I have read on here that a 180 degree thermostat is a good mod to the 4.7, for performance reasons, however I do not understand why.What does raising/lowering the temp do to the motor? does this effect the fuel economy ??

 

an engine that runs cooler will run more efficient.

 

It causes the PCM to treat the truck like it's still warming up all the time. Raises the idle slightley - good band aide if you truck stalls at idle.
It makes the A/F ratio slightly richer, a slight gain in performance but you'd need a dyno to tell.
It keeps the engine a bit cooler, which in theory anyway, prolongs the engine's life.
Fuel economy will drop, because of the rich state, meaning the ratio of fuel to air is slightly higher. Again the amount is small so the mpg loss is very small, possibly not even noticeable.

My theory on them is this: If you stall because of low idle, get one, cheap fix. If you are running lean due to some mods, such as CAI, Headers and a tuner which advances the timing all lean out your mixture. A lower temp t-stat will bring you back closer to spec.
Nobody has ever really proven or disproven the engine longevity theory, although it makes sense that a cooler running engine should last longer.

If you need to fix or modify one of the above situations, get one, if not, stick with the normal operating temp.
I have one, but I run a Tuner, CIA & LT Headers ALL of which lean me out, so I was running very close to CEL lean. The 180 t-stat brought me back almost to stock A/F specs...

 

nice right up hammer that was very informative BIG +1

 

put that in the faq section maybe?

 

ya but getting people to go un there haaaaaa good luck, maby in a perfect world

 

Actually, newer engines are designed with tight tolerances and are designed to run ar at least 195 for proper sealing and longevity. Running cooler has been proven to cause more engine wear.