i am thinking about getting a colder thermostat for my ls1 what would be better for performance stock,180, or 160 degree? i was going to get a 160 but would like more info thanks.

 

A cooler t'stat won't do much good unless the PCM is tuned to turn the fans on at a lower temp. The engine will run cooler at highway speeds because air is rammed into the radiator. However; in traffic the temp will continue to rise until the fans come on. A cooler running engine will make a little more power, nothing to write home about, but if you are in sanctioned drag racing every 0.001 second helps. The down side is that the oil temp does not get to a high enough temp to boil all the bad stuff out of the crankcase.

 

Pete is right on the money with this. Just to throw in some of my knowledge. If the thermostat needs to be replaced, install one with the same temperature rating as the original. Using a cooler thermostat (160 or 180) can increase fuel and oil consumption, ring wear and emissions. On newer vehicles with computerized engine controls, the wrong thermostat can prevent the computer system from going into closed loop resulting in major performance and emission problems if the engine fails to reach its normal operating temperature.

(Taken from one of my previous posts about the cooling system)