The Chevrolet Silverado 2500HD II, specifically the Extended Cab Long Box configuration equipped with the 6.6-liter Duramax Turbo Diesel V8 engine and Allison automatic transmission, represents a significant evolution in Chevrolet’s heavy-duty pickup truck lineage. Produced from 2011 to 2014, this variant occupied a desirable position within the Silverado 2500HD lineup, offering a compelling balance of towing capability, payload capacity, and refined power for demanding applications. It is based on the GMT900 platform, a refreshed version of the preceding generation, featuring updated styling and enhanced features. This particular configuration was targeted towards buyers who required substantial capability without necessarily opting for the highest, most luxurious trim levels.
Technical Specifications
| Brand | Chevrolet |
| Model | Silverado 2500 HD |
| Generation | Silverado 2500 HD II (GMT900, facelift 2011) Extended Cab Long Box |
| Type (Engine) | 6.6 Duramax TD V8 (397 Hp) Automatic |
| Start of production | 2011 |
| End of production | 2014 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 2 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 8 kg/Hp, 125.3 Hp/tonne |
| Weight-to-torque ratio | 3.1 kg/Nm, 327.3 Nm/tonne |
| Power | 397 Hp @ 3000 rpm |
| Power per litre | 60.2 Hp/l |
| Torque | 1037 Nm @ 1600 rpm (764.85 lb.-ft. @ 1600 rpm) |
| Maximum engine speed | 3000 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | Duramax LML |
| Engine displacement | 6599 cm3 (402.7 cu. in.) |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 103 mm (4.06 in.) |
| Piston Stroke | 99 mm (3.9 in.) |
| Compression ratio | 16:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Diesel Commonrail |
| Engine aspiration | Turbocharger, Intercooler |
| Valvetrain | OHV |
| Engine oil capacity | 9.5 l (10.04 US qt | 8.36 UK qt) |
| Coolant | 24 l (25.36 US qt | 21.12 UK qt) |
| Kerb Weight | 3168 kg (6984.24 lbs.) |
| Max. weight | 4536 kg (10000.17 lbs.) |
| Max load | 1368 kg (3015.92 lbs.) |
| Trunk (boot) space – maximum | 2138 l (75.5 cu. ft.) |
| Fuel tank capacity | 136 l (35.93 US gal | 29.92 UK gal) |
| Permitted trailer load with brakes (12%) | 5897 kg (13000.66 lbs.) |
| Length | 6337 mm (249.49 in.) |
| Width including mirrors | 2032 mm (80 in.) |
| Height | 1971 mm (77.6 in.) |
| Wheelbase | 4018 mm (158.19 in.) |
| Front track | 1748 mm (68.82 in.) |
| Rear (Back) track | 1709 mm (67.28 in.) |
| Ride height (ground clearance) | 216 mm (8.5 in.) |
| Minimum turning circle (turning diameter) | 15.8 m (51.84 ft.) |
| Drivetrain Architecture | Rear wheel drive |
| Number of gears and type of gearbox | 6 gears, automatic transmission Allison |
| Front suspension | Independent torsion bar, double wishbone |
| Rear suspension | Rigid axle suspension, Leaf spring |
| Front brakes | Ventilated discs, 350×40 mm |
| Rear brakes | Ventilated discs, 360×34 mm |
| Tires size | 245/75 R17; 265/70 R17; 265/70 R18; 265/60 R20 |
| Wheel rims size | 7.5J x 17; 8J x 18; 8.5J x 20 |
Powertrain & Engine Architecture
The core of this Silverado 2500HD variant is the 6.6-liter Duramax LML turbo-diesel V8 engine. This engine represents a substantial advancement in the Duramax design, incorporating a redesigned combustion chamber, an enhanced fuel injection system, and a more robust cooling system. The LML utilizes a common-rail direct injection system, delivering fuel at extremely high pressures for optimized combustion efficiency and reduced emissions. The engine also features a variable geometry turbocharger (VGT) and an intercooler to maximize power output and minimize turbo lag. The overhead valve (OHV) valvetrain, while a traditional design, is well-regarded for its durability and simplicity. Complementing this engine is the Allison 1000 six-speed automatic transmission, celebrated for its strength and reliability. This transmission is specifically engineered to manage the substantial torque output of the Duramax engine, providing smooth and confident shifting even under demanding loads. The Allison transmission incorporates a lock-up torque converter to improve fuel efficiency during highway driving.
Driving Characteristics
The 397 horsepower and 765 lb-ft of torque generated by this powertrain combination deliver impressive real-world performance. While not exhibiting the same quick acceleration as gasoline-powered trucks, the Duramax offers a broad, flat torque curve, making it exceptionally well-suited for towing and hauling. The Allison transmission’s gear ratios are optimized for both work-related tasks and comfortable highway cruising. In comparison to the 6.0L gasoline V8 option, the Duramax provides significantly greater low-end torque, simplifying the process of starting and maintaining momentum when towing heavy loads. Compared to higher-output Duramax variants, this 397 hp version provides a more balanced driving experience, prioritizing fuel economy and refinement over outright acceleration. The automatic transmission, while exceptionally robust, doesn’t offer the same degree of driver control as a manual transmission, but it simplifies operation for everyday driving and towing scenarios.
Equipment & Trim Levels
The 2011-2014 Silverado 2500HD with the Duramax/Allison combination was typically available in LT and LTZ trim levels. The LT trim included standard features such as air conditioning, power windows and locks, a basic audio system, and vinyl upholstery. The LTZ trim added features like leather upholstery, heated front seats, a premium audio system, and additional chrome exterior trim. Optional extras included a navigation system, a rear-seat entertainment system, and various towing packages. The Extended Cab configuration provided increased interior space behind the front seats, accommodating passengers or providing additional cargo room. The Long Box bed offered ample cargo capacity for transporting materials or equipment.
Chassis & Braking
The Silverado 2500HD II features a robust chassis designed to withstand the stresses associated with heavy-duty use. The front suspension utilizes an independent torsion bar setup with double wishbone control arms, providing a comfortable ride and stable handling characteristics. The rear suspension employs a traditional leaf spring design, optimized for maximizing load-carrying capacity. Braking is provided by ventilated disc brakes on all four wheels, delivering ample stopping power even when towing or hauling heavy loads. An Anti-lock Braking System (ABS) is standard equipment. Rear axle ratios varied depending on the specific configuration, influencing both towing capacity and fuel economy.
Market Reception & Comparison
The Silverado 2500HD equipped with the 6.6-liter Duramax and Allison transmission was generally well-received by both automotive critics and consumers. It was lauded for its powerful engine, smooth-shifting transmission, and impressive towing capabilities. Fuel economy, while not exceptional, was considered competitive within the heavy-duty diesel truck segment. When compared to the Ford Super Duty and Ram 2500/3500 models, the Silverado offered a compelling combination of features and value. Some critics noted that the interior design was somewhat dated compared to its competitors, but the overall build quality and reliability were consistently praised.
Legacy
The Duramax LML engine and Allison transmission pairing have proven to be exceptionally durable and reliable. These trucks continue to maintain their value in the used car market, particularly those that have been meticulously maintained. The LML Duramax is recognized for its longevity and relatively low maintenance requirements. While some early LML engines experienced issues with the exhaust gas recirculation (EGR) system, these concerns were largely addressed through software updates and improved component designs. Today, the 2011-2014 Silverado 2500HD with the 6.6-liter Duramax remains a popular choice for buyers seeking a capable and dependable heavy-duty pickup truck.
