#Service def system speed limited upgrade#

A concerned Ford quickly acted to increase the Power Stroke's available horsepower and torque rating, issuing a free performance upgrade to owners which would re-calibrate the engine to the tune of 400 horsepower and 800 lb-ft. General Motors blindsided Ford with the release of these figures, which were revealed shortly after Ford's 390 hp/735 lb-ft 6.7L Power Stroke became available. Rated at 397 horsepower and 765 lb-ft of torque, the engine is significantly more powerful than any prior Duramax. This includes an upgraded engine block casting, oil pump, high strength pistons and connecting rods, main bearing design, and re-routed oil passage circuit. The LML is said to have been engineered using 60% newly designed components not carried over from a previous generation Duramax. GM's official statement is that fuel mileage increased 11% over the previous generation LMM engine. DEF is not particularly costly and owners incur noticeable fuel savings even while factoring in the cost of exhaust fluid. However, this technology actually allows for an advantageous engine calibration to be executed, reducing the duty cycle of DPF regenerations and providing significant improvements in fuel economy. The implementation of the SCR system, which requires a constant supply of diesel exhaust fluid (DEF), was met with heavy scrutiny. The result eliminated cylinder washing concerns and permitted the use of up to B20 biodiesel. This is opposed to the previous generation's (LML) late/post injection technique.

The Duramax LML introduced the '9th injector' system in order to supply fuel to the DPF during regeneration.