The GMC Sierra 2500HD V (GMTT1XX) Crew Cab Standard Bed, equipped with the 6.6-liter V8 engine producing 401 horsepower, represents GMC’s entry into the heavy-duty pickup truck segment. Produced from 2020 through 2023, this variant occupied a significant position within the broader Sierra 2500HD lineup, offering a balance of capability, comfort, and technology. It was designed to cater to owners needing substantial towing and payload capacity without necessarily requiring the ultimate performance of higher-trim models. This generation Sierra 2500HD aimed to improve upon its predecessor with enhanced interior refinement, updated technology, and increased capability.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD V (GMTT1XX) Crew Cab Standard Bed |
| Type (Engine) | 6.6 V8 (401 Hp) 4WD Automatic |
| Start of production | 2020 |
| End of production | 2023 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 7.7 kg/Hp, 129.6 Hp/tonne |
| Weight-to-torque ratio | 4.9 kg/Nm, 203.2 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 | 3095 kg (6823.31 lbs) |
| Max. weight | 4750 kg (10471.96 lbs) |
| Max load | 1655 kg (3648.65 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 | 6352 mm (250.08 in) |
| Width including mirrors | 2079 mm (81.85 in) |
| Height | 2027 mm (79.8 in) |
| Wheelbase | 4037 mm (158.94 in) |
| Front track | 1731 mm (68.15 in) |
| Rear (Back) track | 1736 mm (68.35 in) |
| Ride height (ground clearance) | 257 mm (10.12 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 |
Introduction
The GMC Sierra 2500HD V (GMTT1XX) Crew Cab Standard Bed with the 6.6L V8 engine and 4WD automatic transmission, launched in 2020, represented a significant update to GMC’s heavy-duty truck offerings. Built on the GMTT1XX platform, this truck aimed to provide a robust and capable workhorse for owners needing substantial towing and hauling capacity. The Crew Cab configuration offered increased passenger space, making it suitable for both work and family use. This particular variant served as a strong mid-range option, positioned between the base model and the more powerful diesel-powered trims.
Powertrain & Engine Architecture
At the heart of this Sierra 2500HD 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 efficiency and power delivery. The engine produces 401 horsepower at 5200 rpm and 629 Nm (463.93 lb-ft) of torque at 4000 rpm. The engine’s robust construction and relatively simple design contribute to its reliability. The powertrain is paired with a six-speed Hydra-Matic automatic transmission, chosen for its durability and ability to handle the engine’s substantial torque output. This transmission is electronically controlled, offering smooth shifting and optimized gear selection for various driving conditions.
Driving Characteristics
The 6.6L V8 and six-speed automatic combination delivers a capable, though not exceptionally quick, driving experience. Acceleration is adequate for everyday driving and towing, but it doesn’t offer the briskness of some competitors with smaller displacement, turbocharged engines. The automatic transmission is well-tuned, providing smooth shifts and holding gears appropriately during towing. The gear ratios are optimized for hauling, prioritizing low-end torque over high-speed acceleration. Compared to the diesel variants, this gasoline engine is noticeably quieter and smoother, but it lacks the diesel’s immense low-end torque. Compared to a manual transmission equipped version (if available), the automatic offers greater convenience, especially in stop-and-go traffic and during long-distance towing.
Equipment & Trim Levels
The Sierra 2500HD V (GMTT1XX) Crew Cab Standard Bed 6.6 V8 4WD Automatic typically came standard with features such as air conditioning, power windows and locks, a basic infotainment system with a touchscreen display, and a rearview camera. The Crew Cab configuration provided ample space for five passengers. Higher trim levels offered upgrades like leather upholstery, heated and ventilated front seats, a premium sound system, and advanced safety features like blind-spot monitoring and rear cross-traffic alert. Optional extras included a trailer brake controller, a bed liner, and various appearance packages.
Chassis & Braking
The Sierra 2500HD features a robust chassis designed to handle heavy loads. 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, 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 cone worm with recirculation balls, providing a solid and predictable feel.
Market Reception & Comparison
Critics generally praised the Sierra 2500HD for its comfortable ride, spacious interior, and strong towing capabilities. However, the 6.6L V8 engine was sometimes criticized for its fuel economy compared to the diesel options. The gasoline engine offered a lower initial cost but resulted in higher fuel expenses, especially when towing heavy loads. Compared to the Duramax diesel engine, the 6.6L V8 provided less torque and lower fuel efficiency, but it was quieter and simpler to maintain. The gasoline engine appealed to buyers who prioritized lower upfront costs and a smoother, quieter driving experience over maximum towing capacity and fuel economy.
Legacy
The 6.6L V8 engine in the Sierra 2500HD has proven to be a relatively reliable powertrain. While not as fuel-efficient as the diesel alternatives, it has earned a reputation for durability and ease of maintenance. In the used car market, these trucks represent a good value for buyers seeking a capable heavy-duty pickup without the higher price tag of a diesel model. The GMTT1XX platform Sierra 2500HD continues to be a popular choice for those needing a robust and dependable truck for work or recreational purposes.
