View Single Post
Old 08-02-2007, 01:36 AM   #12
Mr. Wyndham
I used to be Dragoneye...
Mr. Wyndham's Avatar
Drives: 2018 ZL1 1LE
Join Date: Jan 2007
Location: Buffalo, NY
Posts: 31,601
Send a message via AIM to Mr. Wyndham
I could only find info on the Truck version...but it's pretty much apples to apples:

2007 Vortec Max 6.0L V8 VVT (L76)

2007 Model Year Summary

 New 6.0L Engines for 2007 include: (RPOs L76, LY6 )
 (L76) applications are: Chevrolet Avalanche, Suburban, Silverado, and GMC Yukon XL and Sierra
 SAE Certified Power rating
 Gen IV Cylinder Block
 Variable Valve Timing
 Active Fuel Management (RPO L76)
 High-Flow Cylinder Heads
 Returnless Fuel Injection with Stainless Steel Fuel Rail
 Advanced Electronic Throttle Control
 E38 Engine Control Module
 58X Ignition System
 Enhanced Noise, Vibration and Harshness Control
 Smaller Ignition Coils
 Iridium Tip Spark Plugs

Full Description of New and Update Features

New Engine (L76) for 2007 Chevrolet Avalanche, Suburban, Silverado and GMC Yukon XL, and Sierra
The next-generation Vortec 6.0L V8 is optional in the all-new Chevrolet Avalanche, Suburban and GMC Yukon XL full-size sport-utility vehicles and New Silverado and Sierra pickups. In all applications the Vortec 6.0L is installed with GM Powertrain’s high-capacity Hydra-Matic 4L70 four-speed automatic transmission.

The Vortec 6.0L is available with an aluminum (L76) cylinder block, is equipped with GM’s industry leading Active Fuel Management technology. The 6.0L also features industry first cam-in-block variable valve timing.
These engines are the 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 Vortecs 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.

Gen IV Cylinder Block
The Gen IV cylinder block shares two key design elements with GM’s original small block V8: a 90-degree cylinder angle with 4.4 inch bore centers. Beyond that, the latest small block applies design, casting and machining technologies that were unfathomable in the 1950s.

The Gen IV block debuted in 2005 as the foundation for the 400-hp LS2 V8 in the Chevrolet Corvette, Cadillac CTS-v and Pontiac GTO. The new Vortec truck block applies all the improvements in the LS2, tailored for the demands of truck application.
Developed with the latest math-based tools and data acquired in GM’s racing programs, the new block provides an exceptionally light, rigid foundation for an impressively smooth engine. Its deep-skirt design helps maximize strength and minimize vibration. The bulkheads accommodate six-bolt, cross-threaded main-bearing caps that limit crank flex and stiffen the engine’s structure. A structural oil pan further stiffens the powertrain.

The new-generation small block is cast with oil ports in its V, or valley, to accommodate advanced technologies in the Vortec 6.0L, including Active Fuel Management (AFM) cylinder deactivation (below). The Lifter Oil Manifold Assembly (LOMA), a key component of AFM, installs in the valley in place of a conventional engine block cover. As a result, knock sensors located in the valley on the Gen III V8 have been moved to the outside of the engine block, while the cam sensor has been moved from the rear of the block to the front cover.

The new Vortec 6.0L is offered with either a conventional cast-iron (LY6) or an aluminum engine block (L76), giving customers a choice and allowing technology appropriate to the application. The lighter aluminum block allows vehicle engineers more latitude in tailoring weight distribution, and can mean a slight improvement in fuel economy. The Gen IV aluminum block is cast from A356-T6 alloy, with pressed-in iron cylinder liners. It weighs roughly 100 lbs. less than a comparable cast-iron engine block.

Variable Valve Timing
The Gen IV Vortec 6.0Ls bring GM Powertrain’s industry exclusive cam-in-block variable valve timing (VVT), or cam phasing, to the small block V8. VVT eliminates the compromise inherent in conventional fixed valve timing and allows a previously unattainable mix of low-rpm torque, even torque delivery over a broad range of engines speeds, and free-breathing high-rev horsepower. The cam-phasing system in the Vortec 6.0Ls is similar in concept to that introduced in GM’s 3.9L and 3.5L V6 car engines for 2006.

The Vortec 6.0L’s dual-equal cam phaser adjusts camshaft timing at the same rate for both intake and exhaust valves. A vane-type phaser is installed on the cam sprocket to turn the camshaft relative to the sprocket, thereby adjusting the timing of both intake and exhaust valve operation. The vain phaser is actuated by hydraulic pressure from engine oil, and managed by a solenoid that controls oil pressure on the phaser. The phaser uses a wheel or rotor with four vanes (like a propeller) to turn the camshaft relative to the cam sprocket, which turns at a fixed rate via chain from the crankshaft. The solenoid directs oil to pressure points on either side of the four phaser vanes; the vanes, and camshaft, turn in the direction of the oil flow. The more pressure, the more the phaser and camshaft turn. The Vortec 6.0L’s new E38 engine control module (below) directs the phaser to advance or retard cam timing, depending on driving demands. The dual-equal phaser can turn the camshaft over a range of 31 degrees relative to the cam sprocket (or 17 degrees advance, 45 degrees retard relative to the crank).

