Originally Posted by jamesb0
The spark plugs will not make the truck jump off the line but they do help burn the fuel faster and efficiently, so you might get 1 more mile to the gallon. Lowing the temperature by 15º helps from loosing HP. A little here a little there and before you know it You are going longer between pumps.
Lets say you improve by 5 mpg. 30 x 5 = 150 more miles to a tank.
The hemi is already efficient at burning the air fuel mixture those plugs will do nothing for fuel mileage.
As far as improving the mileage up to 5 MPG........ well that there is just to funny never will happen.
Putting in a lower thermostat doesn't improve fuel mileage at all if anything it hurts it. The computer dumps more fuel at a lower temp, thats why people do it to richen the mixture alittle on an already to lean motor.