170 Degree Thermostat

 Our 170 degree thermostat is based on a popular Stant thermostat. We modify it to have the same form factor as the OE LT5 thermostat.

The OE thermostat was made by Stant. It is a 180 degree unit. This is listed in the car owner's manual and the service manual. The thermostat controls the temperature of the coolant going into the engine at the water pump. The temperature sensors are located at the left top front of the engine. There is typically a 15 degree temperature rise as the coolant passes through the engine. With the 180 degree thermostat the coolant temperature at the sensors is about 195 degrees when the AC is off and the car is moving over 30 mph. The cooling fan control strategy in the GM engine calibration chip turns the fans on at about 230 degrees. When the car is idling with the AC off the engine operates at about 230 degrees.

With the 170 degree thermostat and the car moving at 30 mph the engine will operate at about 185 degrees. With the GM engine calibration chip the fans still control the temperature at idle at 230 degrees. The engine calibration chip can be programmed to operate the fans to control the engine temperature at 190 degrees at idle.

The analog temperature gauge in the cluster positions at about 50% of the sweep at 200 degrees. It is at about 75% of the sweep at 230 degrees.

The above information assumes that the radiator is not obstructed with debris. The radiator is at the bottom of a stack of three heat exchangers. View the radiator's face from the right side of the car where the oil cooler lines enter the shroud. It is also assumed that the ambient temperature is less than 90 degrees.

The cost for the thermostat is $110.

A tapered thermostat gasket that makes the installation easier costs $14.