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 work and towing applications. The Double Cab Long Bed configuration, paired with the 6.6-liter Duramax Turbo-Diesel V8 engine producing 470 horsepower, represents a potent combination aimed at buyers needing substantial capability. This specific variant sits towards the upper end of the Sierra 3500HD lineup, offering a balance of power, space, and refinement. Production began in late 2023 for the 2024 model year, building upon the established reputation of the Sierra HD series.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD V (GMTT1XX, facelift 2024) Double Cab Long Bed |
| Type (Engine) | 6.6 Duramax TD V8 (470 Hp) SRW Automatic |
| Start of production | 2024 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 7.2 kg/Hp, 138.1 Hp/tonne |
| Weight-to-torque ratio | 2.6 kg/Nm, 388.4 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 | 3404 kg (7504.54 lbs.) |
| Max. weight | 5375 kg (11849.85 lbs.) |
| Max load | 1971 kg (4345.31 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 | 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) | 284 mm (11.18 in.) |
| Drivetrain Architecture | Rear wheel drive. Internal Combustion engine (ICE) drives the rear wheels. |
| 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 |
Powertrain & Engine Architecture
The heart of this Sierra 3500HD is the 6.6-liter L5P Duramax turbo-diesel V8 engine. This engine has been a mainstay of GMC’s heavy-duty lineup for years, undergoing continuous refinement. The L5P utilizes a cast iron block and aluminum cylinder heads, providing a robust foundation for high torque output. It employs a diesel commonrail fuel injection system, delivering precise fuel metering for optimal combustion. The turbocharger, coupled with an intercooler, forces more air into the engine, boosting power and efficiency. The overhead valve (OHV) valvetrain, while a more traditional design, is known for its durability and simplicity. The engine is mated to a 10-speed Allison automatic transmission, specifically tuned for heavy-duty applications. This transmission provides smooth shifting and efficient power delivery, crucial for towing and hauling.
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 3500HD with this configuration excels at accelerating with heavy loads. The 10-speed Allison transmission is key to this, keeping the engine in its optimal power band. Compared to lower-output gasoline engine options, the Duramax offers significantly more low-end torque, making it ideal for towing large trailers or hauling substantial payloads. Compared to other Duramax variants, the 470 hp version provides a noticeable increase in power over earlier iterations, improving acceleration and overall responsiveness. The automatic transmission, while convenient, may not offer the same level of control as a manual transmission for experienced drivers in demanding situations.
Equipment & Trim Levels
The 2024 Sierra 3500HD Double Cab Long Bed with the Duramax engine typically comes well-equipped, even in base trims. Standard features generally 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 Denali, add premium features like leather upholstery, heated and ventilated seats, a premium sound system, and advanced safety technologies. Optional extras include a power sunroof, a rear-seat entertainment system, and various towing packages. The Double Cab configuration provides comfortable seating for five passengers, while the Long Bed offers ample cargo space.
Chassis & Braking
The Sierra 3500HD features a robust chassis designed to handle heavy loads. The front suspension utilizes an independent torsion bar and double wishbone setup, 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, providing ample stopping power. The front brakes measure 355×40 mm, while the rear brakes are 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
The GMC Sierra 3500HD with the 6.6-liter Duramax engine has consistently received positive reviews for its towing capacity, power, and overall capability. Critics praise the engine’s robust torque output and the smooth operation of the Allison transmission. Fuel economy, while not a primary concern for heavy-duty truck buyers, is generally considered competitive within the segment. Compared to gasoline-powered Sierra 3500HD models, the Duramax offers significantly better fuel economy when towing or hauling heavy loads. Reliability has been generally 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 L5P Duramax engine has established itself as a reliable and powerful workhorse in the heavy-duty truck market. The combination of the Duramax engine and Allison transmission has proven to be durable and long-lasting, with many examples exceeding 200,000 miles with proper maintenance. In the used car market, Sierra 3500HD models equipped with this powertrain command a premium price due to their reputation for capability and longevity. The 2024 facelifted model builds upon this legacy, offering updated styling, improved technology, and continued performance.
