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 mainstay of GMC’s heavy-duty truck lineup from the 2020 to 2023 model years. This variant represented a robust, work-oriented offering within the Sierra 3500HD range, positioned as a capable solution for demanding towing and hauling tasks. It catered to buyers needing serious capability in a traditional, no-frills package. The GMTT1XX platform, introduced in 2020, brought significant updates to the Sierra HD line, focusing on increased strength, improved technology, and enhanced interior refinement compared to its predecessor.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD V (GMTT1XX) Regular 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 | 2 |
| Doors | 2 |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 7 kg/Hp, 141.9 Hp/tonne |
| Weight-to-torque ratio | 4.5 kg/Nm, 222.6 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 | 2826 kg (6230.26 lbs) |
| Max. weight | 4876 kg (10749.74 lbs) |
| Max load | 2050 kg (4519.48 lbs) |
| Fuel tank capacity | 136 l (35.93 US gal | 29.92 UK gal) |
| Permitted trailer load with brakes (12%) | 6577 kg (14499.8 lbs) |
| Length | 5982 mm (235.51 in) |
| Width including mirrors | 2076 mm (81.73 in) |
| Height | 2056 mm (80.94 in) |
| Wheelbase | 3595 mm (141.54 in) |
| Front track | 1731 mm (68.15 in) |
| Rear (Back) track | 1736 mm (68.35 in) |
| Ride height (ground clearance) | 285 mm (11.22 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 |
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 direct fuel injection and variable valve timing (VVT). The direct injection system optimizes combustion efficiency and power delivery, while VVT enhances low-end torque and improves overall fuel economy. 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 contribute to its reputation for durability. Power is transmitted to all four wheels through a six-speed Hydra-Matic automatic transmission. This transmission is known for its smooth shifting and ability to handle the high torque output of the 6.6L V8. The transmission is electronically controlled, adapting shift points based on driving conditions and throttle input.
Driving Characteristics
The 401 hp/464 lb-ft configuration of the Sierra 3500HD delivers substantial performance, particularly when it comes to towing and hauling. While not as quick as lighter-duty trucks or those equipped with the optional Duramax diesel engine, the 6.6L V8 provides ample power for everyday driving and demanding work tasks. The automatic transmission contributes to ease of use, especially in stop-and-go traffic or when navigating challenging terrain. The gear ratios are optimized for towing, providing strong low-end torque for pulling heavy loads. Compared to the diesel variants, this gasoline engine offers a more familiar driving experience with a traditional V8 sound and feel. However, it lacks the diesel’s exceptional low-end torque and fuel efficiency.
Equipment & Trim Levels
The Regular Cab Long Bed 3500HD with the 6.6L V8 typically served as the entry point into the Sierra HD lineup. Standard equipment included air conditioning, a basic infotainment system with a touchscreen display, and a rearview camera. The interior featured durable cloth upholstery and vinyl flooring, reflecting its work-truck focus. Optional extras included upgraded infotainment systems with navigation, leather upholstery, power-adjustable seats, and a variety of trailering packages. The trim level could vary, but generally offered a balance between functionality and basic comfort. Higher trim levels added features like chrome exterior accents, heated seats, and premium audio systems.
Chassis & Braking
The Sierra 3500HD’s chassis is built for heavy-duty use, featuring a fully boxed frame and robust suspension components. The front suspension utilizes coil springs and a double wishbone design, while the rear suspension employs 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 heavy loads. An Anti-lock Braking System (ABS) is standard. The rear axle is a solid axle, designed for durability and strength. Steering is hydraulic, providing a responsive and predictable feel.
Market Reception & Comparison
The 6.6L V8-powered Sierra 3500HD received generally positive reviews for its capability and value. Critics praised its strong towing capacity and relatively affordable price point compared to diesel models. However, fuel economy was a common concern, as the gasoline engine is less efficient than the Duramax diesel. Compared to the diesel variants, the 6.6L V8 offered a lower initial cost but higher operating costs due to fuel consumption. The gasoline engine was often favored by buyers who did not require the extreme towing capacity of the diesel and preferred the simplicity and lower maintenance costs of a gasoline engine.
Legacy
The 6.6L V8 engine in the GMTT1XX Sierra 3500HD has proven to be a reliable and durable powertrain. While not as sought-after as the Duramax diesel, these trucks remain popular in the used market, particularly among buyers looking for a capable and affordable heavy-duty truck. The engine’s relatively simple design and robust construction contribute to its longevity. Common maintenance items include regular oil changes and spark plug replacements. Overall, the 2020-2023 Sierra 3500HD with the 6.6L V8 represents a solid and dependable work truck that continues to provide value to its owners.
