Originally Posted by oakaro68
So it appears from my endless and less than scientific "research", dpf might not cause as much wear as egr, might this be correct? Any more pre/post uoa anyone want to share?
I think you really mean "SCR might not cause as much wear as EGR", since those are the two that are an either/or, both used to reduce NOx. DPF is present with either one, but does have to work a lot harder and regenerate more often when used with high-dose EGR than when used with SCR. SO if that's what you meant, then I'd say its unquestionably correct that SCR is less damaging to the engine than high-dose EGR to meet NOx requirements.
DPF in and of itself isn't particularly harmful to the engine, especially if DPF regeneration is implemented with a "7th injector" in the exhaust plumbing rather than injecting into a cylinder on the exhaust stroke. SCR also happens downstream of the turbo and doesn't directly affect the engine. EGR, on the other hand, basically snuffs out complete combustion in the cylinder, trading higher CO and particulates for lower NOx, and then over-working the DPF and oxidation catalyst to clean up the mess it made. Plus it demands an EGR cooler to with all the attendant problems that come with those (higher load on the cooling system, boiling coolant in the cooler and cooking abrasive additives out of the coolant, clogging the cooler with carbon on the exhaust side, etc.). At least DPF with SCR moves ALL the monkey-business downstream of the turbo. About the only negative effect the little SCR/DPF chemical plant in the exhaust plumbing can have (directly) on the engine is higher backpressure, and that's not nearly as directly damaging as the huge increase in particulates from high-dose EGR, and the fuel dilution and higher exhaust temps from exhaust-stroke injection for DPF regen. Those things were band-aid solutions from day 1.
