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 | L5D | |
| 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 |
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| Displacement | 6.62 liters (6.6 liters nominal), 403.9 CID (403 CID nominal) | |
| Configuration | 90 degree V-8 | |
| B10 Life | Not specified | |
| B50 Life | Not specified | |
| Bore | 4.055 inches (103.00 mm) | |
| Stroke | 3.897 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 |
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| 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 |
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| Aspiration | Turbocharged, air-to-air intercooler BorgWarner electronically actuated variable geometry turbocharger (VGT) |
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| Valvetrain | Overhead valve (OHV), standard cam-in-block, mechanical roller lifters 4 valves per cylinder (32 valve) |
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| Cold Start Aid(s) | Traditional glow plug system, 1 per cylinder | |
| Engine Oil Capacity | 10 quarts with oil filter change | |
| Fuel | Ultra low sulfur diesel (ULSD) or max B20 biodiesel blend | |
| Horsepower | 350 hp @ 2,700 rpm | |
| 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 | Length | Approx 30.0 inches |
| Width | Approx 30.0 inches | |
| Height | Approx 32.0 inches | |
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 | 1st | 2nd | 3rd | 4th | 5th | 6th | Reverse |
| 1700, 1750, 2700 | 3.10 : 1 | 1.80 : 1 | 1.40 : 1 | 1.00 : 1 | 0.70 : 1 | 0.61 : 1 | 4.49 : 1 |