The Duramax LMM, which debuted in 2007, was a high-performance diesel engine designed to meet the stringent Federal emissions standards. Despite the challenge, General Motors (GM) was able to produce an engine that not only met the new regulations but also outperformed its predecessor, the LBZ. This blog post will examine the features that make the Duramax LMM stand out and discuss how GM was able to achieve improved performance while complying with the new emissions standards.
The Duramax LMM is a 6.6-liter V8 engine with a block and head made of cast gray iron and cast aluminum, respectively. It delivers 365 bhp at 3200 rpm and a whopping 660 lb-ft of torque at 1600 rpm, thanks to the injection system that uses Bosch High Pressure Common Rail with CP3.3 Injection Pump. These impressive performance figures were achieved by adding an even more efficient variable-geometry turbocharging system and employing additional combustion and exhaust control. The LMM also has an increased-capacity cooling system and uses low-ash engine oil (CJ-4).
To meet the new emissions standards, the Duramax LMM was equipped with an aftertreatment system that included a diesel particulate filter (DPF). This DPF helps to lower particulate (soot) emissions and incorporates a variety of sensors that monitor the system and initiate the regeneration sequence periodically. Additionally, the engine has a cooled (enhanced) exhaust gas recirculation (EGR) system and closed crankcase ventilation that reduces nitrogen oxides (NOx) emissions. The LMM also has new engine control software that optimizes performance while minimizing emissions.
The LMM was produced from mid-2007 until the start of the 2011 calendar year and was the only Duramax offered for model years 2007–2010. Notably, the millionth Duramax V8 engine built was an LMM, assembled in April 2007. While the LMM may no longer be in production, its legacy lives on as a high-performance diesel engine that met stringent Federal emissions standards.