2010 - LAF Features and Benefits

[ZerOne]

2010 Ecotec 2.4L I-4, VVT DI (LAF)
2010 Model Year Summary

Content and benefits:
Direct Injection
Cam-Driven High-Pressure Fuel Pump
Advanced electronic control module (ECM) for direct injection control
SPM 319 Cylinder Head casting
Continuously Variable Valve Timing
Precision Sand Cast Engine Block
Pistons With Jet-Spray Cooling

New Chevrolet Equinox, GMC Terrain, and Buick LaCrosse will offer the Ecotec 2.4L I-4 VVT DI Engine (LAF)
The Ecotec 2.4L I-4 VVT DI (RPO LAF) powers the Chevrolet Equinox, GMC Terrain, and Buick LaCrosse for the 2010 model year. This Ecotec engine is installed transversely, and equipped with either a Hydra-Matic 6T45 FWD or AWD six-speed automatic transmission.

The 2.4L direct injection engine generates 182 horsepower and 172 lb.-ft. of torque.

Direct Injection
Given more than a century of development behind the internal-combustion engine, direct fuel injection is new technology. Direct injection is the culmination of the engineer’s quest to move the point where fuel feeds into an engine closer to the point where it ignites. The advantage is greater combustion efficiency. Direct injection allows the Ecotec 2.4L LAF engine to generate outstanding power, while consuming fuel at the more frugal rate of a conventional small-displacement port-injected engine.

Conventional port-injected engines inject fuel upstream of the intake valve into the intake port, and this fuel and air mixture enters the combustion chamber when the intake valve opens. On the direct-injection engine, fuel is injected directly into the combustion chamber during the intake stroke, at which time only air flows through the intake system and into the combustion chamber when the intake valve opens. During the subsequent compression stroke, the fuel and air mixture now in the combustion chamber is ignited conventionally by the spark plug. As the fuel vaporizes in the cylinder, the air and fuel mixture is cooled. This enables the use of a higher compression ratio in the combustion chamber, which improves engine performance and efficiency. Less fuel is required to produce the equivalent horsepower as a result of direct-injection technology compared to a conventional port-injection fuel system. Direct-injection technology also helps reduce cold-start emissions by approximately 25 percent.

The direct-injection fuel injectors inject fuel directly into the combustion chamber and are located beneath the intake ports, which transfer only air. Because the ports are not used to mix the fuel and air, efficiency of the air flow is increased. In addition, the control of the injection event, via direct-injection technology, is very precise and results in better combustion efficiency and fuel consumption at all throttle openings. A higher compression ratio is also possible due to a cooling effect as the injected fuel vaporizes in the combustion chamber. This cooling effect reduces the charge temperature reducing the likelihood of spark knock. The direct-injection fuel injectors have been developed to withstand the greater heat and pressure inside the combustion chamber, and also utilize multiple outlets for best injection control.

The increased combustion efficiency and control helps to reduce emissions, particularly during cold starts, which is when the bulk of emissions are created. Other things equal, using less fuel to do a given amount of work means fewer emissions generated when that work is finished. With direct injection, more thorough combustion means fewer emissions—essentially, residue—left to flow out the exhaust system after each combustion cycle.

Engineers have long understood the potential benefits of direct injection. The difficulty, until recently, has been the lack of technology to make it work properly: advanced fuel and spark timing to avoid detonation, or self-combustion out of sync with the spark; fuel delivery systems that can reliably generate and contain the extreme pressure required for direct injection. The fuel system operates at pressure as high as 2,250 psi, compared to as little as 60 psi in some conventional port-injected engines.

The benefits of direct injection are pronounced. The system allows a more complete burn of the fuel in the air-fuel mixture, and it operates at lower temperature than port injection. That allows the mixture to be leaner, meaning less fuel, more air. Less fuel is required to generate a given amount of horsepower, particularly at part-throttle operation. Bottom line: An engine with direct injection can deliver comparable power to a much larger displacement port-injected engine, with significant fuel savings.

High Pressure Cam-Driven Fuel Pump
A high-pressure, cam-driven pump provides the fuel pressure required for the direct injection system. The high-pressure pump is mounted on the end of the cylinder head and is driven by the intake cam. The engine mounted fuel pump is augmented by a conventional electrically operated supply pump in the fuel tank. The fuel delivery system features a high-pressure stainless steel feed line and a pressure-regulated fuel rail, without a conventional fuel return line from the engine to the tank.

Advanced electronic control module (ECM) for direct injection control
The engine management system uses a sophisticated controller (ECM) designed to drive the high pressure fuel system and provide software and calibration capability to control all of the engine's hardware and engine management systems.

All new SPM 319 Cylinder Head casting
The Ecotec 2.4L has a 319 aluminum cylinder head cast with advanced semi-permanent mold technology. This provides excellent strength, reduced machining, and improved port flow. No heat treatment to the casting also reduces residual stress, thus providing increased durability. The cylinder head is designed specifically for direct injection, where the fuel is injected into each combustion chamber. This is accomplished by positioning an injector under the intake port of each cylinder, such that they protrude into the chamber. In contrast, the previous 2.4L Ecotec engine had the fuel injectors mounted to inject fuel into the intake ports. The combustion chamber and ports are optimized for direct injection, and high port flow. This design supports improved performance, emissions and fuel economy over the previous combustion system.

