The GMC Sierra 3500HD IV, specifically the Crew Cab Standard Box configuration with the 6.0-liter V8 engine paired with an automatic transmission and capable of running on Compressed Natural Gas (CNG), was produced for the 2015 and 2016 model years. This variant represented a heavy-duty pickup truck option aimed at buyers needing substantial towing and payload capacity, with the added flexibility of alternative fuel operation. It falls within the fourth generation (GMTK2XX) of the Sierra 3500HD line, known for its increased strength and refinement compared to previous generations.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD IV (GMTK2XX) Crew Cab Standard Box |
| Type (Engine) | 6.0 V8 (301 Hp) Automatic CNG |
| Start of production | 2015 |
| End of production | 2016 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Petrol / CNG |
| Power | 301 Hp @ 5000 rpm |
| Power per litre | 50.4 Hp/l |
| Torque | 452 Nm @ 4200 rpm / 333.38 lb.-ft. @ 4200 rpm |
| Maximum engine speed | 6000 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | Vortec LC8 |
| Engine displacement | 5967 cm3 / 364.13 cu. in. |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 101.6 mm / 4 in. |
| Piston Stroke | 92 mm / 3.62 in. |
| Compression ratio | 9.6:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Naturally aspirated engine |
| Valvetrain | OHV, VVT |
| Engine oil capacity | 5.7 l / 6.02 US qt | 5.02 UK qt |
| Coolant | 15.5 l / 16.38 US qt | 13.64 UK qt |
| Fuel tank capacity | 136 l / 35.93 US gal | 29.92 UK gal |
| CNG cylinder capacity | 67 kg |
| Permitted trailer load with brakes (12%) | 4082 kg / 8999.27 lbs. |
| Length | 6083 mm / 239.49 in. |
| Width including mirrors | 2045 mm / 80.51 in. |
| Height | 1990 mm / 78.35 in. |
| Wheelbase | 3904 mm / 153.7 in. |
| Front track | 1748 mm / 68.82 in. |
| Rear (Back) track | 1709 mm / 67.28 in. |
| Ride height (ground clearance) | 218 mm / 8.58 in. |
| Minimum turning circle (turning diameter) | 15.8 m / 51.84 ft. |
| 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, 350×40 mm |
| Rear brakes | Ventilated discs, 373×34 mm |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Cone worm with recirculation balls |
| Tires size | 235/80 R17; 265/70 R18 |
| Wheel rims size | 7.5J x 17; 8J x 18 |
Powertrain & Engine Architecture
At the heart of this Sierra 3500HD variant lies the Vortec LC8 engine, a 6.0-liter (364 cubic inches) V8. This engine is a member of the Vortec family, known for its robust construction and relatively simple design. It features a cast iron block and aluminum cylinder heads. The LC8 utilizes a multi-port fuel injection system, delivering fuel directly to each cylinder for efficient combustion. The overhead valve (OHV) valvetrain, coupled with variable valve timing (VVT), helps optimize performance and fuel economy across a range of engine speeds. The engine’s ability to run on CNG is achieved through a dedicated fuel system that supplements or replaces gasoline operation. The Hydra-Matic 6L90 six-speed automatic transmission was the standard pairing for this engine, providing smooth shifting and optimized gear ratios for heavy-duty applications.
Driving Characteristics
The 301 horsepower and 333 lb-ft of torque produced by the 6.0L V8, while substantial, positioned this Sierra 3500HD as a mid-range offering within the lineup. Compared to the available Duramax diesel engines, it offered less low-end torque, making it less ideal for extremely heavy towing. However, it provided a more responsive and familiar driving experience for those accustomed to gasoline engines. The six-speed automatic transmission was well-matched to the engine’s powerband, offering adequate acceleration and smooth cruising. The CNG capability, while reducing emissions, could slightly impact overall power output depending on the CNG fuel quality and system calibration. The truck’s substantial weight and heavy-duty suspension resulted in a firm ride, prioritizing stability and load-carrying capacity over comfort.
Equipment & Trim Levels
The Crew Cab configuration offered spacious seating for five passengers, making it suitable for both work and family use. Standard features typically included air conditioning, power windows and locks, a basic audio system, and vinyl upholstery. Higher trim levels, such as the SLT and Denali, added features like leather upholstery, heated seats, a premium audio system, and advanced infotainment options. The CNG-equipped models often included specific gauges and indicators to monitor the CNG fuel system. Optional extras could include a navigation system, a sunroof, and various towing packages.
Chassis & Braking
The Sierra 3500HD featured a fully boxed frame designed for exceptional strength and rigidity. The front suspension utilized a coil spring, double wishbone setup with a transverse stabilizer bar, while the rear suspension employed a traditional leaf spring design. This combination provided a robust and durable suspension system capable of handling heavy loads. Braking duties were handled by ventilated disc brakes on all four wheels, providing ample stopping power. An Anti-lock Braking System (ABS) was standard, enhancing safety and control during emergency braking situations. The rear axle ratios were typically geared towards towing and hauling, prioritizing torque multiplication over fuel efficiency.
Market Reception & Comparison
The GMC Sierra 3500HD with the 6.0L V8 and CNG capability was generally well-received by buyers seeking a versatile and capable heavy-duty truck. Critics noted its strong towing capacity and comfortable interior, but also pointed out that the gasoline engine lacked the low-end grunt of the Duramax diesel. The CNG option was seen as a positive step towards reducing emissions and fuel costs, particularly for fleet operators. Compared to the diesel variants, this configuration offered a lower initial purchase price but potentially higher long-term fuel costs depending on gasoline and CNG prices. Reliability was generally good, with the Vortec LC8 engine proving to be a durable and dependable powerplant.
Legacy
The 2015-2016 GMC Sierra 3500HD with the 6.0L V8 and CNG option represents a unique offering in the heavy-duty truck market. While not as popular as the diesel-powered models, it provided a viable alternative for buyers seeking a gasoline-powered truck with the added benefit of alternative fuel capability. Today, these trucks can be found on the used market at relatively affordable prices. The Vortec LC8 engine is known for its longevity and relatively simple maintenance requirements, making it a good choice for buyers seeking a reliable and capable work truck. However, potential buyers should be aware of the specific maintenance requirements of the CNG fuel system and ensure it is properly inspected and maintained.
