I have a 2004 40 ft diesel pusher with a cat c7 rated at 330 hp. I am not sure what the difference is in this engine when compared to the previous years pre c7 cat 7.2 liter engines. Does anyone know what differences are? I have heard that part of the difference is that the epa required cat to reduce the timing to reduce n02 emissions. Reducing timing would I think reduce mileage. Does anyone know if this is true and has anyone had both engines for comparison?
2004 QDH 40ft Phaeton, Blue Ox Tru-Center
Ham Call N4HWL, TS performance mp-8
First, most 2004 coaches do NOT have C7's. The C7 replaced the 3126 beginning with ENGINE PRODUCTION as of 1/1/04 to meet the new stiffer EPA emissions requirements.
Most chassis makers bought ahead as the earlier engines were less expensive (just as happened on 1/1/07 when the standards got even stricter).
Most C7's (not all) in RV applications were rated at 350 HP.
Best advice is to call the Caterpillar RV Hotline with your engine serial number: 877 777-3126.
And I do not know all the mechanical/electronic changes between 03 and 04 engines-- I suspect quite a lot of that information is proprietary. Few manufacturers will ever tell their competition how they controlled emissions. I suspect it was a number of things, not just one thing.