General Motors Duramax Diesel Engine

The Duramax is General Motors’ diesel engine family for large trucks, designed by Isuzu. The 6.6 liter Duramax is produced by DMAX, a joint venture between GM and Isuzu in Moraine, Ohio. This engine was initially installed in 2001 MY Chevy and GMC trucks and has been the engine of choice since that time. In 2006, production at Moraine was reportedly limited to approximately 200,000 engines per year.[1] On May 9, 2007, DMAX announced the production of the 1,000,000th Duramax V-8 Diesel Engine at its Moraine facility.[1]

LG4

The LG4, or Isuzu 6H, is a commercial-grade vehicle engine and is currently operating in over 300,000 Isuzu and GM-built trucks, including the H-Series and T-series vehicles. It is mated to the Allison 3000 and 3500 Series transmissions.

The following trucks use the LG4:

  • Chevrolet T-Series
  • Isuzu F-Series
  • Isuzu H-Series

Specifications

  • Engine type: 7,785 cc (7.785 L; 475.1 cu in) I6 turbo
  • Bore and stroke: 115 mm (4.53 in) x 125 mm (4.92 in)
  • Block / Head: gray iron / cast iron
  • Redline: 2400 rpm
  • Aspiration: Turbocharged & Intercooled
  • Valvetrain: OHC 4-V
  • Compression: 16.0:1
  • Common-rail
  • Power / Torque:

LB7

The LB7 (engine code “1″) was first introduced in 2001 and continued until 2004. It is a 32-valve design with high-pressure common-rail direct injection and aluminum cylinder heads. The most problematic issue with the LB7 are injectors going bad. GM issued a warranty for this and currently injectors and warrantied for 7 years/200,000 miles. The Duramax was on the Ward’s 10 Best Engines list in 2001 and 2002.

The following trucks use the LB7:

Specifications

  • Engine type: 6,599 cc (6.599 L; 402.7 cu in) V8 turbo
  • Bore x Stroke: 4.06 in (103.1 mm) x 3.90 in (99.1 mm)
  • Block / Head: Cast gray iron / Cast aluminum
  • Aspiration: Turbocharged & Intercooled
  • Valvetrain: OHV 4-V
  • Compression: 17.5:1
  • Injection: Direct; Bosch High Pressure Common-rail
  • Power / Torque: 300 bhp (220 kW) @ 3100rpm / 520 lb·ft (705 N·m) @1800 rpm
  • Source: [3]

LLY

The LLY (internally called the 8GF1) (engine code “2″) is a 6,599 cc (6.599 L; 402.7 cu in) turbocharged engine which debuted in 2004 and continued until the end of 2005. It is a 32-valve design with high-pressure common-rail direct injection and aluminum cylinder heads. The LLY was GM’s first attempt to implement emissions requirements on their diesel trucks. To meet this goal they turned to a newly developed Garrett turbocharger with a variable geometry vane system and they installed an Exhaust Gas Recirculation valve or (EGR Valve). Learning from problems with injectors in the previous LB7 GM changed the valve covers to allow access to the injectors without having to remove the valve covers, saving significant labor costs if injector replacement became necessary, and preventing leaked fuel from entering the crankcase, causing oil dilution. Early on problems came forward from customers complaining of severe overheating, and also in some situations blown head gaskets. Initially GM denied that it was a problem, but after it was sued by a consumer group it relented and included overheating and blown head gaskets as a warranted item.

The following trucks used the LLY engine:

Specifications

  • Engine type: 6,599 cc (6.599 L; 402.7 cu in) V8 turbo
  • Bore x Stroke: 4.06 in (103.1 mm) x 3.90 in (99.1 mm)
  • Block / Head: Cast gray iron / Cast aluminum
  • Aspiration: Turbocharged & Intercooled
  • Valvetrain: OHV 4-V
  • Compression: 17.5:1
  • Injection: Bosch High Pressure Common-rail
  • Power / Torque: 310 bhp (230 kW) @3000rpm / 605 lb·ft (820 N·m) @1600 rpm
  • Head casting is 8gf1
  • Block casting is #22351021213
  • Source: [4]

LLY/LBZ

The 2006 LLY (engine code “2″) debuted in the beginning of 2006 and ended production with the start of the 2007 calendar year. Mechanically it is identical to the LBZ and is mated to the new 6 speed Allison transmission however it retained the LLY designation.

The LBZ (engine code “D”) debuted in the earlier part of 2006 and continued into 2007 sold only in the “classic” body style. It has a more powerful tune loaded into the computer that allows it produce more power and torque.

Changes include:

  • Cylinder block casting and machining changes strengthen the bottom of the cylinder bores to support increased power 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 (1,585.8 bar) to more than 26,000 psi (1,792.6 bar)
  • 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”

LBZ applications:

LLY applications:

Specifications

  • Engine type: 6,599 cc (6.599 L; 402.7 cu in) V8 turbo
  • Bore x Stroke: 4.06 in (103.1 mm) x 3.90 in (99.1 mm)
  • Block / Head: Cast gray iron / Cast aluminum
  • Aspiration: Turbocharged & Intercooled
  • Valvetrain: OHV 4-V
  • Compression: 16.8:1
  • Injection: Bosch High Pressure Common-rail
  • Power / Torque: