines into compartments made for smaller engines, and bump heat generating horsepower into those same engines.

Will let you all know what I find out.

Don

PeterR · February 07, 2006, 08:42:11 AM

Quote from: "enjenjo"His example shows that, A, I'm wrong, or B, there is something going on that neither of us understands, and knowing him, I vote for A..

There could easlily be an option C, which is a combination of A and B. Something along the lines of, -there is a lot in this that none of us understand, and an obscure explanation showing that both are half right, or half wrong depending on your point of view.

I have a gut feeling, (which is defined as a theory for which there has not been adequate testing) which suggests to me: -

That for each engine and radiator combination there is an optimum coolant flow which produces the greatest rate of heat energy transfer from iron to air.

That for most large auto engines with sensible radiators the OEM pump is not large enough to achieve the optimum flow rate. This has led to the all encompassing belief more flow is always better.

Where an aftermarket hi flo pump is fitted, and on small engines where the OEM pump is proportionately larger, it is possible to go over the top of the curve particularly if the radiator is undersized. So in some unusual instances a lower rate improves total heat transfer.

That the effect of turbulence caused by a thermostat is over estimated because while travelling along the hose and upper tank the fluid reverts to the laminar D profile.

That there is a lot more in the thermodynamics of an automobile cooling system than first appears, and surprisingly little scientific literature on it.

And of course most importantly " opinions are like belly buttons (or some other part of our anatomy) we all have one, and they are all different."

.

donsrods · February 07, 2006, 08:56:29 AM

PeterR: You are correct about the lack of literature or information.

I phoned Walker Radiators, and spoke to a nice man there who understands what we are looking for, and took the site info, and promises to have someone call me, and possibly post some information on this subject.

Many of us are using their product, so it would be nice to get some feedback from them on what we should be looking for in a cooling system.

Not that all the stuff that has been posted already isn't good, but it can't hurt to have input from someone who makes their living in this field.

Hope none of you mind me doing this. :?:

enjenjo · February 07, 2006, 09:58:44 AM

Well, I think we can all agree that fluids can do some strange things.

I had a Ford truck one time that had a 390 engine in it, when the engine went bad, I replaced it with a fresh 350 Chevy. It started overheating. I went through all the usual things, and could find no problem.

When the engine was changed, the radiator outlets had been switched side to side on both tanks, but nothing else was done to it. So I took it to a local shop to have it rodded. When he pulled the tanks, I looked in the top tank, and there was a diverter where the old hose entered the tank. There was very little crud in the tubes, so I had him move the diverter to the new hose location, and put it back together. It cooled fine after that.

Some of the truck radiators I have worked on had dimples pressed into the tubes, they may be there to perform the same function as the internal fins Bruce mentioned.