99-LS1-SS
10-23-2008, 06:01 AM
2008 “L76” 6.0L V8 (L76)
6.0L Gen IV V8 (L76) CAR ENGINE
2008 Model Year Summary
• Active Fuel Management Calibrated For Pontiac G8 GT Passenger Car
• Structural Cast Aluminum Oil Pan Specific To G8
• Intake Manifold From LS3 Corvette Application
• Induction System Specific To G8
• Exhaust Manifolds Design Specific To G8
• Electronic Throttle Control From LS3 V8 Application
• Gen IV Cast Aluminum Cylinder Block
• High-Flow Cylinder Heads
• Returnless Fuel Injection with Stainless Steel Fuel Rail
• Advanced Electronic Throttle Control Similar To LS3 V8
• E38 Engine Control Module
• 58X Ignition System
• Enhanced Noise, Vibration and Harshness Control
• Smaller Ignition Coils From LS3 V8
• Iridium Tip Spark Plugs
6.0L V8 (L76)
The 6.0L (L76) V8 is a cast aluminum block V8 with GM’s industry leading Active Fuel Management (AFM) technology. For 2008, the Vortec 6.0L V8 VVT (L76) is found in the Chevrolet Avalanche, Silverado and Suburban, and the GMC Sierra and Yukon XL models with an industry first cam-in-block variable valve timing (VVT) system. The Pontiac G8 is the first passenger car application for the L76, but without VVT.
This engine is from the family of fourth-generation descendents of one of the most important and successful engines in automotive history—the original Chevrolet small-block, which debuted in 1955. The Gen IV V8’s feature technology creators of the first small block could not have imagined, yet they share one fundamental trait with the original: a market-leading balance of performance, sophistication, economy and durability.
The Small Block Vortec V8s have fueled GM’s leadership in truck sales because they provide the right technology for the job, and now this technology is expanded to rear-drive high-performance passenger cars with the 6.0L (L76).
Full Description of New And Updated Features
Active Fuel Management Calibrated For Pontiac G8 GT Passenger Car
The aluminum-block Gen IV 6.0L (L76) features GM’s Active Fuel Management technology (AFM). AFM temporarily de-activates four of the 6.0L’s cylinders under light to moderate load conditions. It should increase fuel economy approximately 6 percent under the federal government’s required testing procedure and potentially more in certain real-world driving conditions. Yet V8-powered rear-drive performance vehicles don’t have to compromise on the outstanding peak horsepower of the 6.0L (L76) to go farther on a tank of gas.
Active Fuel Management stems from a simple premise: most V8 cars have more power than owners demand in all conditions. With AFM, owners have a choice to save fuel during routine commuting. The 6.0L (L76) saves fuel by using only half of the 6.0L’s cylinders during some driving conditions, and seamlessly reactivates the other cylinders when a driver demands full power for acceleration.
Managed by the sophisticated E38 engine control module (ECM), AFM automatically shuts down every second cylinder, according to firing order, during light-load operation. In engineering terms, this allows the working cylinders to achieve better thermal, volumetric and mechanical efficiency by reducing heat loss, combustion loss and friction, and lowering cyclical combustion variation from cylinder to cylinder. As a result, AFM delivers better fuel economy and lower operating costs. Perhaps the most sensible thing about AFM is that it harnesses the engine’s existing capabilities, starting with the potential designed into the E38 ECM. The only mechanical components required are special valve lifters for cylinders that are deactivated, and their control system. The incremental cost for the customer is nominal per engine. Active Fuel Management relies on three primary components: De-ac (for deactivation) or collapsible valve lifters, a Lifter Oil Manifold Assembly (LOMA), and the ECM.
One of the most sophisticated engine controllers extant, the E38 ECM measures load conditions based on inputs from vehicle sensors and interprets that information to mange more than 100 engine operations, from fuel injection to spark control to electronic throttle control. AFM adds an algorithm to the engine control software to manage cylinder deactivation and reactivation. When loads are light, the E38 automatically closes both intake and exhaust valves for half of the cylinders and cuts fuel delivery to those four. The valves re-open to activate all cylinders when the driver demands brisk acceleration or full torque to move a load. The engine’s electronic throttle control (ETC) is used to balance torque following cylinder deactivation or reactivation. The transition takes less than 20 milliseconds, and can’t be detected by the driver.
