Why buy a cooler thermostat?

Too little or too much of anything most likely hurts I think? Too much heat would be a common enemy for an engine. But you do ask a good question, I'm not exactly sure

People claim that running a colder thermostat can do damage because of accelerated cylinder wear. A guy once made this argument with me and I asked him why the cylinder wear, he says that because of the lower temperatures the cyliders are smaller (he is correct about lower temperatures and shrinking casting) but I am not sure if this is enough to cause cylinder wear. A lot of people won't do it because in the winter you don't get enough heat. Another reason people won't do this is because your EEC is calibrated to run on the stock (180deg I think) thermostat. By lowering the thermostat to say 160, your car may never run to it full potential. Now whe you buy a supercharger, like mine, they run a cooler thermostat as a saftey measure for detonation, but the computer is also reprogrammed with the chip to adapt. And they claim that the test they have done show any proof of accelerated cylinder wear. This is my .02

Good question. Anyone have a URL to a real explanation?

You are correct in saying that higher temperatures mean more energy. Hoever, it would be best if you could keep the engine cold at all times. If you could do this, that means that all the energy in the fuel went in to moving the piston and not into the engine itself. When I say keep the engine cool, I mean no coolant, that the outside of the engine is the same temperature as the outside of the piston wall, i.e. no heat is transfered from inside the piston chamber to the engine. As it is, most modern car engines are somewhere in the 20-30% efficiency range. Meaning that 70-80% of the energy from the fuel went out your tailpipe, into the engine block, into the coolant, into friction, etc.

Remember, this is all in theory. The above is based on thermodynamics not car mechanics.

I am not sure about the cooler thermostat. I would assume the more heat that can be drawn away from the engine(I am sure there is a limit) the better. Less wear on the egine(maybe), or the more the timing can be advanced due to a cooler engine.

Did a quick search on Google for "cooler thermostat cyliner wear" and came up with a bunch of links. Here is one.

http://performanceunlimited.com/cobravalley_drivetrain/thermostat.html

Seems to go with what I always heard that you really don't want to go below 180. I believe the stock thermostat in the 4.6 is around 195.

Stock is 195. I installed a 180 degree thermostat in my '04 since I am running a Diablosport tune and it likes to kick the fan on real early and it stays on for a long time. After going with the 180, the fan kicks on when it used to before I installed the Predator tune.

so the bottom line is:

a.) is it better for a stock Mustang GT to have a thermostat?

b.) leave it stock

?

I remember back in the day when all the Hypertech chips came with your choice of 180*(Street) or 160* (Race) thermostats. I never really understood why unless there was a correlation between the amount of timing with the chip and the thermostat.