I'm new to the diesel crowd, so bear with me. I know that Dodge changed the 5.9 CTD in 2004 and came out with the HO at that time. What's the difference between the earlier common rail engines and the later HO version?

 

The common rail 5.9 Cummins came out in 03 and 04 model years with an HO and a SO version. SO was for California and certain other emission restrictive states.


Starting on 1-1-04 the 04.5 Trucks came with a 50 state compliant engine. The engines include electronic wastegated turbos, 4'' exhaust from the turbo all the way back to the tailpipe and some other internal changes. I believe the internal changes had something to do with inconel valves, better pistons with more oil cooling and a bigger computer in the ECM. They also included a catalytic converter for emission purposes. The 04.5 on up trucks also have 3 injection events, instead of 2.

These newer 5.9 engines have been essentially the same through 07 model year.


The new 6.7 Cummins is in the 07.5 trucks and has a diesel particulate filter and other emission stuff on it.