Valve lifters are operated by the engine’s camshaft, and lift a pushrod that operates the valves in the cylinder head. In the Gen IV 6.0L (L76), the De-Ac lifters are installed in cylinders 1, 4, 6 and 7, while the remaining cylinders use conventional lifters. The hydraulically operated De-Ac lifters have a spring-loaded locking pin actuated by oil pressure. For deactivation, hydraulic pressure dislodges the locking pin, collapsing the top portion of the lifter into the bottom and removing contact with the pushrod. The bottom of each De-Ac lifter rides up and down on the cam lobe but the top does not move the push rod. The valves do not operate and combustion in that cylinder stops. During reactivation, the oil pressure is removed, and the lifter locks at full length. The pushrods, and therefore the valves, operate normally.
The final AFM component is the LOMA. This cast-aluminum assembly is installed in the valley of the 6.0L (L76) in place of a conventional engine block cover. The LOMA holds four solenoids, control wiring and cast-in oil passages. The solenoids are managed by the ECM, and each one controls oil flow to a De-Ac Lifter, activating and de-activating the valves at one cylinder as required for Active Fuel Management.
The fuel injectors in the Gen IV 6.0L (L76) are identical for all cylinders; those feeding the de-activated cylinders are simply shut down electrically by the ECM during de-activation. When the cylinders are deactivated, the engine effectively operates as a V4. AFM operation is load based, as measured by the ECM using dozens of inputs, overlain with the driver’s demand for power as measured by throttle application. AFM’s response time varies with oil temperature, but in all cases is measured in milliseconds. Operation is always transparent to the driver. The engine returns to V8 mode the instant the controller determines that acceleration or load requires additional power.
The benefits are substantial. Active Fuel Management does not effect exhaust emissions, and it will reduce overall emissions significantly, including greenhouse gases such as CO2, to the extent that less fuel is used. Further, the savings reflected in EPA numbers may not account for AFM’s full impact. Owners who primarily travel long distances at steady speeds will see substantially greater fuel-economy improvements. Because of the reduced mass of the Pontiac G8 GT compared to the full-size trucks which use the majority of the Gen IV V8 engines, the calibrations for switching from a V4 powered configuration to a V8 configuration have been modified to optimize efficiency.
Continued in next post.
6.0L Gen IV V8 (L76) CAR ENGINE
2008 Model Year Summary
• Active Fuel Management Calibrated For Pontiac G8 GT Passenger Car
• Structural Cast Aluminum Oil Pan Specific To G8
• Intake Manifold From LS3 Corvette Application
• Induction System Specific To G8
• Exhaust Manifolds Design Specific To G8
• Electronic Throttle Control From LS3 V8 Application
• Gen IV Cast Aluminum Cylinder Block
• High-Flow Cylinder Heads
• Returnless Fuel Injection with Stainless Steel Fuel Rail
• Advanced Electronic Throttle Control Similar To LS3 V8
• E38 Engine Control Module
• 58X Ignition System
• Enhanced Noise, Vibration and Harshness Control
• Smaller Ignition Coils From LS3 V8
• Iridium Tip Spark Plugs
6.0L V8 (L76)
The 6.0L (L76) V8 is a cast aluminum block V8 with GM’s industry leading Active Fuel Management (AFM) technology. For 2008, the Vortec 6.0L V8 VVT (L76) is found in the Chevrolet Avalanche, Silverado and Suburban, and the GMC Sierra and Yukon XL models with an industry first cam-in-block variable valve timing (VVT) system. The Pontiac G8 is the first passenger car application for the L76, but without VVT.
This engine is from the family of fourth-generation descendents of one of the most important and successful engines in automotive history—the original Chevrolet small-block, which debuted in 1955. The Gen IV V8’s feature technology creators of the first small block could not have imagined, yet they share one fundamental trait with the original: a market-leading balance of performance, sophistication, economy and durability.
The Small Block Vortec V8s have fueled GM’s leadership in truck sales because they provide the right technology for the job, and now this technology is expanded to rear-drive high-performance passenger cars with the 6.0L (L76).
Full Description of New And Updated Features
Active Fuel Management Calibrated For Pontiac G8 GT Passenger Car
The aluminum-block Gen IV 6.0L (L76) features GM’s Active Fuel Management technology (AFM). AFM temporarily de-activates four of the 6.0L’s cylinders under light to moderate load conditions. It should increase fuel economy approximately 6 percent under the federal government’s required testing procedure and potentially more in certain real-world driving conditions. Yet V8-powered rear-drive performance vehicles don’t have to compromise on the outstanding peak horsepower of the 6.0L (L76) to go farther on a tank of gas.
