6.6L Duramax L5D

The 6.6L Duramax L5D is a derivative of the L5P designed specifically for class 4/5 commercial vehicle applications. The engine is found in the 2019 and newer Chevrolet Silverado 4500HD, 5500HD, 6500HD, and International CV medium duty trucks. The Chevrolet and International medium duty platforms were developed through a strategic partnership between Navistar International and General Motors. Silverado 4500HD, 5500HD, and 6500HD truck models are essentially a Chevrolet branded International CV chassis. Likewise, the 6.6L L5D Duramax is re-branded as the International 6.6L in Navistar International CV applications. Due to the marketing similarities, there's no data that suggests there is any difference between the 6.6L turbodiesel in either GM or International applications.

6.6L L5D Duramax Engine Specs & Information

The L5D is a detuned version of the more powerful L5P offered in Chevrolet/GMC pickup and chassis cab trucks. The 6.6L Duramax L5D and International 6.6L are rated a peak 350 horsepower and 700 lb-ft of torque. The engines are mated to one of several Allison six speed automatic transmission options that include the model 1700, 1750, and 2700 series; no manual transmission is available in either the Chevrolet nor International truck platforms.

6.6L L5D Duramax, International 6.6 Diesel Specs

Engine Family:

6.6L Duramax diesel, 6.6L International diesel

RPO Code:


VIN Code:

K (8th digit of VIN)

Assembly Site:

DMAX engine plant, Moraine, Ohio

Applications/Production Years:

2019 - 2024 Chevrolet Silverado 4500HD, 5500HD, 6500HD medium duty trucks
2019 - 2024 International CV Series medium duty trucks


6.62 liters (6.6 liters nominal), 403.9 CID (403 CID nominal)


90 degree V-8

B10 Life:

Not specified

B50 Life:

Not specified


4.055 inches (103.00 mm)


3.897 inches (99.00 mm)

Bore/Stroke Ratio:

1.04 (marginally oversquare)

Compression Ratio:

16.0 : 1

Firing Order:


Cylinder Numbers:

6.6 Duramax cylinder numbers and locations

Cylinders 1, 3, 5, and 7 are located on the passenger side bank
Cylinders 2, 4, 6, and 8 are located on the driver side bank

Engine Block Material:

Cast iron

Cylinder Head Material:

Cast aluminum alloy

Injection System:

Direct injection
High pressure common rail system
Denso GS4 Gen-III solenoid fuel injectors
Denso HP4 injection pump
29,000 psi max injection pressure


Turbocharged, air-to-air intercooler
BorgWarner electronically actuated variable geometry turbocharger (VGT)


Overhead valve (OHV), standard cam-in-block, mechanical roller lifters
4 valves per cylinder (32 valve)

Cold Start Aid(s):

Traditional glow plug system, 1 per cylinder

Engine Oil Capacity:

10 quarts with oil filter change


Ultra low sulfur diesel (ULSD) or max B20 biodiesel blend

Peak Horsepower:

350 hp @ 2,700 RPM

Peak Torque:

700 lb-ft @ 1,600 RPM

Governed Speed:

2,900 rpm (electronically governed)

Emissions Equipment:

Exhaust gas recirculation (EGR), diesel oxidation catalyst (DOC), diesel particulate filter (DPF), selective catalytic reduction (SCR)

Coupled Transmissions:

Allison 1700, 1750, 2700 6 speed automatic

Engine Weight:

Approx. 835 lbs

Engine Dimensions:


Approx 30.0 inches


Approx 30.0 inches


Approx 32.0 inches

Chevy Silverado 4500HD, 5500HD, 6500HD

Chevrolet Silverado 4500HD, 5500HD, 6500HD medium duty trucks

International CV Series medium duty trucks

International CV Series Medium Duty Trucks

Allison Transmission Options

The 6.6L Duramax L5D is available coupled to one of several automatic transmissions from Allison, including 1700, 1750, and 2700 model designations in highway service (HS), rugged duty service (RDS), emergency vehicle service (EVS), and motor home series. All available transmissions feature 6 forward speeds and are applicable to different GVWR ranges; recall that the Silverado 6500HD is available with a gross vehicle weight rating of up to 23,500 lbs and a gross combined weight rating of up to 37,000 lbs.

Allison 1700/1750/2700 Transmission Ratios

Transmission Model








1700, 1750, 2700

3.10 : 1

1.80 : 1

1.40 : 1

1.00 : 1

0.70 : 1

0.61 : 1

4.49 : 1