Quote:
Originally Posted by mechman600
After the Navistar debacle of 2010+, I believe EPA now has mandated SCR for HD truck engines.
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SCR is mandated per se--it's just basically the only way that's been proven to met the regulated levels. That being said, the '07.5 Cummins in the Dodge met 2010 emissions levels for the pickup versions. They ran a NOx adsorber but no SCR.
Early on Navistar bet the farm on being able to meet the levels with only EGR. Early on they could. Later on, as the levels came down, they ran more and more EGR and still couldn't get the levels low enough. Basically, they refused to eat crow and admit they were wrong. By that point, the EPA was issuing them a hefty fine for every engine they sold (I think it was around $5,000). The nail in the coffin came when the other manufactures (Volvo, Cummins, etc.) file suit claiming that they should be allowed to sell the engines at all, and recently won the lawsuit. Recently they've been buying engines from Cummins while they get their own engines to work with SCR.