The 6.6 liter LLY Duramax V8 engine was introduced during the 2004 model year as a replacement to the LB7 Duramax V8. As such, it powered Chevrolet Silverado Heavy-Duty and GMC Sierra Heavy-Duty pickup trucks through 2006, making up to 310 horsepower and 605 pound-feet of torque.
| Displacement: | 6.6L / 403 cu. in. |
|---|---|
| Aspiration: | Natural |
| Vehicles: | Chevrolet Silverado HD, GMC Sierra HD |
| Introduced: | mid-2004 model year |
| Discontinued: | 2006 model year |
| Predecessor: | LB7 Duramax V8 |
| Successor: | LBZ Duramax V8 |
| Assembly: | Moraine, Ohio, USA |
When the LLY Duramax V8 debuted midway through the 2004 model year, it had an SAE-certified output rating of 310 horsepower and 520 pound-feet of torque, with the latter growing by 85 to 605 pounds of twist for the 2006 model year. Variable-valve timing enabled the torque to be delviered as early as 1,600 RPM (revolutions-per-minute).
One of the biggest differences between the LLY and its predecessor, the LB7, is that the LLY is fitted with emissions controlling technology. While this had its drawbacks, due to the addition of more moving parts, meaning in more potential issues. However, the then-new technology did have its upsides, including improved drivability and a turbocharger that spooled more quickly. Not only did the improved spool time mean earlier torque delivery, it also meant less particulate pollutants.
General Motors applied what it had learned from the fuel injector woes experienced by the LB7, however, the newer engine is associated with a different issue altogether: overheating. Unsurprisingly, the issues were more severe when trucks were used for towing, with speculation ranging from restrictive air flow components to or perhaps improper maintenance of cooling components.
| Type | 6.6L V-8 Turbo-Diesel |
| GM RPO Code | LLY |
| Displacement | 403 ci |
| Valve Configuration | Overhead |
| Valves Per Cylinder | 4 |
| Assembly Site | Moraine, Ohio, USA |
| Valve Lifters | Mechanical roller |
| Firing Order | 1 – 2 – 7 – 8 – 4 – 5 – 6 – 3 |
| Bore x Stroke | 4.055 in. or 103 mm x 3.897 in. or 99 mm |
| Fuel System | Direct injection with high-pressure common rail w/ Bosch CP3 pump |
| Fuel Type | Diesel |
| Fuel Tank Size: | 26 Gallons |
| Maximum Powered Speed | 3250 rpm |
| Emissions Controls | None |
| Block | Cast iron w/ deep skirt |
| Cylinder Head | Cast aluminum |
| Intake Manifold | Cast aluminum |
| Exhaust Manifold | Cast nodular iron with steel pipe extension |
| Main Bearing Caps | Cast nodular iron |
| Crankshaft | Forged steel |
| Camshaft | Steel |
| Connecting Rods | Forged Steel |
| Engine Oil Capacity | 10 qt./9.5L w/ Filter |
| Engine Mass: | Approximately 835 pounds |
| Year | Make | Model | Transmission | Power (hp / kW) @ RPM | Torque (lb-ft / Nm) @ RPM |
|---|---|---|---|---|---|
| 2004.5-2005 | Chevrolet | Silverado HD | 5-Speed Manual or 5-Speed Allison Automatic | 310 / 232 @ 3000 | 520 / 705 @ 1600 |
| 2004.5-2005 | GMC | Sierra HD | 5-Speed Manual or 5-Speed Allison Automatic | 310 / 232 @ 3000 | 520 / 705 @ 1600 |
| 2006 | Chevrolet | Silverado HD | 5-Speed Manual or 5-Speed Allison Automatic | 310 / 232 @ 3000 | 605 / 820 @ 1800 |
| 2006 | GMC | Sierra HD | 5-Speed Manual or 5-Speed Allison Automatic | 310 / 232 @ 3000 | 605 / 820 @ 1800 |
The 6.6L Duramax LLY engine was manufactured at the GM Duramax plant in Moraine, Ohio, USA.
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