| Author |
Message |
david anderson (Davidanderson)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 27, 2005 - 4:29 pm: | |
I've been chasing the summer high temp gremlins in my Eagle 10/ 6v92 since returning from Busin USA. I failed in my attempts at finding a larger radiator at a reasonable price similar to the one Joe Laird installed in his Eagle. Jefferson Truck has one for $2150 which is too expensive for me to buy right now.
In an attempt to make one last stab at a no cost/low cost fix, I took out the radiator and repositioned the fan shroud farther back from the radiator. This put the fan blades farther inside the shroud cone. I had to redo the baffling to get a good tight fit against the radiator. I also plugged every inch of holes, gaps, cracks, etc, in the shroud to totally stop any chance of air leakage around the fan suction area. This was no easy task, but didn't cost much at all other than my time.
Two other things I did, replaced my 170 t-stats to 180's and changed my antifreeze mix to 60% distilled water, 40% precharged antifreeze. DD allows 100% distilled water with the proper SCA, but I don't want to go that far. I would be boiling in the mountain passes at about 190-195 degrees. If I go in the mountains this winter, more freeze protection can be added. I will watch the mixture closely.
The results: I took the bus out Aug 26 and ran it as hard as I could on some rolling hills south of town. Ambient temp was 103. The temp gauge never went above 185. That's good and improved for me. Previously, in those condiditions it would creep to 195-200. It never dropped below 180. I like that. Previously, it would drop to 168-170 with the old t-stats. I never really liked those swings from 170 to 200 I had in the past.
Another result and this really impressed me. My temperature delta from the radiator top tank to bottom tank was 24 to 28 degrees. Before the tinkering I could only get a delta of 12 degrees between tanks.
I attribute this to the shroud mods and though not sure, the 60/40 antifreeze mixture. You guys post regularly that water is a better coolant than antifreeze and some of my improvement may verify that.
Hopefully, I've gained enough cooling to keep that 200 degree light out. Though the conditions I drove through in Nevada and Utah from Busin USA were more harsh, gaining 10 degrees of reduced average radiator core temperature is substantial and may make another trip much easier than the last.
I will still keep my eyes out for a larger radiator if one comes available. That would definitely solve the problem for good.
David Anderson |
David Hartley (Drdave)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 27, 2005 - 6:26 pm: | |
Attention to detail is the best engineering of all.
Sounds like you may have hit upon a great idea for those of us that are too lazy to pay attention to all those little gaps, cracks and holes in the fan shrouds.
People don't always understand that for a radiator to cool properly you have to allow the water to stay in the air flow for a while before dumping it back into the engine to absorb more heat.
Thermostats do that, They restrict the flow according to temperature range just enough to allow the water to cool down in the radiator and mantain proper engine operating temperature.
The funny part is that without the thermostat the engine will usually overheat.
Sorry, What you said just reminded me of that stuff... |
Tom Caffrey (Pvcces)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 05, 2005 - 10:30 pm: | |
"The funny part is that without the thermostat the engine will usually overheat."
David, I am having some trouble with this statement. Even if the water goes through the radiator very fast, it seems to me that the total heat rejection could only increase, not fall, if the thermostat is removed.
I figure that David Anderson's improvement comes from other causes.
For what it's worth.
Tom Caffrey PD4106-2576
Suncatcher |
Richard Bowyer (Drivingmisslazy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 06, 2005 - 1:18 pm: | |
My experience with Model A Fords is that a large washer placed in the water outlet from the engine to the radiator hose slowed the water down and the engine ran cooler. Also, on the early flat head Ford V8's you had to leave the thermostats in to provide proper cooling. The water is travelling so fast through the radiator that it does not have time to cool properly. At least that's my opinion.
Richard |
David Hartley (Drdave)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 08, 2005 - 8:17 pm: | |
Tom,
I had this huge explanation all typed in the other day and my internet link crashed just as I hit the post button. Everything went into slow motion mode.
Oh. Well. not that it mattered. Here is the condensed version.
You have to slow the water down for the air to take the heat away through convection. The water uses conduction to absorb the heat and the radiator also uses conduction to carry the heat to the air flow. This requires a certain amount of time to elapse for the convection to occur.
The example would be your A/C unit on a hot day. Measure the air temperature with the fan on high and then with it on low. The slower airflow will let the air be cooler because it's in contact with the coils longer.
It thermodynamics in operation. Water flowing too fast can't dump its heat load as well because it needs to dwell in the cooler air flow longer for the actions of conduction/convection to take place. |
Tom Caffrey (Pvcces)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 09, 2005 - 10:40 pm: | |
Thanks for the post, David. The air conditioning behavior is a good example of what we're discussing, all right, but it seems to me that if the bottom of the tubes cool off, then they're not going to dump much heat.
In the case we were talking about, the hot water leaves the engine and passes through the thermostat into the radiator and returns to the engine.
If we slow the water down passing through the radiator, then the bottom of the radiator will be given a chance to cool off.
What I would think would work better is if all of the radiator stayed nearly as hot as the engine temperature.
With all of the radiator hot and with the amount of air passing through it unchanged, the air will absorb more heat. Since that's what cools the engine, I don't see how dopping the radiator temperature at the bottom will help.
Besides, that's exactly what happens when the radiator tubes become plugged. An infrared thermometer is used to find this condition.
I just wondered what you were talking about.
Tom Caffrey PD4106-2576 |
David Hartley (Drdave)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, September 10, 2005 - 7:57 pm: | |
The top should be hotter than the bottom. If the bottom tank is cooler than the top of a working and flowing radiator that means that it is working as designed.
The difference of temperatures means that as the water flows down through the tubes the air is absorbing the heat.
A radiator that is the same temperature at the top and bottom is not efficient in fact its not working or you don't have enough air flow to extract the heat from the tubes. The engine temperature will continue to rise and steam or engine damage will result providing the hoses don't explode first. The other catch of this is that if the water flow is too fast it will cause the same effect, the water will heat and heat and not have time to radiate that heat to the air flowing through the radiator.
Ok, Now were are in a loop here going over the same effects with all the same outcome. Paradox.. |
Marc Bourget
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, September 11, 2005 - 11:33 am: | |
Not exactly,
While extra rows of tube will increase overall cooling capacity, unless it's intellegently designed and intelligently installed a larger radiator MAY result in delivering the same or possibly less "net" cooling to the engine.
For effective heat transfer the speed of the coolant through the individual tubes has to be sufficient to cause turbulance sufficient to "exchange" the hot coolant with the "cooler" coolant closest to the tube walls. Coolant, and air for that matter, of different temperatures don't like to mix.
The simple "fix" of adding a larger radiator isn't always the correct answer. The larger radiator has to be coordinated with water pump volumne and the engine, coolant filter and heat exchanger's rate of coolant flow in order to work effectively. Same thing, but in a slightly different way for the air flowing through the core of the radiator, but that's a different story.
BTW, it isn't "pure" speed. It's the correct speed dictated by the Reynold's Number (a scientific formula)
Overal, it's kinda like the three bears, too fast, too slow and "just right"
Best to get it "just right"
Onward and Upward
Marc Bourget |
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