Vortec 4200 4.2L I-6 (LL8)
2005 Model Year Summary
· Application in 2005 Saab 9-7X
· Improved cam phaser
· Returnless fuel injection
· Improved compression rings
· Improved intake manifold and throttle body gaskets
· Improved ORVR purge valve
· Vented starter solenoid
· Improved throttle mapping
· NVH enhancements
· GF-4 engine oil
FULL DESCRIPTIONS OF NEW OR CHANGED FEATURES
APPLICATION IN SAAB 9-7X
GM Powertrain’s 4.2L inline six-cylinder (RPO LL8) will power Saab’s first sport-utility vehicle, the 2005 Saab 9-7X. LL8’s built for this application are identical to those powering GM’s mid-size SUVs. The Saab 9-7X was designed to be capable of higher lateral and braking g loads and a higher top speed than the typical SUV, potentially creating additional demands on the engine’s lubrication and cooling system. The LL8 was validated for these higher demands with no modifications.
IMPROVED CAM PHASER
The Vortec 4200 is now equipped with a vane-type cam phaser, replacing the helical spline and piston phaser used since the engine’s launch. The vane phaser represents the current state-of-the-art in cam phaser and it delivers several benefits.
The Vortec 4200 was one of the world’s first truck engines with variable valve timing, or cam phasing. The cam phaser changes exhaust cam lobe timing relative to the cam-drive sprocket, which in turn varies exhaust valve timing on the fly, maximizing engine performance for given demands and conditions. At idle, for example, the exhaust cam is at the full advanced position for minimum intake-valve overlap. That allows exceptionally smooth idling. Under other operating demands, the phaser adjusts to deliver optimal exhaust-valve timing for performance, drivability and fuel economy. The result is 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. Because it manages valve overlap at optimum levels, cam phasing also eliminates the need for an Exhaust Gas Recirculation (EGR) system.
As it was with the spline-piston phaser, the new vane phaser is actuated by hydraulic pressure from engine oil, and managed by a solenoid that is set to a specified duty-cycle and controls oil pressure on the phaser. Yet the operating mechanism is different. Instead of helical spline and piston, the vane phaser uses a wheel with four vanes (like a propeller) to turn the camshaft relative to the cam-sprocket. The solenoid directs oil to pressure points on either side of the four vanes; the vanes, and camshaft, turn in the direction of the oil flow. The more pressure, the more the phaser and camshaft turn. Like the previous phaser, the vane phaser turns the Vortec 4200’s camshaft a maximum 24 degrees relative to the sprocket.
The vane phaser is a much simpler device than the spline-piston phaser, with fewer parts. The vane wheel is made of extruded aluminum; it requires less machining and it’s less expensive to manufacture. Moreover, the vane phaser is more robust. It’s validated to ten years or 150,000 miles of operation. It is less sensitive to disruption from excessive debris in the oil.
Most important, the vane phaser performs more quickly and efficiently than the spline-piston phaser. Because it generates less friction, in turns the camshaft faster—in some conditions, as when the engine is warm and operating at low rpm, nearly four times faster. This improved response time will be transparent to the driver, but it improves the Vortec 4200’s overall efficiency and reduces compromises when balancing performance, drivability, fuel efficiency and emissions reduction. More precise control gives engineers more options in calibrating the cam phaser to maximize its benefits.
RETURNLESS FUEL INJECTION
All Vortec 4200s are equipped with a new "returnless" fuel injection system that eliminates fuel return lines between the engine and the gasoline tank. The new fuel system is also known as a demand system.
Before model year 2005, the Vortec 4200’s Sequential Fuel Injection (SFI) used a return line to manage fuel pressure by bleeding off excess fuel at the fuel rail and returning the excess to the fuel 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. But because the returnless system delivers only the amount of fuel needed by the injectors, and returns no fuel to the fuel tank, it eliminates heat transfer from the engine to the fuel tank. This reduces the amount of vapor generated in the tank, and captured by the evaporative emissions control system, or Onboard Refueling Vapor Recovery (ORVR).
In concert with improved intake manifold and throttle body gaskets (below), returnless fuel injection allows the Vortec 4200 to meet near-zero evaporative emissions standards mandated by the Environmental Protection Agency and California Air Resources Board for implementation in 2007.
IMPROVED COMPRESSION RINGS
The Vortec 4200's second piston ring has been redesigned. This new, improved Napier-type compression ring increases in thickness from 1.2 to 1.5 mm, and it has a step in its edge. The new compression ring is more durable and ensures consistent performance over the engine's life. It also improves oil consumption at higher mileage.
IMPROVED INTAKE MANIFOLD AND THROTTLE BODY GASKETS
The Vortec 4200 has new intake manifold sealing gaskets manufactured from a fluorocarbon material.. They are common with those used on the Vortec 3500 and Vortec 2800 inline engine, increasing assembly plant efficiency.
IMPROVED ORVR PURGE VALVE
Improvements to the Vortec 4200’s evaporative emissions system (ORVR) include a new purge valve. The purge valve empties the collection canister into the engine’s intake stream. The new valve also operates more quietly.
VENTED STARTER SOLENOID
The Vortec 4200 is fitted with a new vented starter solenoid. The solenoid case has a micromesh-covered vent that protects the solenoid from debris particles but prevents moisture buildup. When the engine is warm, any moisture on the solenoid evaporates through the vent.
IMPROVED THROTTLE MAPPING
The Vortec 4200’s Electronic Throttle Control (ETC) system is programmed with a new throttle progression intended to deliver more immediate engine response at part throttle.