The benefits are considerable. The cam phaser changes valve timing on the fly, maximizing engine performance for given demands and conditions. At idle, for example, the cam is at the full advanced position. That allows exceptionally smooth idling. Under other operating demands, the phaser adjusts to deliver optimal valve timing for performance, drivability and fuel economy. At high rpm it might retard timing to maximize airflow through the engine and increase horsepower. At low rpm it advances timing to increase torque. Under a light load (say, casual everyday driving), it can retard timing at all engine speeds to improve fuel economy. Without cam phasing, a cam design must be biased toward one strength or another—high-end horsepower or low-end torque, for example—or profiled at some median level that maximizes neither.

Variable valve timing allows linear delivery of torque, with near-peak levels over a broad rpm range, and high specific output (horsepower per liter of displacement) without sacrificing overall engine response, or drivability. It also provides another effective tool for controlling exhaust emissions. Because it manages valve overlap at optimum levels, it eliminates the need for an Exhaust Gas Recirculation (EGR) system.

Finally, cam-phasing helps maximize the fuel-saving benefits of Active Fuel Management technology (below). The cam phaser can adjust valve-timing for maximum torque when the Vortec 6.0L is operating as a V4, keeping the engine in this fuel-saving mode as long as possible.

Active Fuel Management (RPO L76)
Aluminum-block Gen IV Vortec 6.0Ls feature GM’s Active Fuel Management technology (AFM). AFM temporarily de-actives four of the 6.0L’s cylinders under light load conditions. It should increases fuel economy some 7 percent under the federal government’s required testing procedure and potentially more in certain real-world driving conditions. Yet truck owners don’t have to compromise on the Vortec 6.0Ls outstanding peak horsepower to go farther on a tank of gas.

Active Fuel Management stems from a simple premise: most truck owners have more power than they need much of the time. Many choose powerful V8 engines to be prepared for the occasional heavy load, but during routine commuting that powerful engine operates at a fraction of its capability. Volumetric efficiency is impaired, and that means less than optimal fuel mileage. AFM offers a common-sense solution. It saves fuel by using only half of the Vortec 6.0L’s cylinders during some driving conditions, and seamlessly reactivates the other cylinders when a driver demands full power for acceleration or load hauling.

Managed by the new 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 (below) 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 Vortec 6.0L, 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 Vortec 6.0’s V, or valley, 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 Gen IV Vortec 6.0L’s fuel injectors 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 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.

High-Flow Cylinder Heads
The Gen IV Vortec 6.0Ls are fitted with high-flow cylinder heads, based on those developed for the high-performance LS2 and LS6 car V8s. These heads have offset rockers, like those in the LS7. They also have larger valves than other Vortec V8 heads, and increase airflow in and out of the engine for higher horsepower. Yet the Vortec 6.0 heads maintain a compression ratio that allows these engines to operate on regular gas.

Returnless Fuel Injection with Stainless Steel Fuel Rail
The Vortec 6.0L is equipped with a "returnless’’ fuel injection system, also known as a demand system, and the latest-generation Multec injectors with USCAR connectors. The Gen IV V8s represents one of GM’s first applications of USCAR-standard electrical connectors for the fuel injectors. The standard was developed to promote common, reliable connections across the auto industry and streamline regulatory oversight. The connectors are more compact than previous connectors, and designed for improved sealing.

Recently introduced on the Gen III Vortec V8s, returnless fuel injection represents a paradigm shift for GM, developed to improve performance and decrease evaporative emissions. Previously, Vortec 6.0Ls used a return line between the engine and the fuel tank to manage fuel pressure by bleeding off excess fuel at the fuel rail and returning the excess to the tank. The new system eliminates the return lines and moves the fuel pressure regulator from the fuel rail on the engine to the fuel tank. Because it delivers only the amount of fuel needed by the injectors, and returns no fuel to the gas tank, the returnless system essentially eliminates heat transfer from the engine to tank. This reduces the amount of vapor generated in the tank and captured by the vehicle’s Onboard Refueling Vapor Recovery (ORVR) system.

With the returnless system, the 6.0L uses a fuel rail manufactured of stainless steel. Previous versions use a nylon rail. The stainless steel rail allows installation of baffles that manage fuel pulses in the returnless system and reduce noise.
Attached Images
"Keep the faith." - Fbodfather
Mr. Wyndham is offline   Reply With Quote