The GMC Sierra 3500HD IV (GMTK2XX) Crew Cab Standard Box with the 6.0L V8 engine and 4WD automatic transmission, offered with a Compressed Natural Gas (CNG) conversion, represents a specific configuration within the fourth generation of GMC’s heavy-duty pickup truck line. Produced for the 2015 and 2016 model years, this variant aimed to provide a balance of capability, comfort, and alternative fuel operation for both commercial and personal use. It occupied a mid-range position within the Sierra 3500HD lineup, offering a step up in power and towing capacity from the base engine options while remaining below the more expensive diesel-powered models.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD IV (GMTK2XX) Crew Cab Standard Box |
| Type (Engine) | 6.0 V8 (301 Hp) 4WD 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%) | 3946 kg / 8699.44 lbs. |
| Length | 6083 mm / 239.49 in. |
| Width including mirrors | 2045 mm / 80.51 in. |
| Height | 1985 mm / 78.15 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) | 214 mm / 8.43 in. |
| Minimum turning circle (turning diameter) | 15.8 m / 51.84 ft. |
| 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, 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 |
INTRODUCTION
The 2015-2016 GMC Sierra 3500HD Crew Cab with the 6.0L V8 and 4WD automatic transmission, further equipped with a CNG system, was part of the GMTK2XX platform generation. This generation represented a significant step forward in heavy-duty truck design, focusing on increased capability, refined interiors, and improved technology. The Crew Cab configuration offered a spacious interior, making it suitable for both work and family use. The addition of a CNG system catered to fleets and individuals seeking to reduce their reliance on gasoline and lower emissions, though it came with compromises in fuel tank capacity and range.
Powertrain & Engine Architecture
At the heart of this Sierra 3500HD variant lies the Vortec LC8 6.0-liter V8 engine. This engine is a member of GM’s small-block V8 family, known for its durability 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. The engine also incorporates Overhead Valve (OHV) valve actuation with Variable Valve Timing (VVT) on the intake side, optimizing performance and efficiency. The 6L90 six-speed automatic transmission, known as the Hydra-Matic, was the standard transmission pairing. This transmission is electronically controlled and designed to handle the high torque output of the 6.0L V8. The CNG system is a bi-fuel setup, meaning the truck can run on either gasoline or CNG, switching between the two fuels as needed.
Driving Characteristics
The 301 horsepower and 333.38 lb-ft of torque provided by the 6.0L V8, when coupled with the six-speed automatic, delivered adequate performance for most heavy-duty tasks. However, it wasn’t the quickest or most powerful configuration available in the Sierra 3500HD lineup. Compared to the 6.6L Duramax diesel engine, the 6.0L V8 offered significantly less torque, impacting towing capacity and acceleration, especially when heavily loaded. The automatic transmission provided smooth shifts, but could sometimes feel hesitant during quick acceleration. The CNG system slightly reduced overall power output when running on CNG compared to gasoline. The 4WD system provided enhanced traction in challenging conditions, making it suitable for off-road use and inclement weather.
Equipment & Trim Levels
The Sierra 3500HD Crew Cab with the 6.0L V8 and CNG system typically came standard with features such as air conditioning, power windows and locks, a basic audio system, and a tilt steering wheel. Higher trim levels, such as SLE and SLT, added features like leather upholstery, heated seats, a premium audio system, navigation, and advanced safety technologies. The CNG system itself was often installed by upfitters, meaning the specific components and features could vary. Standard safety features included ABS brakes and a suite of airbags.
Chassis & Braking
The Sierra 3500HD featured a robust chassis designed to handle heavy loads. The front suspension utilized coil springs and a double wishbone design, while the rear suspension employed a traditional leaf spring setup. This configuration provided a comfortable ride while maintaining excellent load-carrying capacity. Brakes consisted of ventilated discs on all four wheels, providing ample stopping power. The front brakes measured 350x40mm, while the rear brakes were slightly larger at 373x34mm. An Anti-lock Braking System (ABS) was standard, enhancing safety during emergency braking situations.
Market Reception & Comparison
The 6.0L V8/automatic combination in the Sierra 3500HD was generally well-received as a capable and affordable option for those who didn’t require the ultimate towing capacity of the diesel models. Critics noted its smooth ride and comfortable interior. However, it was often criticized for its lower fuel economy compared to the diesel engine, and its reduced power output. The CNG conversion was seen as a positive step towards alternative fuels, but its limited refueling infrastructure and reduced range were drawbacks. Compared to the 6.6L Duramax diesel, the 6.0L V8 offered a lower purchase price but significantly higher operating costs, especially when factoring in fuel consumption.
Legacy
The 2015-2016 GMC Sierra 3500HD with the 6.0L V8 and CNG system represents a transitional period in the heavy-duty truck market. While the 6.0L V8 engine itself is known for its reliability, the CNG system adds a layer of complexity that requires specialized maintenance. On the used car market, these trucks are generally available at lower prices than their diesel counterparts. The longevity of the CNG system depends heavily on its maintenance and the quality of the original installation. Overall, this variant remains a viable option for those seeking a capable and affordable heavy-duty truck with the added benefit of alternative fuel capability.
