The GMC Sierra 2500HD V (GMTT1XX) Crew Cab Long Bed, equipped with the 6.6-liter V8 engine producing 401 horsepower, represents a significant offering in the heavy-duty pickup truck segment. Produced from 2020 to 2023, this variant occupied a sweet spot in the Sierra 2500HD lineup, balancing substantial capability with a degree of refinement suitable for both work and personal use. It was positioned as a step up from the base engine options, appealing to buyers needing more power for towing and hauling, while remaining more accessible than the top-tier diesel offerings. This generation Sierra 2500HD, built on the GMTT1XX platform, aimed to improve upon its predecessor with enhanced technology, increased interior space, and a more robust chassis.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD V (GMTT1XX) Crew Cab Long Bed |
| Type (Engine) | 6.6 V8 (401 Hp) 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 | 7.5 kg/Hp, 133.3 Hp/tonne |
| Weight-to-torque ratio | 4.8 kg/Nm, 209 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 | 3009 kg, 6633.71 lbs |
| Max. weight | 4672 kg, 10300 lbs |
| Max load | 1663 kg, 3666.29 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 | 6759 mm, 266.1 in |
| Width including mirrors | 2079 mm, 81.85 in |
| Height | 2023 mm, 79.65 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) | 256 mm, 10.08 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, 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 2020-2023 GMC Sierra 2500HD Crew Cab Long Bed with the 6.6L V8 and automatic transmission is a heavy-duty pickup truck designed for demanding tasks. This model year represents the beginning of the GMTT1XX generation, a significant redesign focused on improving capability, comfort, and technology. The Crew Cab configuration provides ample passenger space, while the Long Bed offers substantial cargo capacity. This particular variant, with its 401 horsepower gasoline engine and six-speed automatic transmission, aimed to provide a balance between power, efficiency, and affordability within the Sierra 2500HD range.
Powertrain & Engine Architecture
At the heart of this Sierra 2500HD lies the GM 6.6-liter L8T V8 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 fuel delivery for improved power and efficiency, while VVT adjusts valve timing to enhance performance across the engine’s operating range. 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 reliability. The engine is paired with a six-speed Hydra-Matic automatic transmission, known for its durability and smooth shifting. This transmission is specifically tuned for heavy-duty applications, providing appropriate gear ratios for towing and hauling.
Driving Characteristics
The 6.6L V8 and six-speed automatic combination delivers a capable, if not overly sporty, driving experience. While not as quick as some lighter-duty pickups, the Sierra 2500HD provides ample power for accelerating with a load or tackling steep grades. The automatic transmission shifts smoothly and predictably, and the gear ratios are well-suited for both highway cruising and low-speed towing. Compared to the available diesel engine options, the gasoline V8 offers quicker acceleration at lower speeds but sacrifices fuel economy and ultimate towing capacity. Compared to a manual transmission equipped version (which wasn’t widely offered), the automatic provides greater convenience, especially in stop-and-go traffic or when towing. The truck’s substantial weight is noticeable, but the well-tuned suspension helps to mitigate body roll and provide a relatively comfortable ride, even when unladen.
Equipment & Trim Levels
The Sierra 2500HD Crew Cab Long Bed with the 6.6L V8 was typically offered in SLE, Elevation, and AT4 trim levels. Standard equipment on the SLE trim included features like an 8-inch touchscreen infotainment system with Apple CarPlay and Android Auto compatibility, a rearview camera, and keyless entry. The Elevation trim added more aggressive styling cues, while the AT4 trim focused on off-road capability with features like skid plates and an upgraded suspension. Optional extras included a larger touchscreen display, a premium audio system, leather upholstery, heated and ventilated front seats, and a suite of advanced safety features such as adaptive cruise control and lane departure warning. Interior materials varied depending on the trim level, with higher trims offering more luxurious appointments.
Chassis & Braking
The Sierra 2500HD features a fully boxed frame designed for strength and rigidity. The front suspension utilizes coil springs and a double wishbone design, while the rear suspension employs a traditional leaf spring setup. This configuration provides a good balance between ride comfort and load-carrying capacity. Braking duties are handled by ventilated disc brakes at all four corners, providing ample stopping power even when heavily loaded. The front brakes measure 355x40mm, while the rear brakes are 360x34mm. An Anti-lock Braking System (ABS) is standard equipment. The steering system utilizes a hydraulic power steering system, providing a responsive and predictable feel.
Market Reception & Comparison
Critics generally praised the 2020-2023 GMC Sierra 2500HD for its improved interior, enhanced technology, and robust construction. The 6.6L V8 engine was considered a capable performer, offering a good balance of power and refinement. However, some reviewers noted that the gasoline engine’s fuel economy lagged behind that of the diesel options. Compared to competitors like the Ford Super Duty and Ram 2500, the Sierra 2500HD was often seen as offering a more refined driving experience and a more modern interior. The gasoline engine was often favored by buyers who didn’t require the ultimate towing capacity of the diesel but still wanted a powerful and capable truck.
Legacy
The 6.6L L8T V8 engine paired with the six-speed automatic transmission has proven to be a relatively reliable powertrain. While not immune to the occasional issue, these engines are generally known for their durability and longevity. In the used car market, the 2020-2023 GMC Sierra 2500HD with this powertrain combination remains a popular choice for buyers seeking a capable and dependable heavy-duty pickup truck. Maintenance costs are generally reasonable, and parts availability is good. The combination of capability, comfort, and reliability ensures that this Sierra 2500HD variant will continue to be a sought-after vehicle for years to come.
