Quote:
Originally Posted by qwerty
Let's assume that you have an 80* thermostat installed. (An 80* thermostat, when operating correctly, begins to actuate at 80* and fully actuates by 94*.) Due to existing conditions, the current coolant temp is 100*.
Now, let's assume you can instantaneously swap in a 60* thermostat, while all other variables remain unchanged. What is your new coolant temp going to be?
Is there any reasonable, rational or well-thought-out explanation for the temperature dropping from 100*?
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At a fixed load and fixed ambiant temperature, it'll take much longer (if ever) to reach 100c with a 60c thermostat instead of an 80c thermostat. The colder thermostat buys you time to get through the high load situation without ever getting close to a dangerous temperature. Thats the point people fail to understand. It takes a lot of energy to heat the water/coolant mix an extra 20c while the thermostat is OPEN and the radiator is doing its job.
I did a little kitchen experiment with the 71c thermostat I bought to install in my OM603. This was mostly to prove to myself that this Tstat opens earlier than stock. To my surprise the 71c Tstat didn't begin to open until about 77c and the 80c stock unit didn't begin to open until 88c. I verified that the thermometer is accurate with a different type of thermometer side by side. Its very unlikely that they're both inaccurate by exactly the same amount.
On the left is the old 80c Tstat which the previous owner said was replaced within the last year. On the right is the new 71c Vernet Tstat sold for BMW M20 and M50 engines.
80c, the Vernet Tstat is slightly open.
http://i.imgur.com/KHqxS.jpg
88c, the stock Tstat beginning to open.
http://i.imgur.com/ZiE4p.jpg
95c, Vernet is fully open, stock almost fully open. It didn't fully open until about 98c but that pic was blurry.
http://i.imgur.com/eikAB.jpg