2008 GM 3.9L V6 (LGD, LZ9, LZ8) 3.9L V6 ( LGD, LZ9, LZG ) CAR AND TRUCK ENGINE 2008 Model Year Summary 1 2 3 New RPO for 2008 Chevrolet Impala (LZG) E85 Flexible-Fuel Capability with Active Fuel Management (LZG) E85 Flexible-Fuel Capability (LGD) Full Description of New and Update Features New RPO for the 2008 Chevrolet Impala (LZG) GM Powertrain’s new-generation 60-degree 3.9L V6 is now available with Active Fuel Management cylinder-deactivation technology combined with E85 flex-fuel capability and Variable Valve Timing (LZG). RPO LZG is optional in Impala. RPO (LGD) is optional in Chevrolet Uplander and Pontiac Montana SV6 and features Variable Valve Timing and E85 flex-fuel capability. RPO (LZ9) also with Variable Valve Timing, is offered for 2008 in the Pontiac G6, Pontiac Montana SV6, and Chevrolet Uplander. In all applications, the 3.9L V6 is installed with GM Powertrain’s Hydra-Matic 4T65 four-speed automatic transmission. Active Fuel Management (LZG) The 3.9L is the first GM V6 in North America equipped with GM’s industry exclusive Active Fuel Management (AFM) technology. (GM has a 3.0L V6 with AFM in China in the Buick LaCrosse. It is similar in concept and execution to AFM introduced on the Gen IV small-block V8s, tuned specifically for a six-cylinder engine. Active Fuel Management temporarily de-activates three of the 3.9L’s cylinders under light load conditions. It should increases fuel economy measurably under the federal government’s required testing procedure, and potentially more in certain real-world driving conditions. Yet vehicle owners don’t have to compromise on the 3.9Ls outstanding balance of power and torque to go farther on a tank of gas. AFM stems from a simple premise: many drivers have more power than they need much of the time. Many choose powerful engines for their potential for exhilarating acceleration, or good performance at full load. Yet 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 3.9Ls cylinders during some driving conditions, and seamlessly reactivates the other cylinders when a driver demands full power for acceleration. 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, 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 three. The valves re-open to activate all cylinders when the driver demands brisk acceleration or full torque. 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 3.9L, the De-ac lifters are installed in cylinders 1, 3, and 5, 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 3.9L’s V, or valley, in place of a conventional engine block cover. The LOMA holds three 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 3.9L V6’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 with three cylinders. 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 V6 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. Active Fuel Management required fine-tuning for the 3.9L V6 to maintain excellent noise and vibration control in both three and six-cylinder mode. Because AFM activates and de-activates cylinders according to firing order, it works on cylinders in the 3.9L’s left bank. In fuel-saving mode, the 3.9L effectively operates as an inline 3. This creates more slack in the accessory drive belt. The alternator is therefore equipped with a unique de-coupling clutch that seamlessly tensions the belt as the engine switches between modes. And because the engine generates different exhaust-pulse frequencies in three- and six-cylinder modes, the exhaust system is tuned for the same smooth, quiet operation in both. , The 3.9L’s exclusive cam-in-block VVT technology works synergistically with Active Fuel Management and helps maximize AFM’s fuel saving potential. The cam phaser can adjust valve-timing for maximum torque when the 3.9L is operating as a three-cylinder, keeping the engine in this fuel-saving mode as long as possible. E85 Flexible-Fuel Capability (LGD, LZG) GM has led the industry in introducing flex-fuel capability to its cars and trucks, and the flex-fuel capable 3.9L V6 (RPO’s LGD and LZG) extends availability to an even broader range of customers. E85 is a clean-burning alternative fuel made in the United States from corn and other crops, composed of 85 percent ethanol alcohol and 15 percent gasoline. The 3.9L’s flex-fuel technology is both sophisticated and durable. The first flex-fuel engines required special valves and valve seats to withstand the corrosive effects of ethanol. Not the 3.9L V6. The Silcrome 1 valves used in all variants are up to the challenge. Compared to conventional iron-alloy valve material, Silcrome 1 includes tungsten, vanadium, manganese, silicone and higher chromium content. It is harder, and it improves durability, even under the rigors of ethanol operation. Hardware changes for flex-fuel operation are limited to the injectors. Because ethanol has fewer BTUs (less energy) than the same volume of gasoline, more fuel is required to produce the same horsepower at wide-open throttle. Flex fuel engines use unique injectors with a diamond-like finish, greater cone angle and higher maximum fuel-flow rate. The fuel rail matches the injectors, but it’s manufactured of the same stainless steel used for all 3.9L V6 fuel rails. The flex-fuel 3.9L doesn’t require a special fuel sensor. The first flex-fuel engines