The Chevrolet Silverado 3500 HD III (K2XX) Regular Cab Long Box, equipped with the 6.0-liter V8 engine and a six-speed automatic transmission, and capable of running on Compressed Natural Gas (CNG), was a heavy-duty pickup truck produced by Chevrolet for the 2015 and 2016 model years. This variant occupied a significant position within the K2XX Silverado 3500 HD lineup, offering a balance between capability, fuel flexibility, and work-oriented practicality. It was designed primarily for the North American market, catering to customers needing substantial towing and hauling capacity, particularly in industries exploring alternative fuels.
Technical Specifications
| Brand | Chevrolet |
| Model | Silverado 3500 HD |
| Generation | Silverado 3500 HD III (K2XX) Regular Cab Long 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 | 2 |
| Doors | 2 |
| 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%) | 4264 kg / 9400.51 lbs. |
| Length | 5699 mm / 224.37 in. |
| Width including mirrors | 2035 mm / 80.12 in. |
| Height | 1977 mm / 77.83 in. |
| Wheelbase | 3393 mm / 133.58 in. |
| Front track | 1748 mm / 68.82 in. |
| Rear (Back) track | 1709 mm / 67.28 in. |
| Ride height (ground clearance) | 229 mm / 9.02 in. |
| Minimum turning circle (turning diameter) | 14 m / 45.93 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 | Independent torsion bar, double wishbone |
| Rear suspension | Rigid axle suspension, Leaf spring |
| Front brakes | Ventilated discs, 350×40 mm |
| Rear brakes | Ventilated discs, 360×34 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 Silverado 3500 HD variant lies the Vortec LC8 engine, a 6.0-liter (364 cubic inches) V8. This engine is a member of Chevrolet’s Vortec family, known for its robust construction and reliable performance. The LC8 features a cast iron block and aluminum cylinder heads, incorporating a 9.6:1 compression ratio and a multi-port fuel injection system. The overhead valve (OHV) valvetrain, coupled with variable valve timing (VVT), optimizes power delivery across the engine’s operating range. The engine produces 301 horsepower at 5000 rpm and 452 Nm (333.38 lb-ft) of torque at 4200 rpm. The engine was designed to run on gasoline, but this specific configuration was also factory-equipped to operate on Compressed Natural Gas (CNG), offering an alternative fuel option. The six-speed Hydra-Matic automatic transmission was the sole transmission offering for this configuration, providing smooth and efficient gear changes. The transmission was tuned for heavy-duty applications, with gear ratios optimized for towing and hauling.
Driving Characteristics
The 6.0L V8 with the six-speed automatic provided a solid, if not particularly sporty, driving experience. The emphasis was clearly on capability rather than acceleration. While the engine delivered adequate power for everyday driving, its strength lay in its ability to handle heavy loads. The automatic transmission, while smooth, wasn’t geared for rapid acceleration; instead, it prioritized maintaining engine RPMs within the optimal torque band for towing. Compared to the available diesel options (like the Duramax), this gasoline/CNG variant offered less torque, resulting in a lower maximum towing capacity. However, it was generally more responsive than lower-powered gasoline engines in the lineup. The CNG capability added a unique dimension, allowing operators to take advantage of potentially lower fuel costs and reduced emissions where CNG infrastructure was available.
Equipment & Trim Levels
The Silverado 3500 HD III Regular Cab Long Box with the 6.0L V8/Automatic/CNG powertrain was typically offered in work-truck focused trim levels. Standard features included a basic audio system, vinyl upholstery, air conditioning, and power windows and locks. The interior was functional and durable, designed to withstand the rigors of commercial use. Optional extras included upgraded audio systems, cruise control, and various towing packages. The Regular Cab configuration meant a focus on practicality and affordability, lacking the passenger space of extended or crew cab models. The long box provided ample cargo space, making it suitable for hauling large or bulky items.
Chassis & Braking
The Silverado 3500 HD featured a robust chassis designed to handle heavy payloads. The front suspension utilized an independent torsion bar setup with double wishbones, providing a comfortable ride while maintaining stability. The rear suspension employed a traditional leaf spring design, known for its durability and load-carrying capacity. Braking duties were handled by ventilated disc brakes on all four wheels, with ABS (Anti-lock Braking System) as standard equipment. The rear brakes were slightly larger (360x34mm) than the front (350x40mm) to accommodate the increased weight typically carried in the bed. Steering was accomplished via a cone worm with recirculation balls system.
Market Reception & Comparison
The 6.0L V8/Automatic/CNG Silverado 3500 HD was generally well-received by those seeking a heavy-duty truck with alternative fuel capabilities. Critics noted its strong towing capacity and reliable powertrain. However, it was often compared unfavorably to the diesel-powered Silverado 3500 HD models, which offered significantly more torque and fuel efficiency. The gasoline/CNG variant was often seen as a more affordable entry point into the heavy-duty truck market, appealing to customers who didn’t require the ultimate in towing performance but valued the flexibility of running on CNG. Fuel economy was comparable to other gasoline-powered heavy-duty trucks, but the availability and cost of CNG varied significantly by region.
Legacy
The Vortec LC8 engine, in general, has proven to be a durable and reliable powerplant. While not without its potential issues (such as oil consumption in some cases), it is generally considered a robust engine capable of high mileage with proper maintenance. The CNG conversion, when properly maintained, adds to the engine’s longevity. Today, used examples of the 2015-2016 Silverado 3500 HD with this powertrain configuration are relatively common and can be found at reasonable prices. They represent a practical and capable option for those needing a heavy-duty truck with the added benefit of alternative fuel capability, though the availability of CNG refueling stations remains a key consideration for potential buyers.
