The GMC Sierra 3500HD V (GMTT1XX) Crew Cab Long Bed, equipped with the 6.6-liter V8 engine producing 401 horsepower and paired with a 4WD SRW automatic transmission, represents a significant offering in the heavy-duty pickup truck segment. Produced from 2020 to 2023, this variant occupied a prominent position within the broader Sierra 3500HD lineup, catering to buyers requiring substantial towing and hauling capabilities combined with a degree of comfort and refinement. It builds upon the foundation of the GMTT1XX platform, a robust chassis designed for demanding workloads.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD V (GMTT1XX) Crew Cab Long Bed |
| Type (Engine) | 6.6 V8 (401 Hp) 4WD SRW Automatic |
| Start of production | 2020 |
| End of production | 2023 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 9.2 kg/Hp, 108.7 Hp/tonne |
| Weight-to-torque ratio | 5.9 kg/Nm, 170.5 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 | 3690 kg (8135.06 lbs) |
| Max. weight | 5557 kg (12251.09 lbs) |
| Max load | 1867 kg (4116.03 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 | 6759 mm (266.1 in) |
| Width including mirrors | 2079 mm (81.85 in) |
| Height | 2049 mm (80.67 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) | 283 mm (11.14 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, 360×34 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 |
Introduction
The GMC Sierra 3500HD V (GMTT1XX) Crew Cab Long Bed with the 6.6L V8 and 4WD automatic transmission, launched in 2020 and continuing through 2023, is a heavy-duty pickup truck designed for demanding tasks. It represents the fifth generation of the Sierra 3500HD, built on the GMTT1XX platform, which prioritizes strength and durability. This configuration aimed to provide a balance between powerful performance, comfortable interior space with the Crew Cab layout, and the versatility of a long bed. It was positioned as a workhorse for owners needing to tow large trailers, haul heavy loads, and navigate challenging terrain.
Powertrain & Engine Architecture
At the heart of this Sierra 3500HD lies the L8T 6.6-liter naturally aspirated V8 engine. This engine utilizes direct fuel injection, a technology that improves fuel efficiency and power output by injecting fuel directly into the combustion chamber. The engine also features an Overhead Valve (OHV) valvetrain with Variable Valve Timing (VVT), optimizing engine performance across a wider range of engine speeds. The engine produces 401 horsepower at 5200 rpm and 629 lb-ft of torque at 4000 rpm. This torque figure is crucial for heavy towing and hauling. The engine is longitudinally mounted in the chassis. The powertrain is coupled with a six-speed Hydra-Matic automatic transmission, known for its durability and smooth shifting. This transmission is electronically controlled, adapting shift points based on driving conditions and load.
Driving Characteristics
The 6.6L V8 and six-speed automatic combination delivers a robust driving experience. While not as quick as some lighter-duty pickups, the Sierra 3500HD excels in providing consistent, usable power for demanding tasks. The automatic transmission is tuned for towing, with lower gear ratios designed to maximize pulling power. Compared to potential diesel variants, this gasoline engine offers a more responsive feel at lower RPMs, but sacrifices the ultimate low-end torque and fuel economy of a diesel. The 4WD system provides enhanced traction in off-road conditions and inclement weather. The long bed configuration, while reducing maneuverability in tight spaces, provides ample cargo capacity.
Equipment & Trim Levels
The Sierra 3500HD Crew Cab Long Bed offered a range of trim levels, with the specific standard equipment varying accordingly. Generally, this configuration included features such as air conditioning, power windows and locks, a basic infotainment system with a touchscreen display, and a rearview camera. Higher trim levels added features like leather upholstery, heated and ventilated front seats, a premium sound system, and advanced safety technologies. Optional extras included a sunroof, navigation system, and various towing packages. The Crew Cab configuration provides generous passenger space, making it suitable for both work and family use.
Chassis & Braking
The GMTT1XX platform features a fully boxed frame constructed from high-strength steel, providing a solid foundation for heavy-duty use. The front suspension utilizes a coil spring, double wishbone design with a transverse stabilizer bar, enhancing ride comfort and handling. The rear suspension employs a traditional leaf spring setup, 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, improving braking performance and stability. The steering system is a cone worm with recirculation balls, providing a direct and responsive feel.
Market Reception & Comparison
The GMC Sierra 3500HD V (GMTT1XX) Crew Cab Long Bed with the 6.6L V8 received generally positive reviews, particularly from buyers prioritizing gasoline engine simplicity and responsiveness. Critics noted its strong towing capacity and comfortable ride quality. Compared to the diesel-powered Sierra 3500HD models, the gasoline variant offered a lower initial purchase price but suffered from lower fuel economy and reduced low-end torque. Against competitors like the Ford Super Duty and Ram 3500, the Sierra 3500HD held its own, offering a compelling combination of features and performance.
Legacy
The L8T 6.6L V8 engine, when paired with the six-speed automatic transmission, has proven to be a relatively reliable powertrain. While not without its potential issues (such as occasional active fuel management system problems), it generally offers good longevity with proper maintenance. In the used car market, these Sierra 3500HD models remain popular choices for buyers seeking a capable and dependable heavy-duty pickup truck. Their gasoline engines are often seen as less complex and potentially less expensive to repair than their diesel counterparts, making them an attractive option for those prioritizing long-term ownership costs.
