Are the Cummins torque specs useful for engines?

The torque output specifications for Cummins diesel engines are useful for comparing overall power output between a particular Cummins engine and another engine, with higher-torque engines producing more power. However, the performance of an engine once installed in a vehicle depends heavily on that vehicle's specific features.

The same Cummins diesel engine with a manufacturer-specified torque output can have a different actual output when installed in one type of vehicle versus another. For example, the 6.7-liter Cummins diesel used in the 2015 RAM 3500 pickup truck has a torque output of 800 foot-pounds when paired with an automatic transmission, but it decreases to a maximum torque of 660 foot-pounds in a manual-transmission truck to avoid exceeding the structural capacity of the manual transmission system.