The GMC Sierra 2500HD, in its fifth generation (GMTT1XX), received a significant facelift for the 2024 model year. This article focuses specifically on the Crew Cab Long Bed configuration equipped with the 6.6-liter V8 gasoline engine producing 401 horsepower, paired with a 10-speed automatic transmission. Introduced in 2023 with the facelift, this variant represents a balance between capability and refinement within the Sierra 2500HD lineup, targeting buyers needing substantial towing and hauling capacity without opting for the diesel engine’s higher price point.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD V (GMTT1XX, facelift 2024) Crew Cab Long Bed |
| Type (Engine) | 6.6 V8 (401 Hp) Automatic |
| Start of production | 2023 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 7.6 kg/Hp, 131.2 Hp/tonne |
| Weight-to-torque ratio | 4.9 kg/Nm, 205.8 Nm/tonne |
| Power | 401 Hp @ 5200 rpm |
| Torque | 629 Nm @ 4000 rpm, 463.93 lb.-ft. @ 4000 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | L8T |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 103.25 mm (4.06 in) |
| Piston Stroke | 98 mm (3.86 in) |
| Compression ratio | 10.8:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Direct injection |
| Engine aspiration | Naturally aspirated engine |
| Valvetrain | OHV |
| Engine oil capacity | 7.6 l (8.03 US qt | 6.69 UK qt) |
| Coolant | 14.6 l (15.43 US qt | 12.85 UK qt) |
| Kerb Weight | 3056 kg (6737.33 lbs) |
| Max. weight | 4672 kg (10300 lbs) |
| Max load | 1616 kg (3562.67 lbs) |
| Fuel tank capacity | 136 l (35.93 US gal | 29.92 UK gal) |
| Permitted trailer load with brakes (12%) | 7257 kg (15998.95 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 | The Internal combustion engine (ICE) drives the rear wheels of the vehicle. |
| Drive wheel | 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, 355×40 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 | 245/75 R17; 265/70 R17; 275/70 R18; 275/65 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 V8 and 10-speed automatic represents GMC’s offering for customers needing a heavy-duty pickup truck with gasoline power. Positioned within the Sierra 2500HD range, this configuration slots below the more expensive and torque-rich Duramax diesel variants, and above the standard work truck trims. The GMTT1XX platform, underpinning this generation, prioritizes increased rigidity and improved interior refinement compared to its predecessor. The facelift for 2024 brought updated styling, enhanced technology, and a revised interior, aiming to elevate the Sierra 2500HD’s appeal in a competitive segment.
Powertrain & Engine Architecture
At the heart of this Sierra 2500HD is the L8T 6.6-liter naturally aspirated V8 engine. This engine utilizes direct fuel injection, a feature that improves efficiency and power output compared to traditional port fuel injection systems. The engine employs an overhead valve (OHV) valvetrain, a design choice often favored in heavy-duty applications for its simplicity and durability. The 10-speed Allison automatic transmission is a key component, providing a wide gear ratio spread for optimized towing and hauling performance. This transmission allows the engine to operate within its optimal power band more frequently, improving both efficiency and responsiveness. The Allison transmission is known for its robustness and ability to handle high torque loads.
Driving Characteristics
The 401 horsepower and 464 lb-ft of torque delivered by the 6.6L V8, coupled with the 10-speed automatic, provide adequate power for most heavy-duty tasks. While not as effortlessly powerful as the Duramax diesel, this gasoline engine offers a more familiar driving experience for those accustomed to traditional V8 power delivery. The 10-speed transmission helps mitigate the engine’s limitations, providing quick downshifts for passing maneuvers and maintaining optimal engine speed when towing. However, the gasoline engine requires higher RPMs to produce peak power compared to the diesel, which can result in a slightly more noticeable engine sound under heavy load. The wide gear ratios of the Allison transmission contribute to a relatively smooth and refined driving experience, even when unladen.
Equipment & Trim Levels
The Crew Cab Long Bed configuration, even in its base trims, offers a generous level of standard equipment. Features typically include air conditioning, power windows and locks, a touchscreen infotainment system with Apple CarPlay and Android Auto compatibility, and a rearview camera. Higher trim levels, such as the SLT and Denali, add features like leather upholstery, heated and ventilated front seats, a premium sound system, and advanced safety technologies like adaptive cruise control and lane departure warning. Optional extras for this variant often include a power sunroof, a spray-in bedliner, and various towing packages.
Chassis & Braking
The Sierra 2500HD utilizes a fully boxed frame for enhanced rigidity and durability. The front suspension consists of an independent torsion bar setup with double wishbones, providing a comfortable ride even when carrying heavy loads. 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 front (355×40 mm) compared to the rear (360×34 mm). An Anti-lock Braking System (ABS) is standard. Steering is accomplished via a hydraulic power steering system with a cone worm and recirculation balls mechanism.
Market Reception & Comparison
Critics generally praised the 2024 Sierra 2500HD for its improved interior and updated technology. The 6.6L V8/10-speed automatic combination received mixed reviews. While acknowledged as capable, it was often seen as less refined and less fuel-efficient than the Duramax diesel option. Compared to the diesel, the gasoline engine offers a lower initial purchase price but higher long-term operating costs due to fuel consumption. Against competitors like the Ford Super Duty and Ram 2500, the Sierra 2500HD with the 6.6L V8 holds its own in terms of capability, but the diesel-powered rivals often offer superior towing capacity and fuel economy.
Legacy
The L8T 6.6L V8 engine, while not as widely celebrated as the Duramax diesel, has proven to be a reliable and durable powerplant. The Allison 10-speed automatic transmission further enhances the powertrain’s longevity. In the used car market, Sierra 2500HD models equipped with this powertrain combination represent a good value for buyers seeking a capable heavy-duty truck without the premium price tag of a diesel. Regular maintenance, including oil changes and transmission fluid services, is crucial for ensuring the long-term reliability of this powertrain. As with any heavy-duty truck, careful attention to towing capacity and load limits is essential for preventing premature wear and tear.
