F450 vs Ram 3500 DRW tow vehicle

4x4ord wrote:
^^^^ Nebraska tractor tests has tested hundreds of turbo charged diesel engines and have reported that all obtain better fuel economy by throttling down and gearing up under light load conditions.

Running the Powerstroke at 2000 rpm would qualify as throttling down but if you notice the article defines a light load as one that requires less than 65% of an engine's peak Hp. So for the 2020 Ford that means a light load would be a load requiring under 308 hp. At a light load such as that, the article says reduce rpm by 20 to 30%. So in other words if the F450 is pulling a light load .... say one that requires under 300 Hp... it would be good to throttle it back to between 1820 and 2080 rpm. If I was towing loads that require 300 hp I'd want the 4.30 gears.

Not necessarily, A Powerstroke and Cummins 6.7L are made for a completely different purpose and have completely different cam profiles than that of a tractor. Most tractors like our John Deere 4430 is tuned/design for low rpms so its cam profile is made so that it makes peak power and efficiency at lower rpms and low speeds. Similar to this 4.5L chart below.



The PSD and CTD on the other hand are made for higher rpms and higher speeds so the cam profile was made for better efficiencies in these higher ranges. Not only that, but their turbo efficiency maps are as well. You are using engines designed for a totally different purpose and saying it applies to on road engines.