More Thermostat / Temperature data

[Bob Johnson]

Here are two sets of temperature data. The two tests were done going the same route. The ambient (air) temperature for both runs was 60-65 degrees F. The route started with city driving and at about the 5 minute (5:00 on the graph) I was on the highway going about 50-55 mph. There are 3 hills on the route. You can see them as the 3 peaks in the lines. The second hill is the steepest and shows the largest peak in the data. The in city data (before 5:00) is not comparable because in one run I had to stop at 3 traffic light and in the other run I made it through all 3 without stopping. So only look at the data after the 5:00 mark. Once the engine gets up to temperature the non-thermostat test is showing a lower temperature than the one with the wired open thermostat. The difference is about 10 degrees when the ground is fairly level. The difference increases to over 20 degrees when there is a hill to climb. Again the thermostat in the "green" test was "WIRED OPEN" so the difference has nothing to do with the thermostat opening and closing. I believe that the difference is due to the thermostat restricting the coolant flow.

I will post data from more tests as I complete them.


Bob

 

[pdora]

Bob --

I find your cooling system temperature posts very interesting, and would like to conduct similar tests myself.

What equipment do you use for the temp readings, and how do you get the data into graph form?

Thanks

 

[marc hildebrant]

Bob,

Thanks for the information. Question for you : Why does the wired open thermostat temp run cooler than the no thermostat at the beginning ?
If you are making a case for water restriction due to the thermostat (which seems reasonable), then why does it run cooler at the beginning ?

Could the answer be that the temp probe is up near the radiator and the hot water hasn't gotten there due to the restriction ?

Marc

 

[MikeK]

Well, this is quite interesting. Thank you!! Although this is a single test that has not been repeated, it clearly implies all those people who think slowing down the water through the radiator will make the engine run cooler are wrong! That argument never made sense from an engineering standpoint, anyway. Nobody in an old house ever argued that you could get more heat out of the boiler and into the living room by closing down the radiator valve.

Apparently Henry's puny impeller won't push quite enough water through a slight restriction. The flatty V8 boys have some aftermarket spiral impellers for their dual pumps that are said to cure overheating by reducing cavitation and moving more water. I wonder how a redesigned 'A' impeller would fare against a 'stat?

 

[Bob Johnson]

Marc,

As I said in the original post the 2 tests were not the same before the 5:00 mark due to traffic lights. There were several long stops with the non-thermostat test which allowed the temperature to rise. So the data before the highway should not be compared.

Bob

 

[Bob Johnson]

MikeK,

The test was done on my Model A which has a Model B engine and a Model B water pump. The B water pump is different than the A water pump.

Bob

 

[Bob Johnson]

How I did it.

Peter,

I took a broken motometer and converted it to a digital motometer. I used a meat thermometer. The sensor is at the end of the probe which I have located down into the hose coming from the top of the engine into the top of the radiator. Thus I get the readings of the coolant and not the air above the coolant. To record the readings I mounted my digital camera just behind the windshield on the passengers side of the car. I zoomed in on the motometer and took a video (movie) of the temperature readings. Now the hard part, I run the videos on my computer and read off the temperature every 1 second of the video. I put the numbers into a spreadsheet and from there I make the graph. Simple .

Bob

 

[pdora]

Wow.

The digital motometer is beautiful and elegant.

The rest of the project is a real labor of love.