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GM 6.0 Liter V8 Vortec CNG/LPG LC8 Engine

The 6.0L V8 Vortec LC8 is an engine produced by General Motors for use in its full-size heavy duty (HD) pickup trucks, vans, SUVs. It is a dedicated CNG (compressed natural gas) and LPG (liquid petroleum gas, vans only) version of the L96 engine.

Displacing 6.0 liters in a V8 configuration, the LC8 is part of the Vortec (Generation IV Small Block) engine family, which was replaced by the EcoTec3 (Generation V Small Block) engine family. The LC8 is the last Vortec engine currently in use by GM, with the EcoTec3 engine family replacing the Vortec line in all other GM vehicles.

The 6.0L’s balance of performance and efficiency features great airflow throughout. Intake flow was improved over previous engines by straightening out and optimizing the flow path from the intake manifold into the cylinder heads, while the exhaust ports are also designed for greater flow. The engine’s efficiency also optimizes emissions performance.

The engine is powerful, but delivers exceptional refinement to go with great strength. Quiet features built into the engine are complemented by an improved engine cradle and mounting system. These help reduce vibrations transmitted through the chassis and into the passenger compartment.

Engine highlights:

  • Cylinder Block and Rotating Assembly: the engine block was developed with math-based tools and data acquired in GM’s racing programs, and provides a light, rigid foundation for an impressively smooth engine. Its deep-skirt design helps maximize strength and minimize vibration. The bulkheads accommodate six-bolt, cross-bolted main-bearing caps that limit crank flex and stiffen the engine’s structure. A structural oil pan further stiffens the powertrain. Along with the rigid block, the engine’s rotating assembly was designed for optimal strength and duration complemented by features designed to make the L96 quiet and smooth. The L96 6.0L also features a heavy-duty timing chain developed expressly for quiet operation. The chain, which connects the camshaft and crankshaft, is validated for 200,000 miles of operation and fitted with a leaf-spring-type dampener.
  • High-Flow Cylinder Heads and Valvetrain: the 6.0L’s cylinder heads feature “cathedral”-shaped intake ports that promote exceptional airflow. They’re derived from the high-performance cylinder heads that were used on the “C5” Chevrolet Corvette Z06 and support great airflow at higher rpm for a broader horsepower band, along with strong, low-rpm torque. The intake ports that feed the combustion chambers, as well as the D-shaped exhaust ports, are designed for excellent high-rpm airflow.
  • Camshaft Phasing: the 6.0L features variable valve timing, maximizing engine performance for given demands and conditions. At idle, for example, the cam is at the full advanced position, allowing exceptionally smooth idling. Under other conditions, the phaser adjusts to deliver optimal valve timing for performance, drivability and fuel economy. At high rpm’s it may retard timing to maximize airflow through the engine and increase horsepower. At low rpm’s it can advance timing to increase torque. Under light loads, it can retard timing at all engine speeds to improve fuel economy.
  • E85 Flex-Fuel Capability: E85 is a clean-burning, domestically produced fuel composed of 85 percent ethanol alcohol and 15 percent gasoline. Ethanol is renewable and produces fewer emissions in the combustion process. It can be produced from various feed stocks, including corn and wheat stalks, forestry and agricultural waste and even municipal waste.
  • Advanced Electronic Throttle Control: with ETC, there is no mechanical link between the accelerator pedal and the throttle body. A sensor at the pedal measures pedal angle and sends a signal to the engine control module (ECM), which in turn directs an electric motor to open the throttle at the appropriate rate and angle. The ETC system can deliver outstanding throttle response and greater reliability than a mechanical connection.
