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.
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 were rated a peak 350 horsepower and 700 lb-ft of torque through the 2023 model year, but got a 50 lb-ft increase for 2024. 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.
Engine Specs
| Name | 6.6L Duramax, 6.6L International | |
|---|---|---|
| RPO Code | L5D | |
| Vin Code | K (8th digit of VIN) | |
| Engine Family | Duramax 6600 | |
| Assembly Plant(s) | DMAX engine plant, Moraine, Ohio | |
| Type | 4 cycle diesel, turbocharged, liquid cooled | |
| Configuration | 90° V8 | |
| Applications | 2019 - 2026 Chevrolet Silverado 4500HD, 5500HD, 6500HD medium duty trucks 2019 - 2026 International CV Series medium duty trucks |
|
| Displacement (nominal) | 6.6 liters, 403 cubic inches | |
| Displacement (actual) | 6.595 liters, 402.49 cubic inches | |
| Bore | 4.0551 inches (103.00 mm) | |
| Stroke | 3.8976 inches (99.00 mm) | |
| Bore/Stroke Ratio | 1.04 (marginally oversquare) | |
| Compression Ratio | 16.0:1 | |
| Firing Order | 1-2-7-8-4-5-6-3 | |
| Cylinder Numbers | 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 See cylinder numbers in figure 1 (below) |
|
| Engine Block Material | Cast iron with induction hardened cylinder walls | |
| Cylinder Head Material | Cast aluminum alloy | |
| Injection System | Direct injection, high pressure common rail | |
| Fuel Injectors | Denso GS4 Gen-III solenoid fuel injectors - up to 7 injection events per combustion sequence | |
| Injection Pump | Denso HP4 injection pump | |
| Injection Pressure | 29,000 psi max | |
| Aspiration | Turbocharged & intercooled, air-to-air charge air cooler | |
| Turbocharger | BorgWarner B2BV-70A variable geometry turbocharger, electronically actuated, non-wastegated | |
| Reciprocating Assembly | Cast aluminum alloy full floating pistons with "re-melt" piston bowl rim Cast nodular iron main bearing caps Forged steel crankshaft Steel camshaft Powdered metal iron connecting rods |
|
| Valvetrain | Overhead valve (OHV), standard cam-in-block, mechanical roller lifters 4 valves per cylinder (32 valve) |
|
| Intake Valve Diameter | 1.30 inches (33.0 mm) | |
| Exhaust Valve Diameter | 1.22 inches (31.0 mm) | |
| Cold Start Aids | Ceramic glow plugs, 1 per cylinder | |
| Engine Oil Capacity | 10 quarts with oil filter change | |
| Engine Oil Spec | See viscosity chart at 6.6L Duramax service guide | |
| Oil Pump Type | Gear type driven off crankshaft | |
| Lube Oil Filter | 2017 - 2019 | ACDelco PF2232 (standard) ACDelco UPF2232R (Gold) |
| 2020 - 2026 | ACDelco PF63 | |
| Fuel | Ultra low sulfur diesel (ULSD) or max B20 biodiesel blend | |
| Power | 2019 - 2023 | 350 hp @ 2,700 rpm |
| 2024 - 2026 | 350 hp @ 2,500 rpm | |
| Torque | 2019 - 2023 | 700 lb-ft @ 1,600 rpm |
| 2024 - 2026 | 750 lb-ft @ 1,400 rpm | |
| Idle Speed | 680 rpm [1] | |
| Max Governed Speed | 2,900 rpm (electronically governed) | |
| B10 Life | Not specified | |
| B50 Life | ||
| Emissions Equipment | Selective catalytic reduction (SCR, requires diesel exhaust fluid), diesel particulate filter (DPF), diesel oxidation catalyst (DOC), cooled exhaust gas recirculation (EGR) w/ intake throttle | |
| Engine Weight | Approx. 835 lbs | |
| Engine Dimensions | Length | 31.8 inches |
| Width | 35.4 inches | |
| Height | 39.1 inches | |
| Coupled Transmissions | Allison 1700, 1750, 2700 6 speed automatic | |
[1] - Engine idle speed is electronically controlled and will vary with conditions that include regeneration status, engine temperature, and electrical demand; idle speed may be as low as 600 rpm
Coupled Transmissions
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.
Ratios
| Gear | Ratio (:1) |
|---|---|
| 1st | 3.10 |
| 2nd | 1.80 |
| 3rd | 1.40 |
| 4th | 1.00 |
| 5th | 0.70 |
| 6th | 0.61 |
| Reverse | 4.49 |
Editor, Diesel Hub