used a light-reactive sensor to measure fuel composition from 100 percent gasoline to 85 percent ethanol. The 3.9L has a virtual sensor—software programmed in the E38 ECM with no separate physical sensor whatsoever. Based on readings from the oxygen (O²) sensors, fuel level sensor and vehicle speed sensors, the ECM adjusts the length of time the fuel injectors open for the type of fuel used. Within a few miles after filling up, the E38 controller determines what fuel is powering the 3.9L V6 and manages the engine accordingly. E85 fuel provides an environmentally friendly companion or alternative to gasoline. It is biodegradable and doesn’t contaminate the water supply. Ethanol can be produced from various feed stocks, including corn and wheat stalks, forestry and agricultural waste, and even municipal waste. Advanced Engine Control Modules Every 3.9L V6 is managed by one of the three controllers in GM Powertrain’s new family of engine control modules (ECM), which will direct nearly all engines in Powertrain’s line-up. These ECMs more precisely orchestrate the myriad operations that occur within the 3.9L every split second. In combination with advanced sensor technology, they include the ability to control and synchronize systems such as Active Fuel Management and cam-in-block variable valve timing. Most 3.9Ls use the mid-line controller, know as the E38. The 3.9Ls built for the Buick Terazza, Chevrolet Uplander, Pontiac Montana SV6 and Saturn Relay are equipped with the high-line E67 ECM. These ECMs feature 32-bit processing, compared to the conventional 16-bit processing in previous 60-degree V6 engines. They operate at 59 MHz, with 32 megabytes of flash memory, 128 kilobytes of RAM and a high-speed CAN bus, and the synchronizes more than 100 functions, from spark timing to cruise control operation to traction control calculations. The E38 works roughly 50 times faster than the first computers used on internal combustion engines in the late 1970s, which managed five or six functions. The family strategy behind GM’s new ECMs allows engineers to apply standard manufacturing and service procedures to all powertrains, and quickly upgrade certain engine technologies while leaving others alone. It creates both assembly and procurement efficiencies, as well as volume sourcing. In short, it creates a solid, flexible, efficient engine-control foundation, allowing engineers to focus on innovations and get them to market more quickly. The family of controllers means the ECM and corresponding connectors can be packaged and mounted identically in virtually every GM vehicle. Powertrain creates all the software for the three ECMs, which share a common language and hardware interface that’s tailored to each vehicle. The new ECMs also apply a new, rate-based monitoring protocol sometimes known as run-at-rate diagnostics. Rate-based diagnostics improve the robustness of the Onboard Diagnostics System (OBD II) and ensure optimal performance of emissions control systems. The new software increases the frequency at which the ECM checks various 3.9L systems, and particularly emissions-control systems such as the catalytic converter and oxygen sensors. Rate-based diagnostics more reliably monitor real-word operation of these systems, and allow regulatory agencies to more easily measure and certify emissions compliance. Overview GM Powertrain’s new overhead-valve V6 engines demonstrate conclusively that the inherent strengths of cam-in-block design can be applied in the environmentally sensitive 21st century--in trucks and cars. With advanced technologies such as Active Fuel Management and variable vale timing, the 3.9L delivers the power and flexibility of a large-displacement V6 with new levels of fuel efficiency. It brings innovation to the mainstream, with wide application in a high-value package the typical consumer can afford. This new generation V6 allows a high level of flexibility, with common castings over a range of displacements. The 3.9L V6 shares its block, pistons and cylinder heads with Powertrain’s new 3.5L (RPOs LZ4 and LZE). A common bore measures 99 mm; displacement is increased in the 3.9L with a longer stroke (84 mm, compared to 76 mm for the 3.5L). The two engines share 80 percent of their parts. Thanks to its relatively narrow 60-degree block angle, the 3.9L V6 is compact, giving vehicles teams more latitude with platform design and styling. More importantly, the 60-degree configuration is inherently balanced, ensuring powertrain smoothness without the additional cost of balance shafts. The new 3.9L V6 differs from previous GM 60-degree designs in its offset cylinder bores. The centerlines through the bores on each bank do not intersect at the crank axis; rather, they intersect 3 mm below the crank axis. The offset bores present a number of advantages, including room for larger cam journals and flexibility to stroke the engine for more displacement. The 3.9L block also features a unique “U-flow” coolant path. The coolant passages flow coolant in a specific, predetermined path, starting at the front of block, then rearward toward transmission, up through the cylinder heads and back to the front. The thermostat is placed near the inlet from the radiator, decreasing warm-up time. The fill point is at the