Most non Chevy Diesel drivers have no idea what the Duramax nomenclature alphabet soup is all about. Heck, even a lot of Duramax drivers and fans don’t have any idea what the difference between an LB7 and an LML is. This article will detail the differences, break down of years and specs. Here’s to learning something new- Cheers! Diesel Tees

 

 

The Duramax is General Motors diesel engine family for light- and medium-duty 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 model year Chevy 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.

Engine RPO Codes

LB7

RPO LB7 (engine code “1″) was first introduced in 2001 and continued until mid 2004. It is a 32-valve design with high-pressure common-rail direct injection and a experimental composite design cylinder head. The most problematic issue with the LB7 is injector failure. Fuel leaked and entered the crankcase, causing oil dilution. Early on customers came forward complaining of severe overheating, and also 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. GM issued a warranty for this after the fact for injectors, which now have 7 year/200,000 mile coverage. The Duramax was on the Ward’s 10 Best Engines list in 2001 and 2002.

The following trucks use the LB7:

• Chevrolet Kodiak/GMC Topkick
• Chevrolet Silverado/GMC Sierra HD

Specifications

• Engine type: 6,599 cc (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:

LLY

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 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.

The following trucks used the LLY engine:

• 2006 Hummer H1 Alpha
• Chevrolet Silverado/GMC Sierra HD

Specifications

• Engine type: 6,599 cc (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: 305 bhp (227 kW) @3000rpm / 605 lb·ft (820 N·m) @1600 rpm
• Head casting is 8gf1
• Block casting is #22351021213
• Source:

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 late 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:

• Chevrolet Silverado HD
• Chevrolet Kodiak
• GMC Sierra HD
• GMC TopKick

LLY applications:

• Chevrolet Silverado HD
• Chevrolet Kodiak
• GMC Sierra HD
• Chevrolet Express full-size (reduced power output mated to a 4L85E transmission)
• GMC Savana full-size (reduced power output mated to a 4L85E transmission)

Specifications

• Engine type: 6,599 cc (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:

 

LMM

(Diesel Oxidizing Catalyst) where the fuel is burned to elevate the temperature of the exhaust. This hot exhaust flows into the DPF and burns the trapped soot.

A version was used in Trident Iceni.

Specifications

• Engine type: 6,599 cc (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 with CP3.3 Injection Pump
• Power / Torque: 365 bhp (272 kW) @3200rpm / 660 lb·ft (895 N·m) @1600 rpm

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)

Applications:

• 2007- Chevrolet Silverado HD[7]
• 2007- GMC Sierra HD
• Chevrolet Kodiak
• GMC Topkick
• Chevrolet Express/GMC Savanna

LMK

This engine is not yet commercially launched although it was touted in the automobile press as one of the most important new engine concepts for small trucks and SUVs by finally delivering a capable diesel engine in a compact enough package. The engine project is current on indefinite hold by GM. General Motors planned a 4.5 litre 72-degree V8 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 a Chevrolet Small-Block engine, it is expected to produce over 310 bhp (230 kW) and 520 lb·ft (705 N·m) of torque. It added urea injection, 29,000-psi (2,000 bar) piezo-electric common-rail fuel system over previous Duramax architecture.

It was initially targeted for the Chevy Silverado/GMC Sierra and Hummer H2.[10] Unlike previous Duramax engines, the 4.5 liter is planned to be designed and built entirely by GM, without assistance from Isuzu.

As of March 2009, a GM spokesperson stated the engine project has been put on an “indefinite hold” due to current economic conditions.

LML

The 6.6L RPO LML (VIN code “8″) is the latest version (2011 – present) of the Isuzu/GM Duramax V8 diesel engine and actually 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 5.8 gallon urea tank are updating the fuel and emissions systems. This engine also has now 9 fuel injectors, one directly injecting in the exhaust tract, to allow raw fuel injection during the particulate filter recycling routine. The RPO LML engine is rated at 397 horsepower at 3000 rpm and 765 lb.-ft. of torque at 1600 rpm.

 

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LGH

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.

Source http://en.wikipedia.org/wiki/Duramax_V8_engine

 

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