The 6.6L Duramax LGH is a detuned version of the Duramax LML also introduced for the 2011 model year.It was designed specifically for chassis cab and box-delete vehicles (RPO ZW9), which are considered incomplete vehicles and therefore fall under a different Federal emissions standard category than pickups. Beginning the 2011 model year, LGH applications included the Chevrolet Silverado 2500/3500 chassis cab, GMC Sierra 2500/3500 chassis cab, Chevrolet Express 3500/4500, and GMC Savana 3500/4500. Beginning for the 2013 model year, all Sierra and Silverado chassis cab trucks received the more powerful LML instead of the LGH. The Express and Savana commercial Vans continue to use the Duramax LGH instead of the LML.

In chassis cab applications, the LGH is rated at 335 horsepower and 685 lb-ft of torque. For commercial Vans, the LGH is rated at 260 horsepower and 525 lb-ft. Both power variations retain the LML’s B20 biodiesel compatibility. In addition to a unique engine calibration, the LGH features a different turbocharger, larger EGR cooler, and higher capacity SCR system. Currently, the LGH is only available in the Chevrolet Express and GMC Savana – chassis cab trucks are only available with the LML and retain its 397 horsepower, 765 lb-ft rating. The transition from the LGH to the LML for the 2013 model year in these applications was likely a strategic move in competing with other brand commercial vehicles.


Engine: 6.6L Duramax LGH, 90 degree V8, diesel
Years Produced: 2011 – present
Applications: 2011 – current Chevrolet Express & GMC Savana

2011 – 2012 Chevrolet Silverado, GMC Sierra 2500/3500 chassis cab

VIN Code: L (8th digit of VIN)
Displacement: 403 cubic inches, 6.6 liters
Head/Block Material: Aluminum cylinder heads, cast iron engine block
Compression Ratio: 16.0 : 1
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 GT3582VA variable vane turbocharger (VVT), air-to-air intercooler
Valvetrain: OHV (overhead valve), 4 valves per cylinder
Oil Capacity: 10 quarts w/filter
Max Engine Speed: 3,450 rpm
Shift RPM: ~ 3,100 rpm
Peak Horsepower: 260 hp @ 3,100 rpm (Express/Savana Vans)

335 hp @ 3,100 rpm (Silverado/Sierra chassis cab)

Peak Torque: 525 lb-ft @ 1,600 rpm (Express/Savana Vans)

685 lb-ft @ 1,600 rpm (Silverado/Sierra chassis cab)