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Old 11-19-2012, 08:42 PM   #41 (permalink)
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Here is how you should consider radiator size or capacity. Imagine if you could precisely control the temperature of the coolant coming out of the radiator. This would allow you to keep the thermostat wide open, preventing the water pump from working against the restriction of a closed thermostat. It would also keep the cooled coolant at the best temperature for another circuit through the hot engine. Just enough heat removal to allow sufficient cooling to prevent overheating, regardless of the load or whether that load is sustained or temporary.

Radiators, being designed for the absolute worst case scenario, have way too much capacity for any typical hypermiler. In fact, in severly cold extremes, many hypermilers could probably keep the engine cool with only the heater core!

Most cooling systems have a bypass circuit, so the engine can circulate coolant even while it is warming up, just not through the radiator. I do like the idea of a radiator with sections that can be eliminated to keep outlet temperatures higher.

Think of it, when radiator coolant exit temperatures in wintertime when the coolant flow is restricted by the partially open thermostat. The coolant exiting the radiator in those instances can be as much as 100+ degrees colder than coolant on a hot summer day.

We used to do a quick checlk on radiators by holding on to the top hose (hot) and the bottom hose (cooler). The difference in temperature would become less and less as the radiator slowly became clogged over time. By the time the car started overheating the temperatures were almost the same since the radiator was not "radiating" any heat.

What I found after replacing the radiator with a new one was some customers who actually keep records of their mileage would inform me of a loss of MPG, particularly in the winter, when they had the new radiator which removed more heat and returned much colder coolant to the engine.

regards
Mech

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