Cat vs Powerstroke torque curves

rjstractor wrote:
The industrial or OTR diesels are also designed to run 1,000,000 miles or more at a full power duty cycle. The PSD and others could have similar duty ratings but their power ratings would be reduced, probably to half what they are in a pickup. Even in the F650 its power rating is reduced to only 330/725. Similarly, a Cummins ISB in a Freightliner M2 has a max rating of 325/750, with ratings as low as 200/520. To have a million mile full power duty rating, those engines would likely need to be limited to about that 200/520 rating.

The peak power rating of the Powerstroke might not affect its life nearly as much as you think. Many industrial machines and some highway tractors can work all day long in conditions where they require nearly 100% of their engines rated power output. The Cat engine makes its peak power of 335 hp at 2000 rpm. At the low end of it working range, 1200 rpm, it is still able to deliver 285 hp or 85% of its peak power output. Even though the Powerstroke has a max power out of 440 hp it almost never generates that kind of power. With your foot in it pulling a heavy RV you are seldom at rpms above 1900. You can see from the graph that @ 1900 rpm and full throttle the Powerstroke is only capable of making about 900 lb ft of torque which equates to 325 HP. At 1500 rpm the Powerstroke might be capable of making about 825 lbft of torque or 235 hp which is just 53% of its rated power output. Just casually cruising down the highway with a 15000 lb trailer in tow only requires about 100 hp.