Quote:
Originally Posted by Christ
That's not true at all. The thermostat doesn't just stay open, this is the reason that grille blocks afford a shorter warm up time. The thermostat opens when the water touching it reaches a specific temperature. As the flow rushes past it, it cools down, lower than the temp at which the t-stat would be open, so it closes again. This heats the water up again inside the block. This happens several times before the engine has actually warmed up. A smaller radiator (or a grille block) prevents the water from cooling as much between cycles, so there are less cycles of heating and cooling until complete warm up.
I don't run with no thermostat. It was a goal I had, to be able to run without one and still have normal warm up times and no overheats. T-stats represent a fairly large restriction to flow, even when open fully, which loads the water pump. It's a negligible amount of power, but it's not like it'd be hard to do, and the smaller radiator has obvious aero benefits as well.
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The thermostat has a specific range between it's opening and closing. (Probably about 20 degrees) After it opens to a cold radiator it will then close when the temp drops to its closing point keeping the motor temp within the thermostat's range. As long as the motor is in this range it is "warm". A smaller radiator will reduce the number of thermostat cycles but at no time during these cycles does the motor temp get less than the closing temp of the thermostat.
The only way a grille block would speed up warmup is through the reduction of cooling air flow through the engine compartment.
The restriction to water flow provided by the thermostat is necessary for efficient cooling. It slows the flow of the water to give the heat time to be extracted by the radiator. In a race car with no thermostat they put a restrictor in to accomplish this. Keeping up your cooling efficiency is even more important if you are reducing the efficiency of your radiator with a grille block.