Quote:
Originally Posted by campisi
I'm still not getting it .... if the coolant coming out of the radiator is so cold then the engine will cool off AND the tstat will shut off and then NO coolant goes to the radiator thereby warming up the engine again. Seems like a grill block wouldn't make a difference in this control system unless the problem is one of the engine getting up to temp and then the very cold coolant bringing it back under temp over and over again. That would make sense in that a grill block might stop that from happening.
Not questioning the aerodynamic benefits of the grill block just the statement of fact that a grill block helps keep the engine warmed up.
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The thermostat will not "shut off". It will restrict the outlet coolant flow which makes the coolant exiting the radiator even colder which exacerbates the issue with engine heat being lost to the now much colder coolant.
Try to understand this if you can, the cooling system is designed for the worst case scenario which is 120 degrees ambient, with maximum load, climbing a significant grade. Under this circumstance the coolant exiting the radiator will be about 30-40 degrees lower than the coolant exiting the engine and the thermostat will be wide open.
Anything less than that and the coolant exiting the radiator will be colder than 140-160 degrees. As I said before, and I have tested it which you can do also if you have difficulty believing simple physics, the coolant exiting the radiator is where huge temperature differences occur. In winter with very cold ambient temps and hypermiling that temp can drop to close to ambient, even below freezing under extreme circumstances.
Every degree you can add to that coolant temp by reducing the effectiveness of the radiator means more heat is available for combustion pressure versus heat absorbed into the cylinder walls.
Several new car manufacturers are doing this with automatic adjustable grille blocks. Thye would not waste the money if it was not effective.
regards
Mech