Taking the thermostat out can actually cause overheating. Without the thermostat, there is no restriction there, and the coolant can run thru the engine too fast to be able to remove the heat from the engine. Nascar racers run no thermostat, but they DO run a restrictor, which is basically a plate with a hole where the thermostat would go. The coolant has to be in contact with the engine block long enough for it to remove the heat.