Quote:
Originally Posted by dataway
Another point to keep in mind ... is we like to keep our vintage car engines less than the 195 degrees that the OEM considered appropriate.
This gets into some math, but the higher the thermostat setting is, the better a radiator works. Radiators get rid of heat using the difference in temp between the coolant and the air passing through. If it's 90 degrees outside, and you have a 190 degree thermostat then you have a 100 degree difference between coolant and air (delta T ).
If it's 90 degrees out and you have a 165 degree thermostat then there is a 75 degree delta T.
The size, flow, surface area etc. of an OEM radiator is based on some median combination of use cases and outside air temps WITH whatever temp thermostat they specify. Change the thermostat rating and it changes the entire dynamic of the OEM system.
A given size radiator's ability to remove heat is based on the rate of coolant flow, air flow AND the delta T between coolant and air.
Why does your engine run the proper temps in cooler weather? Because the delta T between air and coolant is larger. There are two ways to increase delta T .... lower ambient air temp ( talk to the man upstairs about making that happen) OR raise your coolant temps (by using a hotter thermostat). Of course this is a simplification, there are a lot of variables involved.
HWYSTR455 .... I'd love to attempt to create a complete mathematic simulation of a cooling system. A lot of the data is probably out there. Some kind of universal "plug in the numbers" simulation. I use Solidworks software, which does have a thermodynamics simulator ... but I'm not sure if it would allow all the variables we'd need. And it's doubtful it would provide any real world solutions for vintage cars ... but it would be interesting as heck.
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This is a really good point. Modern OEM vehicles also almost exclusively have dummy type gauges that soften the heat cycles as well. Oem's run cars around 200 degrees for stuff like the LS engines. They'll let that creep to 210-220 at idle before turning on the fan/s and bringing it down a bit. As soon as the ECU sees a specified MPH it'll turn off the fans entirely and the temps will come down to the rated temps.
As enthusiasts, most of us have gauges that don't dump down cycles, so when we see somewhat elevated temps, we freak out...often for no real reason.