In order to meet ever-increasing emission standards and keep up with the Joneses (at the time, Ford’s upcoming 6.7L Power Stroke), GM amended the Duramax once more for the 2011 model year. The fifth generation common-rail V8 was given the RPO code LML. While it was nothing like a full redesign—it still displaced 6.6L, used a cast-iron block with aluminum heads and sported a 16.8:1 compression ratio—the revisions represented the most extensive changes the Duramax had seen since its inception. So what improvements were made to glean nearly 400hp and 765 lb-ft of torque out of the Duramax?
The LML Duramax was released for 2011 model General Motors & Chevrolet HD trucks. The latest version of the 6.6L Duramax requires advanced emissions equipment, including the use of diesel exhaust fluid injection, to reduce nitrogen oxide emission levels by 63 percent over LMM powered trucks. This allows the LML to exceed currently mandated federal emissions requirements and potentially meet future requirements as well. The LML was replaced for the 2017 model year by the next generation Duramax L5P.