2012 Ecotec 2.0L I-4 Vvt Di Turbo (Lhu)

2012 ECOTEC 2.0L I-4 VVT DI TURBO (LHU)

Vehicle Applications

Buick Regal / Regal GS

Product Highlights

• Twin-scroll turbocharger
• Air-to-air intercooler
• Gen II sand-cast engine block
• Forged steel crankshaft
• Aluminum pistons with jet-spray cooling
• Rotocast aluminum cylinder head with sodium-filled exhaust valves
• DOHC with continuously variable valve timing
• Direct injection
• Cam-driven high-pressure fuel pump
• E85 flex-fuel capable
• Cam-driven vacuum pump

Overview

Available in the Buick Regal CXL, the Ecotec 2.0L turbo (LHU) is a next-generation derivative of the advanced Ecotec 2.0L turbo LNF engine, which introduced for the 2007 model year and was the first North American engine with direct injection. It is tuned to meet the unique performance, efficiency and quietness targets of the Buick Regal and Regal GS.

The Regal is a global car and the Ecotec 2.0L turbo's development applied the best practices of technical centers in Europe and North America. It was subjected to one of the toughest, most comprehensive validation processes ever at GM, which included millions of miles of real-world road testing in a broad range of climates and environments. The result is a powerful and efficient engine that delivers the smoothness and quietness commensurate with Buick.

As with all Ecotec engines, it features durability and technology features familiar in premium V-type engines, including low-friction hydraulic roller-finger valve operation and an electronic throttle. A hydraulic tensioner keeps the timing chain adjusted for life, and extended-life spark plugs deliver 100,000 miles (160,000 km) of service.

Additional Ecotec family traits include:

• Dual overhead camshafts (DOHC) with four valves per cylinder
• Twin counter-rotating balance shafts to cancel the second-order vibration typical in four-cylinder inline engines
• Full-circle transmission attachment and a structural oil pan that bolts to both the engine block and transmission bell housing.

Gen II Engine Block

The Ecotec 2.0L turbo sand-cast cylinder block is a superior refinement of previous Ecotec engine block castings. It is dimensionally similarwith previous Ecotec turbo block variants, while providing improved structural support, as well as enabling greater control of noise, vibration and harshness.

The main bearing bulkheads, which support the crank bearings, as well as the cylinder bore wallshave been significantly strengthened to support increased engine loads. Refinements to the oil distribution system enable improved oil flow throughout the engineand an expansion of the coolant jacket, along with the use of cast-in-place bore liners, allows more precise bore roundness and improves the block’s ability to dissipate heat.

Rotating Assembly

The crankshaft is made of drop forged steelwith induction heat-treated fillets and cross-drilledchamfered oil passages for racing-grade lubrication characteristics. Forged powdered metal connecting rods incorporate a larger, forged I-beam cross section for added strength in this turbocharged application.

The pistons in the 2.0L turbo are lightweight cast aluminum, which reduces reciprocating mass inside the engine. This enhances efficiency and the feeling of performance as the rpm increases. The tops of the pistonshave a dish shape that deflects injected fuel toward the spark plugs, optimizing the thorough-combustion benefits of direct injection.

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, reduces both friction and operational noise and bolsters the engine's durability.

RotocastAluminum Cylinder Head with Sodium Filled Exhaust Valves

The Ecotec 2.0L turbo's A356 aluminum cylinder head is cast using a Rotocast process for high strength, reduced machining and improved port flow. The head is also designed specifically for direct injection. In other Ecotec engines, the fuel injectors are mounted in the intake portsbut the 2.0L turbo head has unique injector mounting locations below the ports. Apart from injector installation, the head has conventional port and combustion chamber designs, both are optimized for direct injection and high boost pressure.

The head uses stainless steel intake valves that arenitrided for improved durability and undercut to improve flow and reduce weight. The exhaust valves have sodium-filled stems that promote valve cooling. At normal engine operating temperatures, the sodium inside the valve stem fuses and becomes liquid. The liquid sodium improves conductivity, promoting heat transfer away from the valve face and valve guide to the cooler end of the stem, where it more readily dissipates. This helps maintain a lower, more uniform valve temperature, reducing wear on the valve guide for better alignment and a consistent seal between the valve seat and valve face over the life of the engine.