The cylinder head includes premium valve seat, valve guide, and valve materials. They were selected for minimum wear while operating in more severe conditions associated with direct injection and alternate flex fuels, such as ethanol E85. These premium materials along with a hydraulic lash adjusting lifter assure good durability without required lash adjustments during the engine life cycle. Direct injection and flex fuels require a more robust valvetrain system due to the increased friction, higher thermal loads, increased oxidation and reduced lubrication associated with alternate fuels that do not contain some of the natural lubricants found in gasoline.

The cylinder head has integral cast oil passages that feed a set of internal oil control valves that activate cam phasers, enabling variable valve timing.

Continuously Variable Valve Timing
Continuously variable valve timing (VVT) optimizes the engine. Both the intake and exhaust cams have hydraulically operated vane-type phasers that are managed by a solenoid and directed by the engine control module (ECM). The phasers turn the camshaft relative to the drive sprocket, allowing intake and exhaust valve timing to be adjusted independently.

Cam phasing changes the timing of valve operation as conditions such as rpm and engine load vary. It allows an outstanding balance of smooth torque delivery over a broad rpm range, high specific output and good specific fuel consumption. Cam phasing also provides another effective tool for controlling exhaust emissions. Because it manages valve overlap at optimum levels, it eliminates the need for a separate exhaust gas recirculation (EGR) system. Variable valve timing can be even more valuable in turbocharged engine. The ECM can adjust valve overlap at low rpm to optimize turbo response, delivering a more immediate rush of acceleration-producing torque.

The cams feature 4X timing reluctors with digital sensors. This state-of–the-art control system allows the ECM to accurately measure and adjust valve timing, with consistent performance over the engine’s anticipated useful life. The cam reluctors work in conjunction with a 58X crankshaft position encoder to ensure the precisely accurate spark timing required of a direct-injection engine. This dual timing system also provides a reliable back up in the event either a cam or crank sensor fails.

Precision Sand Cast Engine Block
The Ecotec LAF sand cast cylinder block is a superior refinement of the 2.4L VVT (LE5) cylinder block which was first launched in 2006. The block was developed using the latest math-based tools for product design as well as for manufacturability.

From a design perspective, the main bearing bulkheads, which support the crank bearings, as well as the cylinder bore walls, have been significantly strengthened to support increased engine loads with only a minimal weight increase (approximately 2.2 pounds). Additionally, refinements to the oil distribution system enable improved oil flow throughout the LAF engine.

As the block casting is nearly common from a dimensional standpoint with previous Ecotec block variants, it provides improved structural support for the Ecotec LAF powerplant while continuing to be nearly transparent in machining and assembly operations.

All together, this means the block has been increased in strength to accommodate the additional power provided by SIDI while providing additional benefits in the areas of manufacturability and control of noise, vibration and harshness.

Aluminum Pistons with Jet-Spray Cooling
The LAF pistons use a lightweight design, resulting in less reciprocating mass inside the engine, increasing efficiency, decreasing vibration and enhancing the feeling of performance as the engine builds revs.

Each piston has its own directed 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 to match the engine’s high output.

Overview
Launched for model year 2000, the Ecotec 2.2L created a blueprint for subsequent global powertrain development and such engines as GM’s global V-6 VVT. It also laid the foundation for a line of engines that share core components with minimal casting changes, yet deliver unique performance and market characteristics with a range of displacements, direct or conventional injection, turbocharging, supercharging, hybrids and front-, rear- and all-wheel drive application in both cars and trucks. At 305 pounds fully dressed, the Ecotec 2.2L is the lightest engine GM has produced in its displacement class, and one of the most compact four-cylinders in the world.

All Ecotecs features durability enhancements and technology familiar in premium V-type engines, including low-friction hydraulic roller finger valve operation and electronic “drive-by-wire” throttle in most applications. A hydraulic tensioner keeps the timing chain adjusted for life, and extended-life spark plugs deliver 100,000 miles of service. Routine maintenance is limited to oil and filter changes, and even those are made as easy as possible with a paper filter replacement cartridge and GM’s industry-leading Oil Life System, which determines oil-change intervals according to real-world operation rather than a predetermined mileage interval. Every engine in the Ecotec line has aluminum-intensive construction and:

1• Dual overhead camshafts (DOHC) with four valves per cylinder
2• Twin counter-rotating balance shafts to cancel the second-order vibration typical in four-cylinder inline engines
3• Direct mounting of accessories like the alternator and compressor to eliminate common sources of noise, vibration and harshness
• Full circle transmission attachment and a structural oil
pan that bolts to both the engine block and transmission
bell housing.

For all its design and production efficiencies and multitude of applications, the Ecotec family succeeds for one reason. Each member is world-class four-cylinder that delivers excellent performance without sacrificing durability, economy or smooth, quiet operation.