The GMC Sierra 2500HD, in its fifth generation (GMTT1XX), received a significant facelift for the 2024 model year. This iteration continues GMC’s tradition of offering a heavy-duty pickup truck geared towards demanding tasks like towing and hauling. The Crew Cab Long Bed configuration, paired with the 6.6-liter Duramax Turbo-Diesel V8 engine and a ten-speed automatic transmission, represents a premium offering within the Sierra 2500HD lineup, positioned for buyers needing substantial capability without sacrificing comfort. Production of this specific configuration began with the 2023 model year and continues with the updated 2024 models.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD V (GMTT1XX, facelift 2024) Crew Cab Long Bed |
| Type (Engine) | 6.6 Duramax TD V8 (470 Hp) Automatic |
| Start of production | 2023 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 7.2 kg/Hp, 139.5 Hp/tonne |
| Weight-to-torque ratio | 2.5 kg/Nm, 392.4 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 | 3369 kg (7427.37 lbs.) |
| Max. weight | 4990 kg (11001.07 lbs.) |
| Max load | 1621 kg (3573.69 lbs.) |
| Fuel tank capacity | 136 l (35.93 US gal | 29.92 UK gal) |
| Permitted trailer load with brakes (12%) | 9072 kg (20000.34 lbs.) |
| Length | 6776 mm (266.77 in.) |
| Width including mirrors | 2079 mm (81.85 in.) |
| Height | 2023 mm (79.65 in.) |
| Wheelbase | 4369 mm (172.01 in.) |
| Front track | 1731 mm (68.15 in.) |
| Rear (Back) track | 1736 mm (68.35 in.) |
| Ride height (ground clearance) | 256 mm (10.08 in.) |
| Drivetrain Architecture | Rear wheel drive |
| 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 |
| 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 |
Introduction
The 2024 GMC Sierra 2500HD Crew Cab Long Bed with the 6.6L Duramax diesel and Allison automatic transmission represents a significant step up in capability for the GMC heavy-duty truck line. Built on the GMTT1XX platform, this truck is designed for owners who regularly tow large trailers, haul heavy payloads, or require a robust work truck. The facelift for 2024 brought updated styling, enhanced technology, and refinements to the already capable Duramax powertrain. This configuration slots into the higher end of the 2500HD range, offering a balance of power, comfort, and features.
Powertrain & Engine Architecture
At the heart of this Sierra 2500HD lies the L5P 6.6-liter Duramax turbocharged diesel V8 engine. This engine is a cornerstone of GMC’s heavy-duty offerings, known for its durability and substantial torque output. The engine utilizes a common-rail direct fuel injection system, delivering fuel at extremely high pressures for optimized combustion. The overhead valve (OHV) valvetrain, while a more traditional design, contributes to the engine’s robustness and low-end torque characteristics. A single variable geometry turbocharger with an intercooler further enhances performance. The engine produces 470 horsepower at 2800 rpm and a massive 975 lb-ft (1322 Nm) of torque at 1600 rpm. This torque figure is crucial for heavy towing and hauling. The Allison ten-speed automatic transmission is specifically calibrated to handle the Duramax engine’s output, providing smooth and efficient power delivery. The transmission features electronically controlled shifts and a tow/haul mode for optimized performance when towing.
Driving Characteristics
The combination of the Duramax engine and Allison transmission results in a driving experience focused on effortless power and control. While not a sports truck, the Sierra 2500HD delivers surprisingly responsive acceleration, especially considering its weight. The ten-speed automatic transmission keeps the engine in its optimal power band, providing strong pulling power at all speeds. Compared to gasoline-powered Sierra 2500HD models, the Duramax offers significantly more low-end torque, making it ideal for towing. Compared to the 6.6L gasoline engine, the diesel provides a more relaxed driving experience when towing heavy loads, requiring less frequent downshifting. The gear ratios in the Allison transmission are well-suited for both highway cruising and demanding off-road conditions. The truck’s substantial weight is noticeable, but the robust suspension and steering system provide a stable and controlled ride.
Equipment & Trim Levels
The Crew Cab Long Bed configuration typically comes standard with a generous array of features. Standard equipment often includes a user-friendly infotainment system with a touchscreen display, Apple CarPlay and Android Auto compatibility, and a suite of safety features like automatic emergency braking and lane departure warning. Interior upholstery is typically cloth or vinyl, with higher trim levels offering leather options. The dashboard layout is functional and well-organized, with easy-to-reach controls. Optional extras for this trim can include a premium audio system, heated and ventilated front seats, a power-adjustable steering column, and advanced trailering technology like a trailer tire pressure monitoring system. Trim levels like Denali add even more luxury features, such as unique exterior styling, premium leather interiors, and advanced driver-assistance systems.
Chassis & Braking
The Sierra 2500HD utilizes a robust chassis designed to withstand heavy loads and demanding conditions. The front suspension features an independent torsion bar setup with double wishbones, providing a comfortable ride and good handling. 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, with larger rotors at the rear (360x34mm) compared to the front (350x40mm). An Anti-lock Braking System (ABS) is standard. The steering system is a rack-and-pinion setup with electric power steering, providing precise and responsive steering feel. Tire sizes vary depending on the trim level and wheel size, ranging from 235/80 R17 to 265/60 R20.
Market Reception & Comparison
The GMC Sierra 2500HD with the Duramax diesel has consistently received positive reviews for its towing capability, robust powertrain, and comfortable ride. Critics often praise the engine’s impressive torque output and the Allison transmission’s smooth shifting. Fuel economy, while not a primary concern for heavy-duty truck buyers, is generally competitive within the segment. Compared to the gasoline-powered Sierra 2500HD, the Duramax diesel offers significantly better fuel economy when towing heavy loads. Compared to competitors like the Ford Super Duty and Ram 2500, the Sierra 2500HD is often seen as offering a good balance of capability, comfort, and refinement. Reliability has generally been good, although diesel engines can be more expensive to maintain than gasoline engines due to the complexity of the fuel injection system and emissions controls.
Legacy
The Duramax diesel engine has become a benchmark for reliability and longevity in the heavy-duty truck segment. The L5P version, found in the 2024 Sierra 2500HD, continues this tradition. These engines, when properly maintained, are known to exceed 200,000 miles with minimal issues. On the used car market, Sierra 2500HD models equipped with the Duramax diesel and Allison transmission command a premium price due to their proven capability and durability. The GMTT1XX platform, and specifically this powertrain combination, represents a sweet spot for buyers seeking a capable and reliable heavy-duty truck that can handle demanding tasks for years to come.