  • Quiet Exhaust Manifolds: the exhaust manifolds were developed to improve durability and sealing and reduce operational noise. Cast nodular iron was the material of choice for its basic durability and excellent heat-management properties. The manifolds are fitted with new triple-layer heat shields fabricated from stainless steel and insulating material. The shields limit heat transfer from the engine to the engine bay, allowing the 6.0L to reach optimal operating temperature more quickly, yet reducing heat in the engine compartment once that temperature is achieved.
  • 58X Ignition System: the L96 has an advanced 58X crankshaft position encoder to ensure that ignition timing is accurate throughout its operating range. The new 58X crankshaft ring and sensor provide more immediate, accurate information on the crankshaft’s position during rotation. This allows the engine control module to adjust ignition timing with greater precision, which optimizes performance and economy. Engine starting is also more consistent in all operating conditions.
GM 6.0L V8 Vortec LC8 Engine Specs
Type: 6.0L Gen IV V8 Small Block
Displacement: 5967cc (364 ci)
Engine Orientation: Longitudinal
Compression ratio: 9.7:1
Valve configuration: Overhead valves
Valves per cylinder: 2
Assembly site: Romulus, Michigan, USA
Valve lifters: Hydraulic roller
Firing order: 1 – 8 – 7 – 2 – 6 – 5 – 4 – 3
Bore x stroke: 101.6 x 92 mm
Bore Center (mm): 111.76
Fuel system: Sequential Fuel Injection
Fuel type
Regular Unleaded
Chevrolet Silverado HD < 10,000 lbs
GMC Sierra HD < 10,000 lbs
Chevrolet Express (Cutaway)
GMC Savana (Cutaway)
Compressed Natural Gas (CNG)
Chevrolet Silverado HD < 10,000 lbs
GMC Sierra HD < 10,000 lbs
Chevrolet Express (Cargo, Cutaway)
GMC Savana (Cargo, Cutaway)
Liquified Petroleum Gas (LPG)
Chevrolet Express (Cargo, Cutaway)
GMC Savana (Cargo, Cutaway)
Horsepower hp (kW)
Chevrolet Silverado HD Gasoline: 360 hp (268 kW) @ 5400 RPM SAE Certified
GMC Sierra HD Gasoline: 360 hp (268 kW) @ 5400 RPM SAE Certified
Chevrolet Express Gasoline: 342 hp (255 kW) @ 5400 RPM SAE Certified
GMC Savana Gasoline: 342 hp (255 kW) @ 5400 RPM SAE Certified
Chevrolet Silverado HD CNG: 301 hp (225 kW) @ 5000 RPM SAE Net
GMC Sierra HD CNG: 301 hp (225 kW) @ 5000 RPM SAE Net
Chevrolet Express CNG: 282 hp (210 kW) @ 4800 RPM SAE Net
GMC Savana CNG: 282 hp (210 kW) @ 4800 RPM SAE Net
Chevrolet Express LPG: 332 hp (248 kW) @ 4800 RPM SAE Net
GMC Savana LPG: 332 hp (248 kW) @ 4800 RPM SAE Net
Torque lb.-ft. (Nm)
Chevrolet Silverado HD Gasoline: 380 lb.-ft. (515 Nm) @ 4200 RPM SAE Certified
GMC Sierra HD Gasoline: 380 lb.-ft. (515 Nm) @ 4200 RPM SAE Certified
Chevrolet Express Gasoline: 373 lb.-ft. (506 Nm) @ 4400 RPM SAE Certified
GMC Savana Gasoline: 373 lb.-ft. (506 Nm) @ 4400 RPM SAE Certified
Chevrolet Silverado HD CNG: 333 lb.-ft. (452 Nm) @ 4200 RPM SAE Net
GMC Sierra HD CNG: 333 lb.-ft. (452 Nm) @ 4200 RPM SAE Net
Chevrolet Express CNG: 320 lb.-ft. (434 Nm) @ 4400 RPM SAE Net
GMC Savana CNG: 320 lb.-ft. (434 Nm) @ 4400 RPM SAE Net
Chevrolet Express LPG: 370 lb.-ft. (501 Nm) @ 4400 RPM SAE Net
GMC Savana LPG: 370 lb.-ft. (501 Nm) @ 4400 RPM SAE Net
Maximum Engine Speed
Chevrolet Silverado: 6000 RPM
GMC Sierra: 6000 RPM
Chevrolet Express: 5600 RPM
GMC Savana: 5600 RPM
Emissions controls
Catalytic converter
Three-way catalyst
Positive crankcase ventilation
Materials
Block: Cast iron
Cylinder head: Cast aluminum
Intake manifold: Composite
Exhaust manifold: Cast nodular iron
Main bearing caps: Powder metal
Crankshaft: Cast nodular iron with undercut and rolled fillets
Camshaft: Hollow steel
Connecting rods: Powder metal
Additional features
Electronic throttle control
Unique exhaust valves, intake and exhaust valve seats for CNG/LPG durability
Extended life accessory drive belt
Extended life coolant
Extended life spark plugs
Oil Life Monitor System
Variable valve timing (VVT)
GM 6.0L V8 Vortec L96 Engine Vehicle Applications
Vehicle Transmission
Chevrolet Express LPG (Cutaway) MYD-6L90
Chevrolet Express CNG (Cargo Cutaway) MYD-6L90
Chevrolet Silverado HD < 10K GVW Bi-Fuel (CNG) MYD-6L90 Chevrolet Silverado HD > 10K GVW Bi-Fuel (CNG) MYD-6L90
GMC Savana CNG (Cargo Cutaway) MYD-6L90
GMC Savana LPG (Cutaway) MYD-6L90
GMC Sierra HD > 10K GVW Bi-Fuel (CNG) MYD-6L90
GMC Sierra HD < 10K GVW Bi-Fuel (CNG) MYD-6L90
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