Quote:
Originally Posted by Daox
I know its not apples to apples, but I was just reading an article in an industrial magazine about off road diesel engines and their latest on hitting tier 4 final emissions. Pretty much every maker is claiming better efficiency despite the new emissions equipment. I also find it hard to believe that the equipment just doesn't work. It obviously goes through a lot of testing and it wouldn't pass the emissions tests if it didn't work.
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As far as the FE goes, it's a tricky comparison to make. Let's way we have 3 scenarios:
1) Older engine, that didn't have to meet strict emissions standards
2) Newer engine, as it comes from the factory, meeting the new standards
3) Newer engine, set up for FE but allowed to exceed the modern strict standards
Now, in many cases, #2 gets equal to slightly better FE than #1. However, this isn't because of the lower emissions per se, but rather because of the additional technology added (i.e., common rail fuel injection, variable geometry turbocharger, etc.). If you just tried to tune #1 to meet the modern standards, the FE would be absolutely horrible. Manufactures didn't add the technology earlier because, while they would have increased the FE of #1, most customers wouldn't be willing to pay for the additional cost. Now #3 gets much better FE than #1, because it has all the additional technology, but not the emissions constraints.
As far as the reliablility goes, I think euromodder might have overstated it a little bit, but he's absolutely correct that when EGR & DPF's first came out there were serious, serious issues with reliablity (mine was the first year). After a few years, the reliablity has come a long way. At least for the typical person. Keep in mind that the systems are designed for "normal" duty cycles. When you start driving efficiently and "non-normal" problems can often arise--most commonly due to the fact that the aftertreatment needs to stay quite hot to be effective, and driving efficiently lowers the amount of heat sent into the exhaust.
It's not really that different than what the gasoline world went through years ago with catalytic converters, electronic fuel injection, etc. Some of the first models had some serious issues, but most were worked through in a few years.