"If you remove the thermostat from your car will the increase in coolant flow cause your motor to overheat?"

or put another way

"Can the coolant flow too fast through your radiator and decrease efficiency?"

The answer is Yes AND No.

First and foremost, coolant flow can never be too fast. The faster the coolant flow the more even the temps will be.

Can removing your thermostat cause a motor to overheat? The answer is YES but not for the reason we were discussing.

Removing the thermostat can cause overheating because it decreases the pressure IN THE ENGINE ITSELF. The thermostat is a flow restriction and the water pump, pumping against this restriction, causes an increase in pressure in the engine block which raises the boiling point of the coolant. The average Radiator can handle somewhere around 15 or so pounds of pressure, where as the water pump can introduce up to 40 PSI ADDITIONAL pressure in the block itself. Removing this restriction decreases this pressue, which drops the boiling point and increases your odds of getting hot spots or steam pockets.

By the way, when I asked these questions they were met with much laughter, as in "Man have I heard this before!"

Another popular misconception that he also displaced was running temp in relation to horsepower. All things being equal a hotter engine will produce more power with less fuel than a cold one. The primary reason that people think cold engines produce more power is because of the decrease in intake air temp. If you can maintain a cool intake charge AND keep you temp at a steady 200, as apposed to 160 to 180, you will make more power and use less fuel.

A personal comment on this, is to me this seems obvious as horsepower is a funciton of heat produced by combustion, and that a cool block will obsord more heat than a hot one. I know that in NASCAR, and other circle track events, the cars are running at a steady 250 to 280 degrees for long periods of time. This is not because that is as cool as they can get it. It is because that is as hot as they can manager with the coolants they have currently. It has been rumored that in Formula 1 and Indy cars they are running with a steady state temps of 350+ with exotic coolants and very high pressures and flow rates.

Thanks for the follow-up to an interesting question

SteveW