F450 vs Ram 3500 DRW tow vehicle

4x4ord wrote:
The rule is the same for all turbo charged diesel engines... throttling down and gearing up for light loads saves fuel. I was listening to some farmers talk about their tractors equipped with IVT (infinitely variable) transmissions. During light load operations the computer slows the engine down below 1200 rpm and some guys over ride the comperter because they can't wrap their head around the idea of working an engine at such low rpm.

For light loads yes, and I have been saying that. However, heavy loads is another issue and utilizing over over 40% of an engines rated power at an rpm isn't a light load placed upon the engine. It is even worse in the real world because rated power is an idealistic environment at 70F, at zero ft of elevation, and low humidity which is how the SAE dynos are done. Realistically, your are not attaining rated numbers most of the time at it is even more of a load being placed on your engine at that rpm.