Re: Engine Temp?

Posted by Owen_Dyneto On 2009/8/27 18:30:30

Cost-cutting was perhaps an important factor, but another was engine efficiency, with the side benefit of better hot water heaters to replace exhaust-gas powered heaters. Engines run with very significantly better efficiency at higher temperatures and the common antifreeze up to the mid 30s was methyl alcohol which begins to boil just above 160 degrees, so the non-pressurized systems of that era used thermostats of that temperature or less. My 34 Eight has a Pines Winterfront and the standard 160 shutter stat, and the car pretty much runs at 160 regardless of conditions.

As ethylene glycol antifreeze began to gain acceptance, it allowed manufacturers to raise temperatures to get better engine efficiency and also enhance the performance of hot water heaters. Some of these systems were still unpressurized. But just raising the thermostat setting with no other changes brought the operating temperature closer to the boiling point, leaving little margin for overheating.

Pressurizing the system allows you to obtain a reasonable elevated margin between operating temperature and the boiling point. The pressurization does not raise the temperature of the coolant, only it's ultimate boiling point while under pressure.

Take off your pressure cap on a cold engine and start it; and with the cap removed and by watching the water flow in the top tank, you can see when the stat opens by the beginning of turbulent flow, and this starts at the thermostat rating, neither higher nor lower because of pressurization or lack thereof.