Duramax V8 engine

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Duramax Diesel engine
Manufacturer DMAX (General Motors/Isuzu)
Production 2001 – present;
Predecessor 6.2 and 6.5 L Detroit Diesel

The Duramax is a General Motors V8 diesel engine family for trucks. The 6.6-liter Duramax is produced by DMAX, a joint venture between GM and Isuzu in Moraine, Ohio. The Duramax block and heads are poured at The Defiance GM Powertrain foundry in Defiance, Ohio. This engine was initially installed in 2001 Chevrolet and GMC trucks, and has been an option since then in pickups, vans, and medium-duty trucks. 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 at its Moraine facility.[1]

Duramax LML

Engine RPO Codes[edit]


RPO LB7 (engine code "1") was first introduced in 2001 and continued until early-2004. It is a 32-valve design with high-pressure common-rail direct injection and an experimental composite design cylinder head. The most common issue with the LB7 is injector failure, so common that a special policy bulletin was issued (#04039B). Fuel leaked and entered the crankcase, causing oil dilution. Early on, customers came forward complaining of severe overheating, and in some situations, blown head gaskets. Initially GM denied it was a problem, but after being sued by a consumer group, GM relented and included overheating and blown head gaskets as a warranted item.

The following trucks use the LB7:


  • Engine type: 6,599 cc (402.7 cu in) V8 turbo
  • Bore x Stroke: 4.06 in (103 mm) x 3.90 in (99 mm)
  • Block / Head: Cast Iron / Aluminum
  • Aspiration: Turbocharged & Intercooled
  • Valvetrain: OHV 4-V
  • Compression: 17.5:1
  • Injection: Direct; Robert Bosch GmbH high pressure common-rail
  • Power / Torque: 300 hp @ 3,100 rpm 520 lb-ft @ 1,800 rpm

The LLY was introduced in 2004 and replaced the LB7 completely mid-year


The LLY (internally called the 8GF1) (engine code "2") is a 6,599 cc (402.7 cu in) turbocharged engine which debuted in mid-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 installed an 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.

The following trucks used the LLY engine:



  • Engine type: 6,599 cc (402.7 cu in) V8 turbo
  • Bore x Stroke: 4.06 in (103 mm) x 3.90 in (99 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: 305 bhp (227 kW) @3000 rpm / 605 lb⋅ft (820 N⋅m) @1600 rpm
  • Head casting is 8gf1
  • Block casting is #22351021213


There are two VIN codes for the LBZ. The first is VIN 2. While it is the LBZ it has LLY tune tables.

Second is VIN D. This was introduced in 2006 and continued into 2007 sold only in the "classic" body style. It has an improved engine computer tune that produces increased power and torque over the 2005 LLY version of the motor. First appearance of the Duramax in the Express/Savanna vans. The LBZ is regarded as the best Duramax ever made[citation needed].

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 lowers 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:



  • Engine type: 6,599 cc (402.7 cu in) V8 turbo
  • Bore x Stroke: 4.06 in (103 mm) x 3.90 in (99 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:
Code Years Power@rpm Torque@rpm Redline (rpm)
LBZ (Chevrolet Silverado 2500HD / 3500 Classic (auto trans), GMC Sierra 2500HD / 3500 Classic (auto trans)) 2006–2007 360 bhp (270 kW) @3200 650 lb⋅ft (881 N⋅m) @1600 3450
LLY (Chevrolet Kodiak Medium Duty (LRX option), GMC TopKick Medium Duty (LRX option), Hummer H1 Alpha) 2004–2005 300 bhp (220 kW) @3000 520 lb⋅ft (705 N⋅m) @1600 3200
LBZ(Chevrolet Kodiak Medium Duty (LPD option), GMC TopKick Medium Duty (LPD)) 2006–2007 300 bhp (220 kW) @3000 605 lb⋅ft (820 N⋅m) @1600 3200
LLY (Chevrolet Express, GMC Savana) 2006–2007 250 bhp (190 kW) @3200 460 lb⋅ft (624 N⋅m) @1600 3450


The LMM (engine code "6") debuted part way through 2007 and ended production with the start of the 2011 calendar year and is mated to the 6-speed Allison transmission. The LMM was the only Duramax offered for model years 2007–2010.[3] A version was used in the Trident Iceni.[4]



  • Engine type: 6,599 cc (402.7 cu in) V8 turbo
  • Bore x Stroke: 4.06 in (103 mm) x 3.90 in (99 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 with CP3.3 Injection Pump
  • Power / Torque: 365 bhp (272 kW) @3200 rpm / 660 lb⋅ft (895 N⋅m) @1600 rpm
Code Years Power@rpm Torque@rpm Redline (rpm)
LML (Chevrolet Silverado HD, GMC Sierra HD) 2011–2016 397 bhp (296 kW) @3000 765 lb⋅ft (1,037 N⋅m) @1600 3450
LMM (Chevrolet Silverado HD, GMC Sierra HD) 2007–2010 365 bhp (272 kW) @3200 660 lb⋅ft (895 N⋅m) @1600 3450
LMM (Chevrolet Kodiak Medium Duty (LYE option), GMC TopKick Medium Duty (LYE option)) 2007–2010 330 bhp (250 kW) @3000 620 lb⋅ft (841 N⋅m) @1600 3250
LMM (Chevrolet Kodiak Medium Duty (LRX option), GMC TopKick Medium Duty (LRX option)) 2007–2010 300 bhp (220 kW) @3000 520 lb⋅ft (705 N⋅m) @1600 3250
LMM (Chevrolet Express, GMC Savana) 2007–2010 250 bhp (190 kW) @3200 460 lb⋅ft (624 N⋅m) @1600 3450
LMM (Chevrolet Express, GMC Savana) 2011–2016 260 bhp (190 kW) @3100 525 lb⋅ft (712 N⋅m) @1600 3450

