F450 vs Ram 3500 DRW tow vehicle

4x4ord wrote:

ShinerBock wrote:

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.

40% of what an engine is capable of producing a a certain rpm is definitely a light load.... of course it's a light load .... it's only a 40% load.:S

I thought the rpms we were talking about were 1,600 and 2,000 rpm, not 2,800 rpm? The PSD may make 475 hp at 2,800, but not at the rpms you and Grit dog were talking about. As you said earlier,the max amount of power the PSD makes at 1,600 rpm is 320hp and 380 hp at 2,000 rpm. Even less in the real world. So at these rpms, you are asking for more than 40% of what the engine is capable of giving you at these engine speeds.