Advanced Technologies Enhance 2015 Tahoe and Suburban Efficiency

2014-02-25


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LAKE TAHOE, Calif. (Tuesday, February 25, 2014) – Tahoe and Suburban’s standard 5.3L V-8 engine, rated at 355 horsepower (265 kW) and 383 lb.-ft. of torque (519 Nm), features state-of-the-art technologies including direct injection, cylinder deactivation, continuously variable valve timing and an advanced combustion system, all designed to make the most of power, torque and efficiency across a broad range of operating conditions.

Improved engine mounts, electronic throttle control, adaptive exhaust systems, improved aerodynamics and other technologies help the engines operate in four-cylinder mode longer with Active Fuel Management, further increasing efficiency.

The Tahoe and Suburban deliver a fuel efficiency rating of 14.9 L/100kmcity and 10.1 L/100km highway (2WD) – a 9-percent improvement on highway over the previous models and 7-percent greater in city.

A Hydra-Matic 6L80 six-speed automatic transmission is paired with the new 5.3L engine and contributes to efficiency with reduced engine speed on the highway. It also features TapShift control, Tow/Haul mode and Auto Grade Braking.

Advanced combustion system

At the heart of the new EcoTec3 engine family is an advanced combustion system that maximizes the potential of the direct fuel injection system, cylinder deactivation, continuously variable valve timing and other technologies to ensure a strong balance between on-demand performance and real-world efficiency.

The ability to more precisely control combustion also enables the new engines to run with a higher compression ratio, one of the best ways to simultaneously increase power and efficiency.

“Customers use the Tahoe and Suburban for everything from school runs to towing boats, and we’ve developed a powertrain that delivers greater efficiency without sacrificing the power they expect from a Chevrolet SUV,” said Sheryl Balsley, assistant chief engineer for Small Block engines. “The capability of the engine to instantly switch to four-cylinder mode, for example, improves efficiency when less power is required, but delivers full eight-cylinder power whenever it’s needed.”

This increased efficiency can now be maintained over a broader range of operating conditions.  For example, when towing a trailer on a steep grade on a hot day, the advanced combustion system can reduce the need to trim back spark advance to control detonation, helping maintain efficiency with confident performance.

Direct injection and Active Fuel Management

The 5.3L’s direct fuel injection system precisely meters fuel directly into the cylinders, helping optimize combustion over a broad range of conditions. An all-new cylinder head design supports the fuel system and it’s complemented by a new, sculpted piston head developed to direct the injector’s fuel spray for better mixing and more complete combustion.  

To further enhance combustion, the intake and exhaust valve positions have been switched from the previous Small Block engine design, and the spark plug angle has been revised to move the electrode now closer to the center of the chamber to support optimal combustion.

In certain light-load driving conditions, half of the 5.3L’s injectors quit spraying fuel, effectively turning the engine into a V-4 to help increase efficiency. This cylinder deactivation technology, also known as Active Fuel Management, is standard and uses oil pressure, controlled by the powertrain control module, to deactivate the lifters on selected cylinders, closes the valves for those cylinders, and seamlessly reactivates the cylinders when the driver demands greater power. The transition takes less than 20 milliseconds and is virtually imperceptible.

“This is another great example of using a relatively simple mechanical system and powerful software to provide a real benefit to our customers,” said Balsley.

Additional features on the EcoTec3 5.3L include:

Weight-saving aluminum engine block: A lightweight aluminum block with iron cylinder liners provides a light, rigid foundation for a smooth and strong engine. The deep-skirt block design helps maximize strength and minimize vibration. Cross-bolted main bearing caps are secured to the block with four main bolts and two cross bolts each. A structural aluminum oil pan further stiffens the bottom of the block. The result is an engine that is quieter, smoother and more dependable, even under the toughest conditions.

Efficiency-enhancing oiling system: The oiling system incorporates a new variable-displacement oil pump that enables more efficient oil delivery, based on the engine’s operating conditions. Its dual-pressure control enables operation at a very efficient oil pressure at lower rpm, and then delivers higher pressure at higher engine speeds to provide a more robust lubrication.

The 5.3L uses GM’s Dexos oil for increased efficiency and longer oil life. GM’s oil life monitoring system is standard and helps protect the engine by indicating oil changes based on operating conditions, which can also save money by avoiding unnecessary oil changes.

Oil-jet piston cooling: At higher engine speeds, small jets spray oil on the underside of each piston to help reduce piston temperature, enabling the engine to maintain maximum horsepower and torque. It also reduces engine noise.

PCV-integrated rocker covers: New domed rocker covers house a patent-pending integrated positive crankcase ventilation system that enhances oil life, reduces oil consumption and reduces exhaust emissions. The domed sections of the covers contain baffles that separate oil and air from the crankcase gases, with about three times the oil/air separation capability of previous engines.

“Saw-cut” exhaust manifolds: The cast-iron exhaust manifolds were developed to improve durability and sealing, and reduce operating noise. They feature saw cuts along their cylinder head mounting flange, which split the flange into four separate sections, allowing each section to move under extreme hot-cold temperature fluctuations to virtually eliminate movement of the exhaust manifold gaskets. That helps ensure proper sealing for the life of the engine and reduces the chance of gasket failure. The exhaust manifolds also feature triple-layer stainless steel heat shields, which limit heat transfer to the engine bay and help further reduce noise.

Cooling system, humidity sensor and more:

  • A revised cooling system with an offset water pump and thermostat delivers more efficient performance
  • An air induction humidity sensor ensures optimal combustion efficiency, regardless of the surrounding air’s humidity
  • An engine-driven mechanical vacuum pump enhances braking performance
  • 58X ignition system with individual ignition coil modules and iridium-tip spark plugs contribute to greater efficiency and reduced maintenance requirements.

Small Block legacy

The first Small Block V-8 was introduced in 1955 – a 4.3L V-8 that was an option in the Suburban. It was rated at 145 horsepower and 238 lb.-ft. of torque. Sixty years later, the new EcoTec3 5.3L Small Block produces 245 percent more horsepower and 61 percent more torque from only 23 percent greater engine displacement.

The new 5.3L is built on a foundation of more than 100 million Small Block engines and four generations that came before it. Engines based on the architecture are typically smaller and lighter than competitors’ engines with overhead camshafts, and typically have lower friction – attributes that can enhance efficiency.

About Chevrolet in Canada

Founded in 1911 in Detroit, Chevrolet is now one of the world's largest car brands, doing business in more than 140 countries and selling more than 4.5 million cars and trucks a year. Chevrolet provides customers with fuel-efficient vehicles that feature spirited performance, expressive design and high quality. More information on Chevrolet models can be found at www.chevrolet.ca, on Facebook at http://www.facebook.com/chevroletcanada or by following @ChevroletCanada on Twitter.

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