29 August 2006

New V-8 diesel. General Motors (GM) announced it will introduce a new V-8 turbo-diesel for North American light-duty trucks after 2009.

The new dual-overhead cam, four-valve V-8 diesel engine will fit within the same space as a small-block V-8 gasoline engine. The compact size is made possible by using an integrated air system and narrow block.

The new diesel engine will meet the EPA Tier 2 Bin 5 and the California LEV II emission standards, thus qualifying for sale in all 50 states. The engine will use a diesel particulate filter as well as NOx aftertreatment. The type of NOx aftertreatment—NOx adsorbers or urea-SCR—was not disclosed.

Technical highlights of the engine include aluminum cylinder heads with integrated manifolding, compacted graphite iron (CGI) engine block and fracture-split main bearing caps and connecting rods. A high pressure, common-rail fuel system is used, which has the ability to inject fuel five times per combustion event to control noise and emissions.

2007 Duramax. GM also announced a new version of its Duramax 6.6L V-8 turbo-diesel, featuring upgrades to the engine and a diesel particulate filter. The engine complies with the 2007 emission standards for heavy-duty diesel engines which require a 90% reduction in particulate matter and 50% reduction in NOx emissions.

The new Duramax 6.6L V-8 (LMM) engine is available in two versions, with 300 hp and 520 lb-ft of torque, as well as a new 330 hp option with 620 lb-ft of torque. Final advertised ratings for the Chevrolet Silverado and GMC Sierra 2500 and 3500 HD pickups and GM’s full-size vans will be released later this year.

The DPF uses a two stage DOC-DPF architecture with active regeneration support. While few details were released on the regeneration strategy or its implication to the vehicle users, GM said that “the regeneration process uses heat to burn off the soot and, in most cases, is performed automatically. An onboard computer controls fuel injection and oxygen content to adjust the exhaust energy to the appropriate level to clean the particulate trap. Periodic servicing of the filter is required to remove accumulated ash.”

The new Duramax diesel features a number of engine enhancements:

  • Cylinder block casting and machining changes
  • Upgraded main bearing material
  • Revised piston design lowering compression ratio from 17.5:1 to 16.8:1
  • Revised cylinder heads to accommodate higher peak cylinder firing pressure
  • Maximum injection pressure increased from 23,000 psi (159 MPa) to more than 26,000 psi (179 MPa)
  • Fuel delivered via higher-pressure pump, fuel rails, distribution lines and all-new, seven-hole fuel injectors
  • Improved glow plugs heat up faster through an independent controller
  • Revised variable-geometry turbocharger, operating at up to 120,000 rpm, delivering a maximum boost of 20 psi (0.14 MPa)
  • Re-tuned air induction system for quieter operation
  • EGR with a larger cooler to provide for cooler exhaust gases going into the system
  • First application of new, 32-bit E35 engine controller

Source: General Motors