Emission controls:

  • Additional combustion control, including an even more efficient variable-geometry turbocharging system, cooled (enhanced) exhaust gas recirculation (EGR) and closed crankcase ventilation to reduce nitrogen oxides (NOx)
  • Additional exhaust control, including oxidizing catalyst and new diesel particulate filter (DPF) to reduce soot and particulate matter
  • Increased-capacity cooling system
  • New engine control software
  • Use of low-ash engine oil (CJ-4)



The 6.6L Duramax diesel engine (VIN code "L") is used on 2010 interim and 2011 Chevrolet Express and GMC Savana vans and 2011 Chevrolet Silverado and GMC Sierra trucks with RPO ZW9 (chassis cabs or trucks with pickup box delete). The LGH engine is rated at 335 bhp (250 kW) at 3100 rpm and 685 lb⋅ft (929 N⋅m) at 1600 rpm. Similar to the LML this engine also uses a DPF and DEF system to meet emission standards.


The 6.6L RPO LML (VIN code "8") is the 2011–2016 version of the Isuzu/GM Duramax V8 diesel engine. It is a further advanced version of the LMM engine with the majority of the changes addressing a required drastic reduction in engine emissions. Some mechanical aspects of the engine, such as piston oil flow design for improved temperature control and oil pump design, were also improved to enhance durability even further.

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 5.3 gallon urea tank are updating the fuel and emissions systems. This engine has a fuel injector in the exhaust tract, to allow raw fuel injection during the particulate filter recycling routine. The RPO LML engine is rated at 397 horsepower (296 kW) at 3000 rpm and 765 lb⋅ft (1,037 N⋅m) of torque at 1600 rpm.[8]


The L5P duramax is the latest version of the Duramax V8 diesel engine.(engine code Y) Introduced in the 2017 model year it is the most powerful diesel engine GM has produced with 445 hp @ 2,800 rpm and 910 lb-ft @ 1,600 rpm. Design spec performance can exceed 550 bhp @ 3050 rpm and 1050 lb-ft at 1975 rpm.


Although touted as one of the most important new engine concepts by delivering a diesel that is both capable and compact, this engine is not yet commercially launched. The engine project is currently on an indefinite hold.[9] GM planned a 4.5L 72-degree V8[10] for light-duty applications which would be built at GM's powertrain facility in Tonawanda, New York after 2009. Designed to fit in the same space as an LS engine, it is expected to produce over 310 bhp (230 kW) and 520 lb⋅ft (705 N⋅m) of torque while delivering 25% better fuel efficiency than a gasoline equivalent. An electronically controlled, 29,000-psi (2,000 bar) common-rail fuel system is also used on the engine with an ability to inject fuel five times per combustion event.[11] It was initially targeted for the Chevy Silverado/GMC Sierra and Hummer H2.[12] Unlike previous Duramax engines, the 4.5-liter is planned to be designed and built entirely by GM without assistance from Isuzu.[13]

See also[edit]


  1. ^ a b "GM celebrates one-millionth Duramax diesel". Archived from the original on May 14, 2007. Retrieved May 9, 2007.
  2. ^ a b 2007 LLY LBZ spec sheet[permanent dead link]
  3. ^ DuramaxHub (2016). "Duramax Engine Identification: Duramax Engine ID by VIN number". Retrieved 14 December 2016.
  4. ^ Korzeniewski, Jeremy (20 August 2008). "Trident diesel sports car not vaporware, still sounds too good to be true". Autoblog. Retrieved 14 December 2016.
  5. ^ GM Media. "2007 Chevrolet Silverado 3500HD Specifications". Retrieved 14 December 2016.
  6. ^ 2009 GMC Sierra HD engine curve[permanent dead link]
  8. ^ General Motors (10 March 2010). "GMC's 2011 Heavy-Duty Trucks Build On Proven Strong Heritage With New Duramax 6.6L Turbo Diesel Engines".
  9. ^ Colin Mathews (11 March 2009). "Chevy Puts Baby Duramax On Hold Until Further Notice".
  10. ^ "2010 Duramax 4500 Diesel".
  11. ^ Neff, John (5 May 2008). "GM releases details on upcoming 4.5L Duramax turbo-diesel V8". Autoblog. Retrieved 14 December 2016.
  12. ^ Neff, John (15 June 2007). "GM announces new 4.5L V8 Duramax diesel for half-ton trucks and HUMMER H2". Autoblog. Retrieved 14 December 2016.
  13. ^ Levine, Mike (2007-06-15). "GM Announces Production of New 4.5-Liter Duramax Diesel V8 for Light Duty Pickups". PickupTruck.com. Retrieved 2007-06-21.

External links[edit]