The Isuzu/GM Duramax V8 diesel engine has been a popular choice for truck owners due to its power, reliability, and efficiency. The 6.6L LML (VIN code "8") is the 2011–2016 version of the engine and is considered the most advanced Duramax engine produced by GM to date.
The LML Duramax engine was designed to meet new federal emission standards for diesel engines, which required a drastic reduction in engine emissions. The engine uses new 29,000 PSI piezo injectors and a complete fuel system-hardening to tolerate up to 20% biodiesel mixtures. The addition of urea injection, with a 5.3-gallon urea tank, reduces nitrogen oxides and helps the engine comply with the new emission standards. The LML engine also has a fuel injector in the exhaust tract that allows raw fuel injection during the particulate filter recycling routine.
The LML Duramax engine improved upon the fuel efficiency of the LMM Duramax engine. According to Chevrolet, the LML boasted 11% better fuel economy over the previous generation Duramax. The engine achieves this through better oil flow control and oil pump design, resulting in improved temperature control and enhanced durability.
The LML Duramax engine added 30 horsepower and 100 lb-ft of torque over the LMM Duramax engine. The LML engine is rated at 397 hp at 3000 rpm and 765 lb⋅ft of torque at 1600 rpm. The engine block casting is made of new, improved materials, and oil film thickness was increased by changing the main bearings' profiles. A new oil pump was introduced with greater flow to improve lubrication and cooling, increasing pressures at slower speeds. The Duramax trucks also gained an exhaust brake for the first time, using a variation of the Garrett G3788VA Variable Vane Turbo. The LML Duramax engine uses a CP4.2 pump and Piezoelectric injectors, providing a new fuel injection system supplied by Bosch.
The LML Duramax engine has a heavily altered derivative of the LMM engine, with 60% newly designed components. The engine also uses a "9th injector," a fuel injector dedicated solely to introducing fuel into the exhaust stream during active regeneration cycles, which reduces fuel dilution and eliminates the cylinder washing concerns present in the LMM engine.
The LML Duramax engine improved upon the LMM Duramax engine, meeting new federal emission standards and providing a more efficient and powerful engine. The engine block casting, new oil pump design, higher strength pistons and connecting rods, and improved main bearing design were among the key improvements. The LML Duramax engine is considered the most advanced Duramax engine produced by GM to date, and its legacy continues to inspire further improvements in diesel engine technology.