Active Fuel Management stems from a simple premise: most V8 cars have more power than owners demand in all conditions. With AFM, owners have a choice to save fuel during routine commuting. The 6.0L (L76) saves fuel by using only half of the 6.0L’s cylinders during some driving conditions, and seamlessly reactivates the other cylinders when a driver demands full power for acceleration.
Managed by the sophisticated E38 engine control module (ECM), AFM automatically shuts down every second cylinder, according to firing order, during light-load operation. In engineering terms, this allows the working cylinders to achieve better thermal, volumetric and mechanical efficiency by reducing heat loss, combustion loss and friction, and lowering cyclical combustion variation from cylinder to cylinder. As a result, AFM delivers better fuel economy and lower operating costs. Perhaps the most sensible thing about AFM is that it harnesses the engine’s existing capabilities, starting with the potential designed into the E38 ECM. The only mechanical components required are special valve lifters for cylinders that are deactivated, and their control system. The incremental cost for the customer is nominal per engine. Active Fuel Management relies on three primary components: De-ac (for deactivation) or collapsible valve lifters, a Lifter Oil Manifold Assembly (LOMA), and the ECM.
One of the most sophisticated engine controllers extant, the E38 ECM measures load conditions based on inputs from vehicle sensors and interprets that information to mange more than 100 engine operations, from fuel injection to spark control to electronic throttle control. AFM adds an algorithm to the engine control software to manage cylinder deactivation and reactivation. When loads are light, the E38 automatically closes both intake and exhaust valves for half of the cylinders and cuts fuel delivery to those four. The valves re-open to activate all cylinders when the driver demands brisk acceleration or full torque to move a load. The engine’s electronic throttle control (ETC) is used to balance torque following cylinder deactivation or reactivation. The transition takes less than 20 milliseconds, and can’t be detected by the driver.
Valve lifters are operated by the engine’s camshaft, and lift a pushrod that operates the valves in the cylinder head. In the Gen IV 6.0L (L76), the De-Ac lifters are installed in cylinders 1, 4, 6 and 7, while the remaining cylinders use conventional lifters. The hydraulically operated De-Ac lifters have a spring-loaded locking pin actuated by oil pressure. For deactivation, hydraulic pressure dislodges the locking pin, collapsing the top portion of the lifter into the bottom and removing contact with the pushrod. The bottom of each De-Ac lifter rides up and down on the cam lobe but the top does not move the push rod. The valves do not operate and combustion in that cylinder stops. During reactivation, the oil pressure is removed, and the lifter locks at full length. The pushrods, and therefore the valves, operate normally.
The final AFM component is the LOMA. This cast-aluminum assembly is installed in the valley of the 6.0L (L76) in place of a conventional engine block cover. The LOMA holds four solenoids, control wiring and cast-in oil passages. The solenoids are managed by the ECM, and each one controls oil flow to a De-Ac Lifter, activating and de-activating the valves at one cylinder as required for Active Fuel Management.
The fuel injectors in the Gen IV 6.0L (L76) are identical for all cylinders; those feeding the de-activated cylinders are simply shut down electrically by the ECM during de-activation. When the cylinders are deactivated, the engine effectively operates as a V4. AFM operation is load based, as measured by the ECM using dozens of inputs, overlain with the driver’s demand for power as measured by throttle application. AFM’s response time varies with oil temperature, but in all cases is measured in milliseconds. Operation is always transparent to the driver. The engine returns to V8 mode the instant the controller determines that acceleration or load requires additional power.
The benefits are substantial. Active Fuel Management does not effect exhaust emissions, and it will reduce overall emissions significantly, including greenhouse gases such as CO2, to the extent that less fuel is used. Further, the savings reflected in EPA numbers may not account for AFM’s full impact. Owners who primarily travel long distances at steady speeds will see substantially greater fuel-economy improvements. Because of the reduced mass of the Pontiac G8 GT compared to the full-size trucks which use the majority of the Gen IV V8 engines, the calibrations for switching from a V4 powered configuration to a V8 configuration have been modified to optimize efficiency.
Continued in next post.