Leveraging the technology of its highly successful Vortec 4200 inline six-cylinder engine, GM has created two additional inline engines with excellent driveability features for mid-size pickup customers: the Vortec 3500 inline five-cylinder and Vortec 2800 inline four-cylinder engines. Both engines will be available in the 2004 Chevrolet Colorado and GMC Canyon and will provide the power of a V6 and the efficiency of an I-4.

Common Design

The Vortec 3500 and Vortec 2800 are, in large measure, scaled down versions of the award-winning Vortec 4200 six-cylinder engine.

With their common design, the new inline I-5 and I-4 engines feature the same all-aluminum construction, dual overhead camshafts and four-valves-per-cylinder technology as the Vortec 4200. The new engines also share the I-6’s high 10:1 compression ratio, electronic throttle control, exhaust cam phasing, coil-on-plug ignition, direct-mount accessories and easy maintenance features.

The cast aluminum four- and five-cylinder engine blocks and aluminum cylinder heads are produced using the same "lost foam" casting process as the Vortec 4200. This process allows more exact dimensional control while reducing machining efforts in oil galleries, coolant and other internal passages.

Overall, the new engines share 75 percent of their components with Vortec 4200 and 89 percent of their components with each other. This provides customers with highly proven design features and enables GM to develop and introduce them more quickly and at a lower cost. Commonality also allows the engines to be manufactured more cost effectively and gives GM a unique ability to adjust production in response to changing market trends.

The Vortec 3500 I-5 is targeted to produce 215 horsepower and 225 lb-ft of torque. The Vortec 2800 I-4 is targeted to deliver 170 horsepower and 175 lb-ft of torque.

"The real key to these engines is that they’re part of a carefully planned and developed inline family," said Ron Kociba, Vortec inline engine chief engineer. "The Vortec 4200 I-6 was the first and the I-5 and I-4 take advantage of much of the same technology to provide the same benefits for pickup truck customers as the I-6 provides in the SUVs."

Distinguishing Features

A major differentiating feature between the Vortec 3500 and 2800 engines is their dual balance-shaft system. The balance shafts offset secondary forces inherent to inline engines and help to provide smooth, quiet operation throughout the entire operating range.

Incorporated into housings on each side of the engine block, the balance shafts rotate in opposite directions of one another at twice engine speed, countering secondary forces generated by piston movement. They help eliminate vibrations that drivers and passengers might otherwise feel transmitted through the engine mounts to the steering wheel, seats, floor pan or instrument panel.

A rigid block structure and well-balanced crankshaft are also key to low noise, vibration and harshness. The Vortec 3500 crankshaft is optimally counterweighted for its five-cylinder design. Many of the same features used to control noise and vibration on the I-6 engine are found in the I-4 and I-5, such as isolated cam covers and acoustic foam treated induction manifolds, as well as attention to detail in the design process.

A unique manifold-mounted converter – a three-way catalyst constructed as part of the exhaust manifold – also sets the I-5 and I-4 engines apart from the I-6, and enables them to meet foreseeable future emissions requirements with no change in basic configuration. The new engines are designed to meet Federal Tier II / California Low Emission Vehicle II (LEV II).

Close-coupled catalytic converters provide optimum initial "light off" (quick, high temperatures), primarily for oxidizing hydrocarbon and carbon monoxide emissions, with an under-floor catalyst burning the majority of remaining gases.

The engines’ exhaust cam phaser is a common feature to the Vortec inline engine family used to enable variable valve timing (VVT). This technology allows more freedom in cam profile selection, which enhances power and torque. It also improves idle smoothness, reduces emissions and improves fuel economy.

VVT is used to time and regulate the opening and closing of the exhaust valves. The valve timing is electronically controlled and programmed for optimum emissions, torque, smooth idle and driveability.

Increasing the overlap of the cams, or "retarding the exhaust cam," creates internal exhaust gas recirculation (EGR) in which gases are evenly distributed to all cylinders. Leftover gases are simply recycled into the next burn cycle – an enabler for emissions control also providing high output and smooth idle.

The new engines use a more powerful, next-generation powertrain control module (PCM), with a new GM common design. The PCM manages all engine and transmission functions and communicates with other electronic vehicle controls. The new PCM provides quicker response time and has flash programmable memory, allowing quick and easy reprogramming to accomodate new features and updates. GM is pursuing commonality in its PCMs to reduce engineering time and cost and to help bring new vehicles to market more quickly.

Technology Highlighted

Among the Vortec 3500 and 2800 key features:

• Standard electronic throttle control (ETC) allows precise tailoring of throttle progression in each of the engines to meet its particular character. ETC optimizes driveability, fuel economy and emissions control, and enables other functions, such as cruise control, brake-torque management and traction control, available on two-wheel-drive models.

A controller, integrated into the dual microprocessor PCM, manages the electronic throttle. Based on information from two independent throttle position sensors and other data, such as the transmission gear and traction at the wheels, the PCM directs an electric motor to open the throttle at an appropriate rate.

• The coil-on-plug ignition system delivers a high-energy spark, which contributes to clean and consistent combustion, enabling compliance with emissions and onboard diagnostic misfire requirements. The electronic engine-sensing and spark control system also contributes to improvements in fuel economy, high-speed performance and engine efficiency. It has no moving parts, requires no timing adjustments and eliminates the need for spark plug wires.

The roller follower valvetrain and state-of-the-art PCM also improve engine performance, efficiency and noise levels.
An "intelligent start" feature prevents drivers from inadvertently engaging the starter on these smooth, quiet engines when they are already running.

Smooth-Shifting Transmissions

Available with both the Vortec 3500 and 2800 engines is the precisely controlled, smooth shifting Hydra-Matic 4L60-E 4-speed automatic transmission. Used in all of GM’s light-duty applications, it has a long history of customer-pleasing performance and dependability.

Both the Vortec 3500 and 2800 also link to a standard new high-torque capacity five-speed manual transmission. Used by GM for the first time, it provides smoother, higher quality shifts; better launch; improved durability and a higher degree of fuel efficiency.

Manufacturing Flexibility

From a manufacturing standpoint, GM’s Vortec inline family program provides a unique flexibility to respond more quickly and in less costly fashion to any future shifts in engine demand.

"You can flex four-, five-, and six-cylinder engines a whole lot easier than you can flex from a V8 to a V6 or even to four-cylinder, which gets pretty tough," Kociba said.

As indicated, the Vortec inline family has a high degree of parts commonality, allowing these components to be machined on the same equipment. The Vortec 3500 will share manufacturing space with the Vortec 2800 in a new facility at GM’s Tonawanda, N.Y., engine plant.

The Vortec inline engine family also provides a strong foundation from which to add other potential technologies, such as full variable valve timing (for both intake and exhaust), turbocharging, direct injection-gasoline or potentially larger displacements.

"Long term, we’ll continue to investigate new technologies," said Kociba. "We’ve created this engine family to have a long life and designed an architecture for any of those add-ons, if we determine a demand for them."

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