No, you can’t move the coolant too fast through a radiator. That is wrong. Think about what yo are saying and what you want me to believe.
You are saying use less flow so the coolant stays on the radiator longer. So I’ll ask you. What happens when the coolant spends more time in the radiator???? The coolant in the block and heads spends an equally longer time picking up heat. So you gain nothing and lose the ability to keep the coolant temperature closer to the thermostat opening point.
It’s really that simple. If the coolant coming out of the engine is staying there long enough to leave at say...210ish, and the system is capable of a 20 degree temperature reduction then the best you can hope for is a 190 degree coolant temp. Doesn’t matter if you have 190 thermostat or a 160 degree thermostat.
If you speed up the coolant so it doesn’t stay in the engine as long and the coolant is now leaving the engine at say...195 then you can reasonable expect to keep the coolant right at the 190 degree thermostat opening.
So we can keep going. What if we can keep the coolant coming out of the block at 180 because it doesn’t stay in there so long? That would mean you could reasonably expect that with a 160 degree thermostat you would be right at thermostat opening. Maybe not on a 105 degree day, but certainly when ambient temperatures aren’t hotter than the hubs of hell.
With my cooling system, I run a 160 degree Stewart Components high flow thermostat and on 100 plus degree days it will run at 160. All day long. If I get stopped by a long train it might, maybe might climb to 170 or a skosh more. I’ve never seen it hit 180.
That’s one reason why you don’t slow the coolant down. Overdrive the pump as fast as you can find pulleys and to the limits of keeping the belts on and the fan blades on the fan.
