The GMC Sierra 3500HD, specifically the V (GMTT1XX) Crew Cab Long Bed configuration with the 6.6-liter V8 engine producing 401 horsepower, represents GMC’s heavy-duty pickup truck offering from the 2020 to 2023 model years. This variant occupied a significant position within the Sierra 3500HD lineup, catering to buyers needing substantial towing and payload capacity. It was positioned as a robust work truck, appealing to those in trades, agriculture, and those requiring a powerful vehicle for recreational pursuits like hauling large trailers or equipment. The “V” designation refers to the GMTT1XX platform, a significant update to GMC’s heavy-duty truck architecture.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD V (GMTT1XX) Crew Cab Long Bed |
| Type (Engine) | 6.6 V8 (401 Hp) DRW Automatic |
| Start of production | 2020 year |
| End of production | 2023 year |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 9.1 kg/Hp, 109.5 Hp/tonne |
| Weight-to-torque ratio | 5.8 kg/Nm, 171.8 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 | 3661 kg / 8071.12 lbs |
| Max. weight | 6350 kg / 13999.35 lbs |
| Max load | 2689 kg / 5928.23 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 | 2457 mm / 96.73 in |
| Height | 2033 mm / 80.04 in |
| Wheelbase | 4369 mm / 172.01 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 | The Internal combustion engine (ICE) drives the rear wheels of the vehicle. |
| Drive wheel | Rear wheel drive |
| 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 | 235/80 R17; 265/70 R17; 245/75 R17; 275/70 R18; 275/65 R20 |
| Wheel rims size | 7.5J x 17; 8J x 18; 8.5J x 20 |
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). The direct injection system contributes to improved fuel efficiency and power output. The engine produces 401 horsepower at 5200 rpm and 464 lb-ft of torque at 4000 rpm. The engine’s robust construction and relatively simple design (compared to turbocharged alternatives) prioritize durability and ease of maintenance. The engine is mated to a six-speed Hydra-Matic automatic transmission, specifically tuned for heavy-duty applications. This transmission features electronically controlled shifting and is designed to handle the high torque output of the 6.6L V8. The transmission’s gear ratios are optimized for both towing and everyday driving, providing a balance between power and fuel economy.
Driving Characteristics
The 401 hp/464 lb-ft combination in the Sierra 3500HD delivers substantial performance, particularly when it comes to towing and hauling. While not as quick as lighter-duty pickups or those equipped with more powerful engines, this configuration provides ample power for most tasks. The automatic transmission shifts smoothly and predictably, although it may occasionally hunt for the right gear when under heavy load. Compared to the available diesel engines (like the Duramax), the gasoline V8 offers a different driving experience. The diesel engines prioritize low-end torque, making them ideal for extremely heavy towing, while the gasoline engine provides a more responsive feel in everyday driving situations. The gasoline engine is also noticeably quieter than the diesel.
Equipment & Trim Levels
The Crew Cab Long Bed configuration typically came standard with a comprehensive set of features, including air conditioning, power windows and locks, a basic infotainment system with a touchscreen display, and a rearview camera. Higher trim levels, such as the SLT and Denali, added features like leather upholstery, heated and ventilated seats, a premium sound system, and advanced safety technologies. Optional extras included a sunroof, navigation system, and various towing packages. The interior design was functional and durable, with a focus on providing a comfortable and practical cabin for both work and family use.
Chassis & Braking
The Sierra 3500HD features a robust chassis designed to withstand the stresses of heavy-duty use. The front suspension utilizes a coil spring, double wishbone setup with a transverse stabilizer bar, while the rear suspension employs a rigid axle with leaf springs. This configuration provides a comfortable ride while maintaining excellent load-carrying capacity. Braking duties are handled by ventilated disc brakes on all four wheels, providing ample stopping power even when towing a heavy trailer. An Anti-lock Braking System (ABS) is standard, enhancing safety and control. The steering system is a hydraulic power steering setup, offering a responsive and precise feel.
Market Reception & Comparison
The GMC Sierra 3500HD with the 6.6L V8 and automatic transmission received generally positive reviews. Critics praised its powerful engine, comfortable ride, and spacious cabin. However, some noted that the gasoline engine’s fuel economy was lower than that of the diesel alternatives. Compared to the Duramax diesel, the gasoline V8 was often seen as a more affordable option for buyers who didn’t require the ultimate in towing capacity. The gasoline engine also appealed to those who preferred the quieter operation and simpler maintenance of a gasoline engine.
Legacy
The 6.6L L8T V8 engine and the six-speed Hydra-Matic transmission have proven to be relatively reliable powertrains. While not immune to issues, they generally require less maintenance than the more complex diesel engines. In the used car market, these Sierra 3500HD models are often sought after by buyers looking for a capable and affordable heavy-duty pickup truck. The availability of parts and service is excellent, and the engine’s robust construction ensures that it can provide many years of reliable service with proper maintenance. The GMTT1XX platform itself represented a significant step forward in terms of refinement and capability for GMC’s heavy-duty trucks, solidifying its position as a strong competitor in the segment.
