Quote:
Originally Posted by zippy
It's true. DeltaT time constant. Many years ago I tested that with my TA. And many others have too. Easy test. Take out thermostat completely. Max flow ytour cooling sys will get that way. Yup, take forever to warm up. And in town, slow stop and go driving, sure prob run cooler, as flow is cooler with lower RPM and engine power/throttle level
Now go on highway, go for a long hard rip. and keep in her for a while
Logic would suggest that then we have
More airflow due to speed
More coolant flow due to much higher RPM
But you will start having climbing temps. They will start creeping up and up and up.
You slow down and the temps go up even more before they start to come down
Why? The coolant was going so fast through the radiator that it had no time to remove enough of it's retained heat. Engine to coolant DeltaT is greater than the coolant to air DeltaT
Meaning, needs more time in rad to remove the heat than it does in block to pick up heat.
Scenario above, Put T stat back in and engine is stable at same high rpm load. Verifying flow speed matters
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Except that when you do your highway speed rip at higher rpm you not only increase coolant and air flow, but you increase heat generated by engine. So is your increase in temps due to coolant flow, or does the rate of heat generation now exceed rate of heat removal?
Your thermostat shuts to increase coolant temp, and opens to decrease it. Less flow equals increase temp, more flow equals decrease temp. From the factory, hd cooling/ac got smaller diameter pulleys for more flow. Engineers designing these systems knew more flow is better. More coolant flow, more air flow, more surface area, reduced ambient - all are factors to help cooling.
Good stuff, tho.
