This is the info I got when I bought our LBZ.
* Cylinder block casting and machining changes strengthen the bottom of the cylinder bores to support increased horsepower and torque
* Upgraded main bearing material increases durability
* Revised piston design helps lower compression ratio to 16.8:1 from 17.5:1
* Piston pin bore diameter increased for increased strength
* Connecting rod “ I ” section is thicker for increased strength
* Cylinder heads revised to accommodate lower compression and reduced cylinder firing pressure
* Maximum injection pressure increased from 23,000 psi to more than 26,000 psi
* Fuel delivered via higher-pressure pump, fuel rails, distribution lines and all-new, seven-hole fuel injectors
* Fuel injectors spray directly onto glow plugs, providing faster, better-quality starts and more complete cold-start combustion for reduced emissions
* Improved glow plugs heat up faster through an independent controller
* Revised variable-geometry turbocharger is aerodynamically more efficient to help deliver smooth and immediate response and lower emissions
* Air induction system re-tuned to enhance quietness
* EGR has larger cooler to bring more exhaust into the system
* First application of new, 32-bit E35 controller, which adjusts and compensates for the fuel flow to bolster efficiency and reduce emissions
The DURAMAX 6600 also has a new intake air heater to reduce smoke and emissions during cold or light-load driving. The system features a 1000-watt grid heater located in the air intake duct, which is triggered automatically by the engine controller. It heats up the incoming air to speed warm-up of the engine.
In addition 50 more horsepower and 45 more lb-ft of torque in the Silverado and Sierra