a friend has the A26 in a dump truck and it has been pretty good.
MaxxForce 13 was the same engine, engine is fine. It just wasnt a good idea to force feed an engine its own sh*t like Navistar wanted.
A high temperature combustion produces little soot and is therefor more complete and efficient. It just causes oxygen to bond with the 75% nitrogen in the air around us, making nitrous oxides.
With EGR you get air with less available oxygen within the same air mass, resulting in lower combustion temperatures, more soot and lower efficiency. So EGR+DPF, there is a point at which the balance turns very unfavourable for the DPF because the EGR makes the engine produce more and more soot, resulting in clogging up of the EGR system and VGT turbo itself.
Well, everybody else realised they were nearing that point and adopted DEF to take care of the nitrous oxides outside of the combustion chamber in order to optimize their in-cylinder combustion process for an efficient, low soot burn, yet Navistars CEO demanded his team to go beyond that point and even sued the EPA for approving DEF. The results, we all know.
Scania, for certain emission stages, offered both an EGR+DPF version, as well as a DEF version to give the customer a choice. Later they couldnt manage without both, but their latest versions no longer have EGR and sometimes not even DPF.
Ah, i sound like i am promoting the S13 engine: From an engineering point of view, their marketing talk is correct though.
11 years ago i had the same talk with the John Deere sales rep who was trying to talk me into a Deere Tier 4 Final engine with twin turbos EGR coolers throttle valves, in order to pump 30% EGR back into an engine, while FPT had the same responsiveness with a plain old wastegated turbo and DEF.
So, for once, International isnt lying to cover their ass
Born from a global collaboration of industry powerhouses, the S13 is the lightest 13-liter diesel engine available in North America.
www.internationaltrucks.com