Performance was the priority with the Ecotec 2.0L turbo, so the exhaust manifold mounted to the cylinder head is made of cast stainless steel. It is extremely durable and delivers exceptional airflow qualities.

DOHC with Continuously Variable Valve Timing

Overhead cams are the most direct, efficient means of operating the valves, while four valves per cylinder increase airflow in and out of the engine. This arrangement is integrated on the Ecotec 2.0L's lightweight aluminum cylinder head.

Continuously variable valve timing optimizes the engine's turbocharging system by adjusting valve timing at lower rpm for improved turbo response and greater torque delivery. 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 separateexhaust 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 Ecotec 2.0L turbo camshafts 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 backup in the event either a camshaft or crankshaft sensor fails.

Direct Injection

Direct injection moves the point where fuel feeds into an engine closer to the point where it ignites, enabling greater combustion efficiency. It fosters a more complete burn of the fuel in the air-fuel mixture, and operates at a lower temperature than conventional port injection. This allows the mixture to be leaner (less fuel and more air), so less fuel is required to produce the equivalent horsepower of a conventional, port-injection fuel system. Direct injection also delivers reduced emissions, particularly cold-start emissions, by about 25 percent.

The direct injection fuel injectors introduce fuel directly into the combustion chambers 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 airflow is increased. Also, 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.

The higher compression ratio with direct injection is possible because of a cooling effect as the injected fuel vaporizes in the combustion chamber, which reduces the charge temperature to lessen 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 feature multiple outlets for best injection control. The fuel system operates at pressure as high as 2,250 psi, compared to about 60 psi in conventional port-injected engines.

Cam-Driven High-Pressure Fuel Pump

A high-pressure, cam-driven pump provides the fuel pressure required of the Ecotec 2.0L turbo’s direct injection system. 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. Fuel pressure varies from about 750 psi at idle to 2,250 psi at wide-open throttle.

E85 Flex-Fuel Capability

E85 is a clean-burning alternative fuel made in the United States, composed of 85 percent ethanol alcohol and 15 percent gasoline. Ethanol is biodegradable and doesn't contaminate the water supply. It can be produced from various feed stocks, including corn and wheat stalks, forestry byproducts, and agricultural and municipal waste.

The Ecotec 2.0L turbo's flex-fuel technology is both sophisticated and durable. Hardware changes are limited to the injectors with a higher maximum flow rating.

Twin-Scroll Turbocharger

An advanced, electronically controlled turbocharger with a unique twin-scroll design is used to increase power in the Ecotec 2.0L turbo. Each of two scrolls on the turbine is fed by a separate exhaust passage – one from cylinders one and four, the other from cylinders two and three – to virtually eliminates turbo lag at low engine speeds, giving the engine immediate throttle response associated with a naturally aspirated high-performance engine.

The turbocharger generates maximum boost of about 20 psi. Because direct injection cools the intake process compared to port injection, it allows the Ecotec 2.0L turbo to safely operate at higher boost and a relatively higher compression (9.2:1) than a conventional turbo engine, increasing both output and efficiency.

Air-to-Air Intercooler

An intake charge cooler enhances the power-increasing benefits of the turbocharging system. The Ecotec 2.0L turbo’s air-to-air intercooler draws fresh air through a heat exchanger – much like a radiator – to reduce the temperature of compressed air that’s forced through the intake system by the turbocharger. Inlet temperature is reduced as much as 212 degrees F. Cooler air is denser, which means more oxygen is packed in the cylinders for optimal combustion and, consequently,greater power.

Cam-Driven Vacuum Pump

A cam-driven vacuum pump ensures the availability of vacuum under all conditions, especially under boost, when the engine produces the opposite of vacuum. The pump is mounted at the rear of the cylinder head and is driven by the exhaust camshaft via a flexible coupling.

Oil and Filter Changes

Routine maintenance with the Ecotec 2.0L turbo 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.

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