General Motors light and medium diesel trucks use the Duramax engine, which is produced by Duramax. This engine has a 32 valve design with aluminum cylinder heads. It also has a high-pressure common rail direct injection system. The Duramax diesel engine is extremely efficient compared to a gasoline engine, by 25%. The pollutants and emissions are also lower.
The LML engine was significantly updated for 2011 to provide improved exhaust emissions that comply with the new federal emission standards for diesel engines, provide better engine rigidity and further noise reduction. New 29,000 PSI piezo injectors, a complete fuel system-hardening to tolerate up to 20% biodiesel mixtures and urea injection (to reduce Nitrogen oxides) with a 5.8-gallon urea tank are updating the fuel and emissions systems.
This engine also has now 9 fuel injectors, one directly injecting in the exhaust tract, to allow raw fuel injection during the particulate filter recycling routine. This was previously accomplished by running raw fuel through the engine via the engine fuel injectors without igniting the fuel (valves were kept open), but risks of washing down cylinder walls and causing engine damage are increased with the use of Biodiesel.