The LLY is indicative of the Duramax’s towards meeting strict emissions requirements in the U.S. while keeping the engine competitive in the market.The 2004 LLY was the first Duramax to utilize exhaust gas recirculation (EGR) and a variable vane turbocharger (VVT). The Garrett VVT provided noticeably favorable performance characteristics in comparison to the LB7’s IHI fixed geometry turbo. For the 2006 model year, the LLY underwent minor changes, yielding an 85 lb-ft improvement over the 2004/2005 model. These changes are perceived to have been made in preparation to meet future emissions requirements as well as increase torque output to maintain a competitive edge. 2006 would make the last year for the LLY, but the next generation would build upon the changes made to the Duramax platform.
The Duramax LLY phased out the LB7 during the 2004 model year and continued production until 2006. For the 2007 model year, the next generation LBZ would take over entirely. LLY’s were available in Chevrolet Silverado HD, GMC Sierra HD, Hummer H1, Chevrolet Kodiak, and GMC TopKick models (the Kodiak and TopKick being medium duty trucks in GM’s lineup). The LLY was the first emissions controlled Duramax and available mated to the Allison 1000 automatic (5 speed for 2004/2005 model years, 6 speed for 2006 model year) or the ZF 6 speed manual transmission.


Engine: 6.6L Duramax LLY, 90 degree V8 diesel
Years Produced: 2004 – 2006
VIN Code: 2 (8th digit of VIN)
Displacement: 403 cubic inches, 6.6 liters
Assembly Site: DMAX engine plant, Moraine, Ohio
Head/Block Material: Aluminum cylinder heads, cast iron engine block
Compression Ratio: 17.5 : 1 (2004 & 2005 model years), 16.8 : 1 (2006 model year)
Minimum Cylinder Pressure: 300 psi (minimum compression test pressure)
Firing Order: 1-2-7-8-4-5-6-3

Duramax diesel cylinder numbers

Bore: 4.055″ (103 mm)
Stroke: 3.897″ (99 mm)
Aspiration: Turbocharged and intercooled – Garrett GT3788VA variable vane turbocharger (VVT), air-to-air intercooler
Injection: Direct injection, 23,000 (26,000 for 2006 MY) psi high pressure common rail with Bosch CP3 injection pump
Valvetrain: OHV (overhead valve), 4 valves per cylinder
Oil Capacity: 10 quarts w/ filter
Engine Weight: Approx. 835 lbs
Idle Speed: ~ 680 rpm
Max Engine Speed: 3,250 rpm (rev limiter)
Emissions Equipment: Exhaust gas recirculation (EGR) and diesel oxidation catalyst (DOC)
Peak Horsepower: 310 hp @ 3,000 rpm
Peak Torque: • 520 lb-ft @ 1,600 rpm (2004 & 2005 model years)
• 605 lb-ft @ 1,600 rpm (2006 model year)
Engine Dimensions: Length Width Height
Approx 30″ Approx 30″ Approx 32″