2011 ECOTEC 2.4L I-4 VVT DI (LAF)

Vehicle Applications

  • Buick LaCrosse
  • Buick Regal

Product Highlights

  • Precision sand-cast engine block
  • Pistons with jet-spray cooling
  • Strong SPM 319 aluminum cylinder head casting
  • DOHC with continuously variable valve timing
  • Direct injection
  • Cam-driven high-pressure fuel pump
  • 182 horsepower (136 kW) at 6,700 rpm
  • 172 lb.-ft. of torque (233 Nm) at 4,900 rpm

Overview

GM's versatile and technologically advanced Ecotec 2.4L engine is the standard engine in the new Buick Regal and the Buick LaCrosse CX. Direct injection technology helps it deliver 182 horsepower (136 kW) and 172 lb.-ft. of torque (233 Nm) in both models. Partnered with a six-speed automatic transmission, it helps provide excellent fuel economy, with an estimated 30 mpg highway for the Regal and LaCrosse.

With the Ecotec 2.4L's direct injection system, more power is made with less fuel, and the engine produces lower emissions. In fact, cold-start emissions are reduced by up to 25 percent. Engineers tuned the engine to deliver greater torque at lower rpm and build it smoothly toward its peak at 4,900 rpm, for excellent, confident performance in all driving conditions.

The Ecotec 2.4L (LAF) is based on the same engine found in other GM models, including the Chevrolet Malibu and GMC Terrain, but tailored specifically to Buick applications. As with other variants, 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.

Engine Block

The Ecotec 2.4L's sand-cast cylinder block is a superior refinement of previous Ecotec engine block castings. It is dimensionally similarwith previous variants, while providing excellent structural support, as well as enabling greater control of noise, vibration and harshness.

The main bearing bulkheads, which support the crank bearing, as well as the cylinder bore walls, have been significantly strengthened to support increased engine loads. Also, refinements to the oil distribution system enable improved oil flow throughout the engine; and 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.

Aluminum Pistons with Jet-Spray Cooling

The Ecotec 2.4L's pistons use lightweight aluminum pistons, for less reciprocating mass inside the enginethat enhances efficiency, decreases vibrationand bolsters the feeling of performance as rpm increases.

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 friction and operational noise, while also bolstering the engine's durability.

Cylinder Head

The Ecotec 2.4L has a SPM 319 aluminum cylinder head that is cast with advanced semi-permanent mold technology. This providesexcellent strength, reduced machining and optimal port flow. There is no need for heat treatment to the casting, which reduces residual stress and, consequently, enhances the engine's durability.

The cylinder head is designed specifically for direct injection into each combustion chamber. This is accomplished by positioning an injector under the intake port of each cylinder, so it protrudes into the chamber. The combustion chambers and ports are optimized for direct injection and high port flow.

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 alternative fuels such as E85. These premium materials, along with a hydraulic lash-adjusting lifter,ensure good durability without required lash adjustments.

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

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 2.4L'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 a 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 2.4L 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 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 mixtureand it operates at lower temperature than conventional port injection. Thisallows 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 reduces 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. 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.

With direct injection, the higher compression ratio is possible because of a cooling effect as the injected fuel vaporizes in the combustion chamber.This reduces the charge temperature and lessens 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 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 direct injection system in the Ecotec 2.4L. 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.

Oil and Filter Changes

Routine maintenance with the Ecotec 2.4L is limited to oil and filter changes; and thanks to a paper filter replacement cartridge,those are made as easy as possible.GM’s industry-leading Oil Life System determines oil-change intervals according to real-world operation rather than a predetermined mileage interval.

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