The GMC Sierra 2500HD V (GMTT1XX) Regular Cab Long Bed, equipped with the 6.6-liter V8 engine producing 401 horsepower and paired with an automatic transmission, represents a significant offering in the heavy-duty pickup truck segment. Produced from 2020 to 2023, this configuration catered to buyers needing substantial towing and hauling capabilities in a no-frills, work-oriented package. It falls within the fourth generation of the Sierra 2500HD and 3500HD trucks, designated GMTT1XX, which introduced a more robust and technologically advanced platform compared to its predecessors.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD V (GMTT1XX) Regular 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 | 2 |
| Doors | 2 |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 6.9 kg/Hp, 144.8 Hp/tonne |
| Weight-to-torque ratio | 4.4 kg/Nm, 227.2 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 | 2769 kg, 6104.6 lbs |
| Max. weight | 4536 kg, 10000.17 lbs |
| Max load | 1767 kg, 3895.57 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 | 2030 mm, 79.92 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) | 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 | 235/80 R17; 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 2500HD 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 L8T utilizes direct fuel injection, contributing 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 prioritize durability and reliability over outright performance. The engine is longitudinally mounted in the chassis, driving the rear wheels. Paired with the engine is a six-speed Hydra-Matic automatic transmission, chosen for its durability and ability to handle the high torque output of the V8. This transmission is designed for smooth shifting and reliable operation under heavy loads.
Driving Characteristics
The 6.6L V8 and six-speed automatic combination in the Sierra 2500HD delivers a driving experience focused on capability rather than sportiness. Acceleration is adequate for everyday driving, but the truck truly shines when towing or hauling heavy loads. The automatic transmission provides smooth shifts, and the gear ratios are optimized for maximizing torque at lower speeds. Compared to potential diesel variants, this gasoline engine offers quicker acceleration at lower weights, but sacrifices fuel economy and ultimate towing capacity. The relatively simple automatic transmission, while reliable, doesn’t offer the same level of responsiveness or gear selection as more modern transmissions found in some competitors.
Equipment & Trim Levels
The Regular Cab Long Bed configuration of the Sierra 2500HD typically served as the entry point into the heavy-duty lineup. Standard equipment generally included basic features like air conditioning, a basic infotainment system with a touchscreen display, and vinyl upholstery. The interior was functional and durable, designed to withstand the rigors of work-truck use. Optional extras included upgraded infotainment systems with navigation, cloth or leather upholstery, power windows and locks, and various towing packages. This specific trim level was often chosen by customers prioritizing affordability and functionality over luxury features.
Chassis & Braking
The Sierra 2500HD’s chassis is built around a fully boxed frame, providing a solid foundation for heavy-duty use. The front suspension utilizes a coil spring, double wishbone setup with a transverse stabilizer bar, while the rear suspension employs a traditional leaf spring design. This configuration prioritizes load-carrying capacity and durability. Braking duties are handled by ventilated disc brakes at all four corners, with larger rotors at the front (355×40 mm) compared to the rear (360×34 mm). An Anti-lock Braking System (ABS) is standard. The steering system is a hydraulic rack-and-pinion setup, providing adequate steering feel and control.
Market Reception & Comparison
The 2500HD with the 6.6L V8 and automatic transmission received generally positive reviews for its capability and reliability. Critics noted its strong towing capacity and durable powertrain. However, fuel economy was a common criticism, as the gasoline engine is less efficient than the available diesel options. Compared to the Duramax diesel variants, this configuration offered a lower price point but sacrificed fuel efficiency and maximum towing capacity. The gasoline engine was often favored by buyers who didn’t require the extreme towing capabilities of the diesel and preferred the lower initial cost.
Legacy
The 6.6L V8 in the GMTT1XX Sierra 2500HD has proven to be a relatively reliable powertrain. While not as fuel-efficient as diesel alternatives, it has earned a reputation for durability and relatively low maintenance costs. In the used car market, these trucks remain popular among buyers seeking a capable and affordable heavy-duty pickup. Common maintenance items include regular oil changes, coolant flushes, and inspection of the suspension and braking components. The simplicity of the gasoline engine and automatic transmission contributes to its long-term reliability and ease of repair, making it a viable option for those seeking a workhorse truck that can withstand years of use.
