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 heavy-duty pickup truck geared towards 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 interior space. Introduced in 2024, this specific variant builds upon the established Sierra 3500HD platform, focusing on refinements to technology, styling, and overall refinement while maintaining its core work-truck identity.
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) DRW 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 | 8.1 kg/Hp, 123.8 Hp/tonne |
| Weight-to-torque ratio | 5.1 kg/Nm, 194.2 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 | 3239 kg (7140.77 lbs) |
| Max. weight | 6350 kg (13999.35 lbs) |
| Max load | 3111 kg (6858.58 lbs) |
| Fuel tank capacity | 136 l (35.93 US gal | 29.92 UK gal) |
| Permitted trailer load with brakes (12%) | 8323 kg (18349.07 lbs) |
| Length | 6534 mm (257.24 in) |
| Width including mirrors | 2457 mm (96.73 in) |
| Height | 2037 mm (80.2 in) |
| Wheelbase | 4127 mm (162.48 in) |
| Front track | 1731 mm (68.15 in) |
| Rear (Back) track | 1905 mm (75 in) |
| Ride height (ground clearance) | 264 mm (10.39 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, 355×40 mm |
| Rear brakes | Ventilated discs, 355×40 mm |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Cone worm with recirculation balls |
| Power steering | Hydraulic Steering |
| Tires size | 235/80 R17; 235/80 R18 |
| Wheel rims size | 6.5J x 17; 8J x 18 |
Powertrain & Engine Architecture
The heart of this Sierra 3500HD is the 6.6-liter L8T 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 employs an overhead valve (OHV) valvetrain, a traditional design known for its durability and relatively simple maintenance. The 10-speed Allison automatic transmission is a key component, designed to handle the substantial torque produced by the V8. This transmission features electronically controlled shifts for smooth and efficient operation, and is specifically tuned for heavy-duty applications. The longitudinal engine placement optimizes weight distribution for improved handling and towing stability.
Driving Characteristics
The 401 horsepower and 463.93 lb-ft of torque delivered by the 6.6L V8, coupled with the 10-speed Allison transmission, provide substantial pulling power. While not as quick as lighter-duty pickups, the Sierra 3500HD excels at tasks requiring significant torque at lower RPMs. The automatic transmission is programmed for smooth shifts during normal driving, but can quickly downshift when needed for acceleration or towing. Compared to the available Duramax diesel engine, this gasoline variant offers a different driving experience – less low-end grunt but a more responsive feel at higher speeds. The gear ratios in the Allison transmission are optimized for both towing and highway cruising, providing a balance between power and fuel efficiency.
Equipment & Trim Levels
The 2024 Sierra 3500HD Double Cab Long Bed with the 6.6L V8 typically falls into the mid-range of GMC’s heavy-duty truck offerings. Standard features generally include 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. Interior upholstery is typically cloth or vinyl, with options for leather upgrades. Higher trim levels add features like heated and ventilated seats, a premium sound system, and advanced trailering technologies. The Double Cab configuration provides ample space for passengers, while the Long Bed offers a generous cargo capacity.
Chassis & Braking
The Sierra 3500HD utilizes a robust chassis designed to withstand the stresses of heavy hauling and towing. 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, known for its durability and load-carrying capacity. Braking duties are handled by ventilated discs at all four corners, providing ample stopping power even when heavily loaded. An Anti-lock Braking System (ABS) is standard, enhancing safety and control during emergency braking situations. Hydraulic power steering provides responsive and precise steering feel.
Market Reception & Comparison
Critics generally praise the Sierra 3500HD for its robust construction, powerful engine options, and comfortable ride. The 6.6L V8 is often seen as a good option for buyers who prefer the simplicity and lower upfront cost of a gasoline engine compared to the diesel. However, fuel economy is typically lower than that of the Duramax diesel, especially when towing. Compared to competitors like the Ford Super Duty and Ram Heavy Duty, the Sierra 3500HD offers a competitive combination of features, capability, and value. The gasoline engine variant is often favored by those who don’t require the extreme towing capacity of the diesel but still need a capable heavy-duty truck.
Legacy
The GMTT1XX platform, and specifically the 6.6L V8/Allison automatic combination, is expected to offer good long-term reliability. The Allison transmission, in particular, has a strong reputation for durability. While long-term data is still emerging for the 2024 facelift, previous generations of the Sierra 3500HD have proven to be dependable work trucks. On the used car market, these trucks are likely to hold their value well, particularly those that have been well-maintained and haven’t been subjected to extreme use. The combination of power, capability, and relative simplicity makes this variant a desirable option for buyers seeking a reliable and capable heavy-duty pickup.
