The GMC Sierra 2500HD V, specifically the 2024 facelift model with the 6.6L Duramax Turbo Diesel V8 engine paired with a 10-speed automatic transmission and four-wheel drive, represents GMC’s heavy-duty pickup truck offering. Introduced for the 2023 model year as part of the GMTT1XX generation, this configuration caters to buyers needing substantial towing and hauling capacity. This particular variant occupies a premium position within the 2500HD lineup, offering a balance of power, refinement, and capability. It’s designed for demanding tasks, from commercial applications to recreational towing of large trailers and boats.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD V (GMTT1XX, facelift 2024) Regular Cab Long Bed |
| Type (Engine) | 6.6 Duramax TD V8 (470 Hp) 4WD Automatic |
| Start of production | 2023 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 2 |
| Doors | 2 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 6.8 kg/Hp, 147.8 Hp/tonne |
| Weight-to-torque ratio | 2.4 kg/Nm, 415.7 Nm/tonne |
| Power | 470 Hp @ 2800 rpm |
| Power per litre | 71.2 Hp/l |
| Torque | 1322 Nm @ 1600 rpm (975.06 lb.-ft. @ 1600 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | L5P |
| Engine displacement | 6604 cm3 (403 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 | 28.5 l (30.12 US qt | 25.08 UK qt) |
| Kerb Weight | 3180 kg (7010.7 lbs.) |
| Max. weight | 4944 kg (10899.65 lbs.) |
| Max load | 1764 kg (3888.95 lbs.) |
| Fuel tank capacity | 106 l (28 US gal | 23.32 UK gal) |
| Permitted trailer load with brakes (12%) | 6577 kg (14499.8 lbs.) |
| Length | 6002 mm (236.3 in.) |
| Width including mirrors | 2076 mm (81.73 in.) |
| Height | 2030 mm (79.92 in.) |
| Wheelbase | 3595 mm (141.54 in.) |
| Front track | 1731 mm (68.15 in.) |
| Rear (Back) track | 1736 mm (68.35 in.) |
| Ride height (ground clearance) | 259 mm (10.2 in.) |
| Drivetrain Architecture | All wheel drive (4×4). ICE drives rear wheels, front wheels engaged via clutch. |
| Number of gears and type of gearbox | 10 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 |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Cone worm with recirculation balls |
| Power steering | Hydraulic Steering |
| Tires size | 235/80 R17; 265/70 R17; 245/75 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 heart of this Sierra 2500HD is the 6.6-liter L5P Duramax turbocharged diesel V8 engine. This engine is a cornerstone of GMC’s heavy-duty lineup, known for its robust construction and substantial torque output. The L5P utilizes a cast iron block, aluminum cylinder heads, and a robust rotating assembly designed for longevity. It employs a diesel commonrail fuel injection system, delivering highly pressurized fuel directly into the cylinders for efficient combustion. The turbocharger, coupled with an intercooler, forces more air into the engine, boosting power and torque. The engine features an overhead valve (OHV) valvetrain, a design choice prioritizing durability and low-end torque over high-revving performance. The 10-speed Allison automatic transmission is specifically calibrated to handle the engine’s immense torque, providing smooth and efficient power delivery. This transmission features electronically controlled shifts and multiple driving modes, including tow/haul mode, optimizing performance for heavy loads.
Driving Characteristics
The 470 horsepower and 1322 lb-ft of torque delivered by this powertrain translate into impressive real-world performance. While not designed for outright speed, the Sierra 2500HD excels at accelerating with heavy loads. The 10-speed Allison transmission keeps the engine in its optimal power band, providing strong acceleration even when towing. Compared to lower-output gasoline engine options, the Duramax diesel offers significantly more torque at lower RPMs, making it ideal for hauling and towing. The automatic transmission, while smooth, may not offer the same level of driver engagement as a manual transmission. However, the tow/haul mode effectively manages gear selection to prevent excessive shifting and maximize engine braking on descents.
Equipment & Trim Levels
The 2500HD Regular Cab Long Bed with the Duramax engine typically comes standard with a robust set of features. These include air conditioning, power windows and locks, a basic infotainment system with a touchscreen display, and a rearview camera. Higher trim levels, such as Denali, add premium features like leather upholstery, heated and ventilated seats, a premium sound system, and advanced safety technologies. Optional extras for this variant include a gooseneck hitch, bed liner, upgraded wheels, and various driver-assistance systems.
Chassis & Braking
The Sierra 2500HD features a heavy-duty chassis designed to withstand the stresses of heavy hauling. The front suspension utilizes an independent torsion bar setup with double wishbones, providing a comfortable ride while maintaining stability. The rear suspension employs a traditional leaf spring design, optimized for load-carrying capacity. Braking duties are handled by ventilated disc brakes on all four wheels, providing ample stopping power. An Anti-lock Braking System (ABS) is standard. Due to the vehicle’s weight, the rear brakes are slightly larger (360x34mm) than the front brakes (350x40mm). Hydraulic power steering provides responsive and precise steering control.
Market Reception & Comparison
The Duramax diesel engine has consistently received positive reviews for its power, reliability, and fuel efficiency. Critics generally praise the Sierra 2500HD’s towing and hauling capabilities, as well as its comfortable ride quality. Compared to gasoline-powered 2500HD models, the Duramax diesel offers superior fuel economy when towing heavy loads. However, the diesel engine carries a higher initial cost and may require more expensive maintenance. Compared to competitors like the Ford Super Duty and Ram 2500, the Sierra 2500HD is often seen as a well-rounded offering, balancing capability, comfort, and technology.
Legacy
The L5P Duramax engine has proven to be a remarkably durable and reliable powertrain. With proper maintenance, these engines can easily exceed 200,000 miles. On the used car market, Sierra 2500HD models equipped with the Duramax diesel engine command a premium price due to their reputation for longevity and capability. The GMTT1XX generation, including the 2024 facelift, represents a refinement of the Duramax platform, addressing some earlier concerns regarding emissions systems and improving overall reliability. This combination of power, durability, and capability ensures the 2024 GMC Sierra 2500HD with the 6.6L Duramax will remain a sought-after workhorse for years to come.
