Cooler Thermostat

[djerickd]

Would a cooler running engine perhaps yield better MPG?

[HHOhoper]

All engines are designed to operate within a certain temperature range. I think as long as you are within that range you will see maximized gas mileage. If you are running too hot, your cooling fans will be most likely be on and that will create more draw on your electrical system and the rule of thumb (don't quote me, but I've heard it pretty consistently) is for every 10amps you put on your electrical system, you lose .5 to 1 MPG.
If your engine is running too cold, your A/F ratio will probably run rich because your car will be trying to get itself up to normal operating temperature. I think of the two scenarios, getting too hot is more of a headache than getting too cold is.

My two cents...

[hydrotinkerer]

On OBD1 and OBD2 vehicles if you run a cooler thermostat the vehicle thinks its cold and richens the mixture.

[hhocavalier]

newer cars run hotter then older cars becouse the engine running hotter makes it run cleaner and burn fuel more complete.

[Scooterdog]

newer cars run hotter then older cars becouse the engine running hotter makes it run cleaner and burn fuel more complete.

100% correct. Good to see someone on this board has it together.
ford designed an engine out of ceramic, it could ran much hotter, produced a boat load of power, and could achieve upwards to 27,000 RPM. Wish they would have put that one out. It's lubrication system was the exhaust, kinda cool hu?