I'm confused. How can a car without a thermostat run hotter than with one? Allowing the water to stay in the radiator longer doesnt make sense, because while the water in the radiator is cooling down, the water in the motor is heating up. It's the flow into and out of the radiator that provides the cooling effect. Which means that more flow results in cooler temperatures. I am assuming that the radiator is sized correctly.
If you buy a 180 thermostat, it opens at 180 degrees. If you buy a 120 thermostat, it runs at 120 degrees. That means that the lower the thermostat, the lower your temperature runs. That implies that no thermostat will provide the lowest operating temperature. Ever had a thermostat stick open? No heat at all, and the temp gauge stays on the cool side. Thats the same as having no thermostat at all.
