|
I've been following this thread a bit with some interest, and in my mind, it's not solely related to the radiator because, as you keep pointing out, until the thermostat opens (to more than a trickle), the radiator isn't much of a factor anyway. But I've read an article once about how an engine gets cooled, and the radiator is only like 30% or so. I think more than that goes out the exhaust, a bunch is radiated through the oil & oil pan walls, while some is radiated directly through the block, heads, and intake manifold.
Now all this radiating that's going on will go faster if the temperature difference between the hot engine and the cold air surrounding it is higher. So to me, blocking the grille is like closing the doors & windows of your house on a cold & windy day. Even though your furnace would come on and keep your house warm (like the engine's thermostat), it would take longer. Blocking the grille allows more heat to stay in the engine compartment, slowing the rate of the engine radiating it's heat. (like closing the doors & windows in the house lets the furnace shut off sooner)
Of course, once the thermostat opens and the water flow through the radiator starts, it will be cooled less if the grille is blocked, too. So, to me, blocking the grille helps more of the heat from the fuel you're burning at the cold start stay in and around the engine than it would if a blast of cold air coming though the open grille was free to keep blowing it away.
So that would be my attempt to explain how a grille block helps the engine warm up sooner.
|