The GMC Sierra 3500HD, specifically the V (GMTT1XX) Regular Cab Long Bed configuration with the 6.6-liter V8 engine producing 401 horsepower, was a heavy-duty pickup truck manufactured by General Motors from 2020 to 2023. This variant occupied a significant position within the Sierra 3500HD lineup, catering to buyers needing substantial towing and payload capacity. It represented GMC’s offering in the competitive heavy-duty truck segment, directly competing with Ford’s F-350 and Ram’s 3500 models. The “V” designation refers to the GMTT1XX platform, a significant update to the previous GMT900 series, bringing improvements in technology, capability, and refinement.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD V (GMTT1XX) Regular Cab Long Bed |
| Type (Engine) | 6.6 V8 (401 Hp) 4WD DRW Automatic |
| Start of production | 2020 |
| End of production | 2023 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 2 |
| Doors | 2 |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 7.7 kg/Hp, 129.7 Hp/tonne |
| Weight-to-torque ratio | 4.9 kg/Nm, 203.4 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, VVT |
| 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 | 3092 kg (6816.69 lbs) |
| Max. weight | 6350 kg (13999.35 lbs) |
| Max load | 3258 kg (7182.66 lbs) |
| Fuel tank capacity | 136 l (35.93 US gal | 29.92 UK gal) |
| Permitted trailer load with brakes (12%) | 7620 kg (16799.22 lbs) |
| Length | 5982 mm (235.51 in) |
| Width including mirrors | 2457 mm (96.73 in) |
| Height | 2038 mm (80.24 in) |
| Wheelbase | 3595 mm (141.54 in) |
| Front track | 1731 mm (68.15 in) |
| Rear (Back) track | 1905 mm (75 in) |
| Ride height (ground clearance) | 266 mm (10.47 in) |
| Drivetrain Architecture | The Internal combustion engine (ICE) drives the rear wheels permanently, and the front wheels are driven through an electrically or mechanically operated clutch if necessary. |
| Drive wheel | All wheel drive (4×4) |
| Number of gears and type of gearbox | 6 gears, automatic transmission Hydra-Matic |
| Front suspension | Coil spring, Double wishbone, Transverse stabilizer |
| 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 | 265/70 R17; 245/75 R17; 275/70 R18 |
| Wheel rims size | 7.5J x 17; 8J x 18 |
Powertrain & Engine Architecture
At the heart of this Sierra 3500HD variant lies the 6.6-liter L8T V8 gasoline engine. This engine is a naturally aspirated, overhead valve (OHV) design featuring variable valve timing (VVT). Direct fuel injection is employed to optimize combustion efficiency and power output. The engine produces 401 horsepower at 5200 rpm and 464 lb-ft of torque at 4000 rpm. The Hydra-Matic 6-speed automatic transmission is the sole transmission option for this configuration. This transmission is known for its durability and ability to handle the high torque output of the 6.6L V8. The transmission features electronically controlled shifting and tow/haul mode for optimized performance when towing heavy loads. The engine’s longitudinal mounting and rear-wheel-drive bias, coupled with a selectable four-wheel-drive system, provide robust traction and capability.
Driving Characteristics
The 6.6L V8 and 6-speed automatic combination delivers a balance of power and usability. While not as quick as some of the diesel-powered Sierra 3500HD models, the gasoline engine provides ample power for everyday driving and towing. The automatic transmission shifts smoothly and predictably, and the tow/haul mode effectively manages gear selection when hauling heavy loads. The gear ratios are optimized for towing, providing strong low-end torque. Compared to the diesel variants, this gasoline engine is noticeably quieter and smoother, but it sacrifices fuel economy and ultimate towing capacity. The dual rear wheel (DRW) configuration enhances stability when towing and increases payload capacity.
Equipment & Trim Levels
The Regular Cab Long Bed 3500HD with the 6.6L V8 typically came standard with features like air conditioning, power windows and locks, a basic infotainment system with a touchscreen display, and a rearview camera. Higher trim levels, such as the SLE and Denali, added features like leather upholstery, heated and ventilated seats, a premium sound system, and advanced safety technologies. Optional extras included a gooseneck hitch, a fifth-wheel hitch, and various bed accessories. The interior, while functional, prioritized durability over luxury in the base trims. The long bed configuration provided ample cargo space for hauling materials and equipment.
Chassis & Braking
The Sierra 3500HD features a robust chassis designed to withstand heavy loads. The front suspension utilizes coil springs and a double wishbone design with a transverse stabilizer bar, while the rear suspension employs a traditional leaf spring setup. This configuration provides a comfortable ride while maintaining excellent load-carrying capacity. Ventilated disc brakes are used on all four wheels, providing ample stopping power. The anti-lock braking system (ABS) enhances safety by preventing wheel lockup during hard braking. The DRW configuration contributes to increased stability and braking performance.
Market Reception & Comparison
Critics generally praised the Sierra 3500HD’s overall capability and refinement. The 6.6L V8 engine was considered a good option for buyers who preferred the simplicity and lower upfront cost of a gasoline engine compared to the more expensive diesel alternatives. However, fuel economy was a common criticism, as the gasoline engine consumed significantly more fuel than the diesel options, especially when towing. Compared to the 6.6L Duramax diesel, the gasoline engine offered less towing capacity and lower torque. The gasoline engine was often favored by those who did not require the maximum towing capacity and preferred a quieter, smoother driving experience.
Legacy
The GMTT1XX Sierra 3500HD with the 6.6L V8 and 6-speed automatic has proven to be a relatively reliable powertrain. The L8T engine is known for its durability, and the Hydra-Matic transmission is capable of handling high torque loads. In the used car market, these trucks are often sought after by buyers looking for a capable and affordable heavy-duty pickup. Maintenance costs are generally lower for the gasoline engine compared to the diesel, making it an attractive option for budget-conscious buyers. While not as popular as the diesel variants, the 6.6L V8-powered Sierra 3500HD remains a viable option for those needing a powerful and reliable work truck.
