6.6L Duramax LBZ

Duramax LBZ Specs & Info

The LBZ was relatively short lived, having been available for only two model years for no concise reason other than its replacement, the LMM, was capable of meeting stricter emissions regulations rolling into effect near the time of its retirement. Mechanically, the LBZ is nearly identical to the 2006 model year LLY. However, the LBZ features more aggressive engine tuning, yielding a substantial increase in horsepower and torque over its predecessor. The LBZ produced 360 horsepower and 650 lb-ft of torque to the LLY's 310 horsepower and 605 lb-ft. By mid-model year for 2007, the LBZ was effectively replaced by the emissions compliant, diesel particulate filter equipped LMM.

The 6.6L Duramax LBZ's applications included the Chevrolet Silverado HD, GMC Sierra, HD, Chevrolet Kodiak, and GMC TopKick (the Kodiak and TopKick being medium duty truck models. In the aftermarket, the LBZ is thought of the "hot rod" for its huge performance potential, abundance of support, and the fact that it is the last model produced without a diesel particulate filter. Information released by General Motors at the introduction of the LBZ state that the engine has an increased piston pin diameter and thicker connecting rod section over previous generations in addition to an improved block casting.

The LBZ was available mated to either the Allison 1000 six speed automatic or the ZF650 six speed manual transmission. 2007 would mark the last model year that any Duramax engine was available with a manual transmission. The Duramax LBZ was produced from 2006 to 2007 model years, with the LMM replacing it by mid-2007.

6.6L Duramax LBZ Specs


6.6L Duramax LBZ, 90 degree V8 diesel

Years Produced:

2006 - 2007

VIN Code:

D (8th digit of VIN)


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:

16.8 : 1

Minimum Cylinder Pressure:

300 psi (minimum compression test pressure)

Firing Order:


Duramax diesel cylinder numbers


4.055" (103 mm)


3.897" (99 mm)


Turbocharged and intercooled - Garrett GT3788VA variable vane turbocharger (VVT), air-to-air intercooler


Direct injection, 26,000 psi Bosch high pressure common rail with CP3 injection pump and 7 hole fuel injectors


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:

Diesel oxidation catalyst (DOC) and exhaust gas recirculation (EGR)

Peak Horsepower:

360 hp @ 3,200 rpm

Peak Torque:

650 lb-ft @ 1,600 rpm

Engine Dimensions:




Approx 30"

Approx 30"

Approx 32"

Duramax LBZ Horsepower & Torque Curve

The Duramax LBZ produced a maximum 650 lb-ft of torque at 1,600 rpm and 360 horsepower at 3,200 rpm.