The GMC Sierra 3500HD, specifically the V (GMTT1XX) Double Cab Long Bed configuration with the 6.6-liter V8 engine producing 401 horsepower, represents a significant offering in the heavy-duty pickup truck segment. Produced from 2020 through 2023, this variant caters to buyers needing substantial towing and payload capacity, blending robust capability with a degree of passenger comfort. It occupies a position within the Sierra 3500HD lineup as a versatile work truck, appealing to both commercial users and individuals requiring serious hauling power. The “V” designation refers to the GMTT1XX platform, representing the fifth generation of the heavy-duty Chevrolet/GMC trucks.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD V (GMTT1XX) Double Cab Long Bed |
| Type (Engine) | 6.6 V8 (401 Hp) 4WD DRW 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 | 8.2 kg/Hp, 121.8 Hp/tonne |
| Weight-to-torque ratio | 5.2 kg/Nm, 191 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 | 3293 kg (7259.82 lbs) |
| Max. weight | 6350 kg (13999.35 lbs) |
| Max load | 3057 kg (6739.53 lbs) |
| Fuel tank capacity | 136 l (35.93 US gal | 29.92 UK gal) |
| Permitted trailer load with brakes (12%) | 7434 kg (16389.16 lbs) |
| Length | 6514 mm (256.46 in) |
| Width including mirrors | 2457 mm (96.73 in) |
| Height | 2037 mm (80.2 in) |
| Wheelbase | 4127 mm (162.48 in) |
| Front track | 1731 mm (68.15 in) |
| Rear (Back) track | 1905 mm (75 in) |
| Ride height (ground clearance) | 264 mm (10.39 in) |
| Drivetrain Architecture | All wheel drive (4×4). ICE drives rear wheels, front wheels engaged via clutch. |
| 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, 355×40 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 the Sierra 3500HD V is the 6.6-liter L8T V8 gasoline engine. This engine is a naturally aspirated, overhead valve (OHV) design featuring variable valve timing (VVT). Direct fuel injection is employed to optimize combustion efficiency and power output. The engine produces 401 horsepower at 5200 rpm and 464 lb-ft of torque at 4000 rpm. The Hydra-Matic 6L90 six-speed automatic transmission is standard, chosen for its durability and ability to handle the engine’s substantial torque. This transmission features electronically controlled shifts and a tow/haul mode for optimized performance when towing heavy loads. The engine’s longitudinal mounting and rear-wheel-drive bias, coupled with a selectable four-wheel-drive system, provide excellent traction in various conditions.
Driving Characteristics
The 6.6L V8 and six-speed automatic combination delivers a robust driving experience, prioritizing capability over outright speed. Acceleration is adequate for daily driving, but the truck truly shines when put to work. The automatic transmission is tuned for smooth shifts and predictable behavior, especially when towing. The tow/haul mode alters shift points to maintain engine braking on descents and reduce gear hunting when climbing hills. Compared to the available Duramax diesel engine, the gasoline V8 offers quicker throttle response and a quieter cabin experience, but sacrifices fuel economy and ultimate towing capacity. The gear ratios are optimized for pulling power, with a relatively low first gear for launching heavy loads.
Equipment & Trim Levels
The Sierra 3500HD V Double Cab Long Bed typically came standard with features like air conditioning, power windows and locks, a basic infotainment system with a touchscreen display, and a rearview camera. The Double Cab configuration provides comfortable seating for five passengers. Higher trim levels, such as the SLT and Denali, added features like leather upholstery, heated and ventilated seats, a premium audio system, and advanced safety technologies like lane departure warning and blind-spot monitoring. Optional extras included a power sunroof, navigation system, and various towing packages.
Chassis & Braking
The Sierra 3500HD utilizes a robust body-on-frame construction, providing a solid foundation for heavy-duty work. The front suspension consists of coil springs and a double wishbone setup with a transverse stabilizer bar. The rear suspension employs a traditional leaf spring design, optimized for load-carrying capacity. Braking duties are handled by ventilated disc brakes on all four wheels, measuring 355x40mm. An Anti-lock Braking System (ABS) is standard. The truck’s steering system utilizes a cone worm and recirculation ball mechanism with hydraulic power assist, providing a firm and responsive feel.
Market Reception & Comparison
The GMC Sierra 3500HD V with the 6.6L gasoline engine received generally positive reviews, particularly from buyers who prioritized affordability and simplicity over the complexity and higher cost of a diesel engine. Critics noted the engine’s ample power and torque for most towing and hauling tasks, but acknowledged its lower fuel economy compared to the Duramax diesel. Compared to the diesel variants, the gasoline engine was seen as a more accessible option for those who didn’t require the absolute maximum towing capacity. The Sierra 3500HD also faced competition from Ford’s Super Duty and Ram’s heavy-duty trucks, each offering similar capabilities and features.
Legacy
The L8T 6.6L V8 engine, paired with the 6L90 transmission, has proven to be a relatively reliable powertrain in the Sierra 3500HD. While not as renowned for longevity as the Duramax diesel, it has generally demonstrated good durability with proper maintenance. On the used car market, these trucks represent a good value for buyers seeking a capable heavy-duty pickup without the premium price tag of a diesel model. Common maintenance items include regular oil changes, transmission fluid flushes, and inspection of the cooling system. Overall, the Sierra 3500HD V remains a popular choice for those needing a workhorse truck that can handle demanding tasks.