highest point of the cooling system to prevent air pockets in the hoses or passages. The cylinder heads apply design features developed for the high-output LS1 and LS6 Corvette small-block V8s. The 3.9L V6’s valves are similar to those in the LS1, as is its combustion chamber design. Low-friction hydraulic roller lifters work the valves, improving the engine’s efficiency and reducing vibration. Before introduction of the 3.9LV6, variable intake manifolds were not a familiar feature on overhead-valve V6 engines, The 3.9L V6’s two-piece cast aluminum manifold has a valve in its plenum to optimize air intake for the desired performance parameters, eliminating the compromise required with a fixed-flow intake manifold. At low engine speeds, the engine control module (ECM) closes the valve to create a longer intake path, improving combustion efficiency and increasing torque. At higher engine speeds, it opens the valve, shortening the path for free breathing and maximum horsepower. The 3.9L also applies the latest electronic throttle control (ETC) technology, streamlining the system by eliminating a separate throttle actuator control (TAC) module. The ECM controls the throttle motor directly. The direct link improves throttle response time (albeit in millisecond increments that are not apparent to the driver) and improves system security by removing a device (the TAC) the must be monitored for malfunction. The 3.9L V6’s “returnless” fuel injection system is the new standard at GM. It eliminates fuel return lines between the engine and the gasoline tank, essentially eliminating heat transfer from the engine to the tank and reducing the amount of vapor emissions substantially. New generation fuel injectors with shrouded nozzles are designed to minimize clogging and maintain optimal performance when in high heat. For all the advanced systems in the 3.9L V6, perhaps the most significant—certainly the one that has garnered the most attention—is variable valve timing (VVT). GM’s new generation V6s were the first cam-in-block engines with VVT—an accomplishment engineers considered extremely difficult, if not impossible, just a few years ago. The 3.9L’s dual-equal VVT uses a hydraulically operated vane-type cam phaser that turns the camshaft relative to its drive sprocket. The advantages of cam-in-block VVT are pronounced. 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. Virtually every component and system in GM’s new generation cam-in-block V6s was reviewed in an effort to enhance durability and reduce noise, vibration and harshness. Piston-cooling jets remain the exception rather than the rule in overhead cam engines, yet each piston in the 3.9L V6 has its own pressure-actuated jet that sprays oil toward its skirt, coating its underside and the cylinder wall with an additional layer of lubricant. The extra lubrication cools the pistons, reducing both friction and operational noise and helping ensure durability. The cam-drive chain has a leaf spring-type dampener that maintains optimal chain tension for the life of the engine and eliminates any flapping motion that might develop as the chain stretches with mileage. It ensures that the timing chain operates as smoothly and quietly as new, even as the engine accumulates high mileage. Multi-layer steel gaskets are sandwiched between the block and cylinder heads to maintain optimal sealing for the life of the engine. The cast-iron exhaust manifolds are fitted with heat shields fabricated from stainless steel and insulating material. These limit heat transfer from the engine to the engine bay, allowing the 3.9L to reach optimal operating temperature more quickly, yet reducing heat in the engine compartment once that temperature is achieved. They also dampen the sound of exhaust gas rushing through the manifolds and further reduce the amount of engine operational noise that finds its way into the vehicle interior. A cast aluminum oil pan increases engine rigidity and radiates less noise than a conventional steel pan. An acoustic engine cover further reduces the amount of noise transmitted to the passenger compartment from the engine. Low maintenance was a development priority. The spark plugs have an iridium tip and core to maintain spark density over their 100,000-mile life, helping ensure the same fuel efficiency and emissions performance over the last 10,000 miles as the first. The coolant and accessory belt are both expected to last 100,000 miles. Maintenance in typical use is limited to oil changes, and even those are made as simple as possible. The GM Oil Life System measures how hard the engine is used and calculates the optimal life expectancy of the engine oil, indicating an oil change when it’s actually needed, rather than according to some predetermined mileage interval. GM’s new overhead-valve V6 engines define the concept of high value in powertrain development. The deliver advanced, industry exclusive technologies with real benefit for customers, yet they keep both the cost of production and the cost of ownership low. In short, the new 3.9L V6 delivers a top-shelf balance of good specific output, low-end response, even torque delivery, low maintenance and value, with vehicle packaging flexibility in a wide range of front and all-wheel drive applications.