Found this elsewhere online:
Gary Arvan, Duramax chief engineer, said 90 percent of the engine is new.
... nearly every other system, from the oil pan to the fuel injectors, has been re-engineered and “designed to produce more torque at lower rpm,” said Arvan.
Arvan said the revamped Durmax engine has three unique features:
• Remelted piston bowl rims: The center section of each aluminum piston is heated up again after casting. That changes the molecular structure of the aluminum, making it better able to withstand heat.
• A venturi jet drain oil separator: It filters oil mist out of the blow-by gases and returns the oil to the sump.
• Closed loop glow plug temperature control: It uses sensors to manage the glow plugs to provide instant starts in cold weather.
Other changes to the Duramax include:
• A new, stronger block, redesigned aluminum cylinder heads and a new crankshaft with improved bearing surfaces;
• A new fuel system, with proprietary GM controls; and
• An electronically controlled turbocharger mounted between the cylinders.
Arvan said the new version of the Duramax produces 35 percent less oxides of nitrogen, or NOx, and will only need minor emissions systems revisions in the coming years to stay ahead of toughening clean air standards.