The Vortec 4200 was one of the first truck engines with electronic “drive-by-wire” throttle. There is no mechanical link between the accelerator pedal and the throttle. A potentiometer at the pedal measures pedal angle and sends a signal to the Powertrain Control Module (PCM); the PCM – via the Throttle Actuator Control (TAC) module – then directs an electric motor to open the throttle at the appropriate rate and angle. Besides the accelerator pedal’s angle, the PCM measures other data, including the transmission’s shift patterns and traction at the drive wheels, in determining how far to open the throttle.
The refinements in the throttle mapping focus on part-throttle application. At full throttle the Vortec 4200’s performance does not change. Yet at part throttle, the response is more immediate to the driver. With a 25-percent application of the gas pedal, for example, the throttle might open 10 percent farther than it did with the previous map, and the vehicle will accelerate more quickly.
NVH ENHANCEMENTS
The Vortec 4200 gets several subtle improvements that make one of the smoothest, quietest six-cylinder truck engines in production even quieter. These include a new, denser insulating pad on the engine side of the dashboard and thicker downpipe that reduces the transmission of exhaust noise. The stainless steel down pipe connects the exhaust manifold with the catalytic converter.
GF-4 ENGINE OIL
All Vortec 4200s will be shipped to the customers with new engine oil that reduces engine deposits, extends oil change intervals, improves fuel economy and improves the life of emissions control systems. GM Powertrain has taken a leading role in developing and introducing the new oil, designated GF-4 (for “Gasoline Fueled, Standard 4’’) by the American Petroleum Institute.
This new oil improves fuel economy by lowering engine friction. It uses an ash-free anti-oxidant that prolongs the life of the emissions control system and it also resists oil breakdown caused by high-temperature oxidation. 5W30 oil is recommended for low friction and good cold-weather starts.
OVERVIEW
Start with a fundamentally sound design philosophy; add the best technology available, exclusive durability-enhancing features and a segment-leading balance of performance and efficiency. Then start re-examining everything immediately after a successful launch.
Rave reviews in virtually every automotive media outlet, and awards, including three consecutive appearances on Ward's Auto World's 10 Best Engines list and a key role in earning the GMC Envoy Motor Trend ‘s 2002 SUV of the Year.
The Vortec 4200 4.2L I6 (LL8) was introduced in the 2002 GM mid-size SUVs, including the Chevrolet Trailblazer and GMC Envoy, and was the first inline six-cylinder engine in GM Powertrain’s lineup in nearly 20 years. While the industry largely had turned away from the inline six, GM recognized that, given careful design and development, the inherent advantages of inline six-cylinder architecture were perfect for the new millennium. Yet with the technical sophistication of premium passenger car engines and the power of competitors’ V8s, the Vortec 4200 is no ordinary line six. Its flexible architecture builds the foundation for a range of inline engines, maximizing the return on corporate investment while exceeding customers’ performance expectations.
An exceptionally light, rigid engine block and cylinder head combination, cast with the GM's patented lost foam process, provide the foundation for the Vortec 4200’s success. All-aluminum construction means less weight than conventional cast-iron truck engines, and less weight means improved fuel economy. The bottom end of the engine derives strength through many features, starting with a bearing beam, or ladder, that connects the seven main bearing caps to further stiffen the engine’s structure. The oil pan bolts to the transmission bell housing as well as the engine block, eliminating points of vibration and making the complete engine more like a single casting. The oil pan also gives “pan-axle” all-wheel-drive capability to trucks equipped with the Vortec 4200. A passage cast through the width of the oil pan allows a drive axle to pass through it rather than under it, allowing the engine to be placed lower in the vehicle for a more compact package that improves the vehicle’s handling dynamics and gives designers greater styling flexibility.
The Vortec 4200's feature list reads like those for premium luxury/performance car engines: dual-overhead cam cylinder head, four valves per cylinder, roller-follower valve actuation and exhaust-cam phasing; a 10:1 compression ratio that delivers the seemingly incompatible benefits of high compression and regular-grade fuel; Electronic Throttle Control (ETC); direct accessory mounting.
Moreover, the Vortec 4200 development team hasn’t rested on its laurels. During the three years since the engine’s launch, virtually every system and technology, from emissions control to engine management to sealing, has been examined and refined. In 2003, the Vortec 4200 was fitted with polymer coated pistons that reduce engine noise and enhance durability. The oil-pump was refined to limit noise; and the cam-chain tensioner was improved for quieter operation. For model year 2004, the Vortec 4200 was introduced in the all-new Buick Rainier and Isuzu Ascender. For ’05 it powers Saab’s first sport-utility vehicle.
Vehicle platform teams recognize the Vortec 4200’s strengths, yet its design advantages and premium features mean little if the finished product doesn’t deliver what customers demand. Customers demand low maintenance, and with Vortec 4200, oil changes are the only scheduled maintenance during the first 100,000 miles of operation, and even those are as stress-free as possible. GM’s Oil Life System (GMOLS) advises an oil change when it’s actually needed, based on real-world vehicle operation, rather than a predetermined mileage interval. The oil filter is easily accessible from underneath Vortec 4200-equipped vehicles and is mounted pointing straight down, reducing the potential for spilling oil during removal.
Most of all, customers demand performance, and the Vortec 4200 delivers more peak horsepower and comparable torque (275 hp, 275 lb-ft) to competitors’ larger-displacement V-8s and
