The GMC Sierra 2500HD V (GMTT1XX) Double Cab Standard 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 strong position within the fourth generation of the Sierra 2500HD lineup, catering to buyers needing substantial towing and hauling capabilities without sacrificing everyday usability. It was positioned as a workhorse, bridging the gap between the base model and the more luxurious, higher-trim level options.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD V (GMTT1XX) Double Cab Standard 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 | 7.3 kg/Hp, 137.7 Hp/tonne |
| Weight-to-torque ratio | 4.6 kg/Nm, 215.9 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 | 2913 kg, 6422.07 lbs |
| Max. weight | 4559 kg, 10050.87 lbs |
| Max load | 1646 kg, 3628.81 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 | 6107 mm, 240.43 in |
| Width including mirrors | 2079 mm, 81.85 in |
| Height | 2031 mm, 79.96 in |
| Wheelbase | 3795 mm, 149.41 in |
| Front track | 1731 mm, 68.15 in |
| Rear (Back) track | 1736 mm, 68.35 in |
| Ride height (ground clearance) | 259 mm, 10.2 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 |
Powertrain & Engine Architecture
At the heart of the Sierra 2500HD is 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 fuel economy. The engine produces 401 horsepower at 5200 rpm and 464 lb-ft of torque at 4000 rpm. This power is channeled through a six-speed Hydra-Matic automatic transmission, known for its durability and smooth shifting characteristics. The transmission is calibrated to prioritize towing performance, with lower gear ratios for enhanced pulling power.
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 2500HD provides ample power for hauling heavy loads and navigating challenging terrain. The automatic transmission shifts smoothly and predictably, although it may occasionally hunt for the right gear when under heavy acceleration. The lower gear ratios contribute to strong low-end torque, making it easy to get a heavily loaded trailer moving. Compared to diesel variants, this gasoline engine offers a quieter and smoother ride, but at the expense of fuel economy and ultimate towing capacity. The manual transmission options, when available, provided a more engaging driving experience, but the automatic was favored by many for its convenience and ease of use.
Equipment & Trim Levels
The Double Cab Standard Bed configuration 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 AT4, 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, prioritizing practicality over luxury, although the materials quality was generally good for a heavy-duty truck.
Chassis & Braking
The Sierra 2500HD features a robust chassis designed to withstand heavy loads and demanding conditions. The front suspension utilizes coil springs and a double wishbone setup with a transverse stabilizer bar, while the rear suspension employs a traditional leaf spring configuration. This setup 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. An Anti-lock Braking System (ABS) is standard, enhancing safety and control during emergency braking situations. Steering is accomplished via a hydraulic power steering system, offering a responsive and precise feel.
Market Reception & Comparison
The GMC Sierra 2500HD with the 6.6L V8 and automatic transmission received generally positive reviews. Critics praised its powerful engine, smooth transmission, and comfortable ride. However, fuel economy was a common concern, as the gasoline engine is less efficient than the available diesel options. Compared to the Duramax diesel engine, the 6.6L V8 offered a lower price point and simpler maintenance requirements, making it an attractive option for buyers who didn’t require the ultimate towing capacity. The Ford Super Duty and Ram 2500/3500 were the Sierra’s primary competitors, each offering similar capabilities and features.
Legacy
The L8T 6.6L V8 engine, paired with the Hydra-Matic automatic transmission, has proven to be a relatively reliable powertrain. While not immune to typical maintenance needs, such as oil changes and spark plug replacements, it generally exhibits good longevity. In the used car market, these Sierra 2500HD models are often sought after by buyers looking for a capable and affordable heavy-duty truck. The combination of power, durability, and relative simplicity makes it a practical choice for work and recreational use. As with any used vehicle, a thorough inspection and maintenance history review are recommended before purchase.
