The GMC Sierra 3500HD, in its fifth generation (GMTT1XX), received a significant facelift for the 2024 model year. This iteration continues GMC’s tradition of offering a robust and capable heavy-duty pickup truck aimed at demanding tasks like towing and hauling. The Double Cab Long Bed configuration, paired with the 6.6-liter V8 gasoline engine producing 401 horsepower, represents a popular choice for buyers needing a balance of capability and everyday usability. This specific variant occupies a middle ground in the Sierra 3500HD lineup, offering more power and towing capacity than the base engine options, but remaining more accessible than the top-tier Duramax diesel models.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD V (GMTT1XX, facelift 2024) Double Cab Long Bed |
| Type (Engine) | 6.6 V8 (401 Hp) SRW Automatic |
| Start of production | 2024 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 7.7 kg/Hp, 130.1 Hp/tonne |
| Weight-to-torque ratio | 4.9 kg/Nm, 204 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 | 3083 kg (6796.85 lbs) |
| Max. weight | 5125 kg (11298.69 lbs) |
| Max load | 2042 kg (4501.84 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 | 6534 mm (257.24 in) |
| Width including mirrors | 2079 mm (81.85 in) |
| Height | 2054 mm (80.87 in) |
| Wheelbase | 4127 mm (162.48 in) |
| Front track | 1731 mm (68.15 in) |
| Rear (Back) track | 1736 mm (68.35 in) |
| Ride height (ground clearance) | 257 mm (10.12 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 | 275/70 R18; 275/65 R20 |
| Wheel rims size | 8J x 18; 8.5J x 20 |
Introduction
The 2024 GMC Sierra 3500HD Double Cab Long Bed with the 6.6L V8 and automatic transmission represents GMC’s commitment to providing a heavy-duty truck capable of handling significant workloads. Built on the GMTT1XX platform, this facelifted model builds upon the strengths of its predecessor, offering improved technology and refinement. The Double Cab configuration provides a useful blend of passenger space and cargo bed length, making it suitable for both work and family needs. This particular variant is positioned as a strong contender for buyers who require substantial towing and hauling capacity without opting for the higher cost and complexity of a diesel engine.
Powertrain & Engine Architecture
At the heart of this Sierra 3500HD lies the L8T 6.6-liter naturally aspirated V8 gasoline engine. This engine utilizes direct fuel injection, a technology that improves efficiency and power output by injecting fuel directly into the combustion chamber. The engine features an overhead valve (OHV) valvetrain, a design known for its simplicity and durability. The 10-speed Allison automatic transmission is a key component of this powertrain. This transmission offers a wide range of gear ratios, optimizing engine performance for both towing and fuel economy. The Allison transmission is renowned for its robustness and smooth shifting characteristics. The engine produces 401 horsepower at 5200 rpm and 629 Nm (463.93 lb-ft) of torque at 4000 rpm, providing ample power for demanding tasks.
Driving Characteristics
The 6.6L V8 and 10-speed Allison combination delivers a noticeable amount of power, making the Sierra 3500HD capable of accelerating briskly when unladen. However, its true strength lies in its ability to tow and haul heavy loads. The 10-speed transmission allows the engine to stay within its optimal power band, even when carrying a significant payload or towing a large trailer. Compared to the higher-output diesel variants, this gasoline engine offers a more traditional driving experience with a more readily accessible power curve. While the diesel engines excel in low-end torque, the V8 provides a more linear power delivery. The automatic transmission shifts smoothly and efficiently, contributing to a comfortable driving experience, even during demanding tasks.
Equipment & Trim Levels
The 2024 Sierra 3500HD Double Cab Long Bed 6.6L V8 typically comes standard with a comprehensive suite of features. These 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 Denali, add premium features like leather upholstery, heated and ventilated seats, a premium sound system, and advanced safety technologies. Optional extras for this variant often include a trailer brake controller, a bed liner, and various appearance packages.
Chassis & Braking
The Sierra 3500HD features a robust chassis designed to withstand the stresses of heavy-duty use. The front suspension utilizes an independent torsion bar and double wishbone setup, providing a comfortable ride and good handling characteristics. The rear suspension employs a traditional rigid axle with leaf springs, 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, enhancing safety during emergency braking situations. The steering system utilizes a cone worm with recirculation balls, providing precise and responsive steering feel.
Market Reception & Comparison
Critics generally praised the 2024 Sierra 3500HD for its capable powertrain, comfortable ride, and well-appointed interior. The 6.6L V8 engine was noted for its ample power and smooth operation. Compared to the diesel variants, the gasoline engine offers a lower initial cost and potentially lower maintenance expenses. However, it typically delivers lower fuel economy and less low-end torque. Against competitors like the Ford Super Duty and Ram 3500, the Sierra 3500HD holds its own, offering a compelling combination of capability, comfort, and value.
Legacy
The 6.6L V8 engine has a long-standing reputation for reliability and durability in GMC and Chevrolet trucks. While the Allison 10-speed automatic transmission is a relatively newer addition, it has quickly gained a reputation for its smooth operation and robust construction. In the used car market, Sierra 3500HD models equipped with this powertrain are generally well-regarded, offering a good balance of capability and affordability. Regular maintenance, including oil changes and transmission fluid services, is crucial for ensuring the long-term reliability of this powertrain.
