LOS ANGELES – General Motors expands its new family of high-value V-6 engines with the introduction of a new, sophisticated 3500 3.5L V-6 that incorporates features such as cam phasing to deliver excellent power, economy and value.

The new generation of V-6 engines, introduced with the 3900 3.9L V-6, is the first overhead-valve engine family to incorporate variable valve timing, which optimizes performance and economy and promotes lower emissions at every rpm level. The 3500 V-6 debuts as the standard engine in the 2006 Chevy Impala and Monte Carlo . It will be available in two versions: an E85 ethanol fuel version (RPO code LZE), which allows the vehicle to run on any combination of gasoline and/or E85, and a non-E85 version (RPO code LZ4).

In these new vehicles, the 3500 V-6 is rated at 210 horsepower and 220 lb.-ft. of torque – a horsepower increase of more than 11 percent and a torque increase of 10 percent, when compared with the 2005 Impala’s 180 horsepower and 200 lb.- ft. The ’05 Impala features a 3400 V-6.

“The new 3500 V-6 is the second offspring of a brand-new family of engines that is designed to meet contemporary – and future – expectations for performance, economy, smoothness and durability,” said Gary Horvat, assistant chief engineer for V-6 engines. “The state-of-the-art technology built into this engine is evidenced by its combination of output and economy, attributes that continue to make the cam-in-block design relevant in the 21 st century.”

The new 3.5L and 3.9L V-6 engines share an all-new cylinder block casting and new cylinder heads. In fact, the new engine family share only valve lifters with any previous GM engine. Application of the 3.5L V-6 will spread to other high-volume GM vehicles, while the larger-displacement, more powerful 3.9L V-6 scheduled to debut in the 2006 Pontiac G6 GXP, also will be available in some 2006 Impala models. Both engines use the same new-family architecture, with more than 80-percent common components, but the 3.9L engine has a longer-stroke crankshaft to increase displacement.

Technical highlights of the new 3500 V-6 include:

Perhaps the most significant technological feature of the new 3.5L V-6 is the adaptation of variable valve timing – a first for cam-in-block engines. The system incorporates a vane-type camshaft phaser that changes the angular orientation of the camshaft, thereby adjusting the timing of the intake and exhaust valves to optimize performance and economy, and helping lower emissions. It offers infinitely variable valve timing in relation to the crankshaft.

The cam phasing creates “dual equal” valve timing adjustments. In other words, the intake valves and exhaust valves are varied at the same time and at the same rate. The cam phaser vane is attached to the camshaft on the front journal – a technique made easier by the award-winning “assembled-camshaft” design pioneered by General Motors. With this design, separate camshaft lobes are installed on a hollow camshaft tube rather than the traditional method of grinding a camshaft from a single piece of stock.

“ Cam phasing is kind of like having your cake and eating it too,” said Horvat. “With it, the engine can be ‘cammed’ for horsepower at certain rpm, but adjusted to deliver low-end torque and all-around economy.”

Hydraulic roller lifters with low-friction followers complement the unique camshaft and a new, more powerful E67 ECM, with its 32-bit processor, enables the engine’s cam phasing. Variable valve timing also necessitated a more precise cam position sensor, so engineers developed a new cam target ring. The ring has four equally spaced segments that communicate the camshaft’s position quicker and more accurately than previous systems that used just a single segment. Also, a leaf spring-type tensioner is used on the timing chain to ensure precise tension.

The 3.5L V-6’s camshaft is unique and matched to the engine’s bore-and-stroke characteristics. It is different, for example, than the camshaft in the 3.9L V-6. With cam phasing, the 2006 Impala is expected to meet the LEV II emissions standard.

Balance and power

The 3.5L and 3.9L V-6 engines represent an all-new engine design, but incorporate some familiar and well-regarded attributes, including a 60-degree “V” configuration. The 60-degree configuration is naturally balanced, ensuring drivetrain smoothness and eliminating the need for costly balance shafts. The relatively narrow 60-degree V also makes the engine more compact for a variety of applications.

This new engine differs from previous GM 60-degree designs with its offset cylinder bores, meaning the intersection of the cylinder bores’ centerline is not at the crankshaft centerline. Instead, the intersection is 3 mm below the crankshaft axis. This was done to allow packaging room for the wider bores, as well as the longer stroke of larger-displacement versions within the new engine family. It also allowed for larger cam bearings which, in turn, promoted increased horsepower as larger cam bearings supported the use of a camshaft with higher valve lift profile.

The bores of the engine measure 99 mm (3.90-in.) in diameter, which is 7 mm larger than the 92-mm (3.62-in.) bores in the 2005 Impala’s V-6 engine. In fact, it’s the same bore diameter as the Gen III 5.7-liter LS1 small-block V-8 used in the 2004 Corvette.

“The wider bore really helps make great horsepower, and the 99-mm bore diameter works well in this engine, just as it does in other high-performance GM engines, like the LS1,” said Horvat.

Indeed, cylinder bore diameter wasn’t the only chapter taken from the GM small-block performance playbook. The valve spring rocker arms are the same parts used in the LS1. And when it comes to the cylinder heads, the 3.5L V-6’s valves are nearly LS1-sized, too, with 47.5-mm intake valves and 38.7-mm exhaust valves.

The valves are housed in aluminum heads that are cast in a semi-permanent mold, which improves overall strength. Engineers studied LS1 and LS6 combustion characteristics to help achieve strong performance and efficiency. The large valve size and combustion chamber design optimize the airflow of the large-bore cylinders.

Exhaust exits the cylinder heads through newly design exhaust manifolds that are tuned for increased performance. The manifolds feature laminated heat shields.

Cool flow

A new “U”-shaped coolant flow system is used in this new engine family. With it, coolant follows a specific path: it enters the engine at the front of the block and is carried to the back, before flowing into the rear of the cylinder head. As the coolant enters the rear of the cylinder head it flows forward, completing a U-shaped path that delivers more uniform cooling than the previous engine.

The water pump is mounted approximately 4 inches lower in the coolant’s path, which helps ensure steady flow if the system loses a small quantity of coolant. The new cooling system design also incorporates a coolant crossover at the front of the engine and requires no coolant to enter the intake manifold.

Engineers also placed the thermostat on the inlet side of the system, which allows the engine – and the vehicle’s interior – to warm up more quickly in cold weather. Also, the coolant system has an on-engine fill point. It is located at the high-point in the system (near the power steering pump), easing the task of adding coolant because air cannot be trapped. Therefore, no “burping” of the system through bleed screws is required.

E85 capability

Vehicles equipped with the 3.5L V-6 and sold in the United States are compatible with E85 ethanol-based fuel, offering a good environmental alternative to gasoline. With its new, sophisticated virtual sensor, the 3.5L V-6 can run on any combination of gasoline and/or E85 fuel. (E85 capability is optional on vehicles in Canada .)

The engine control system samples the exhaust at the oxygen sensor, and an algorithm determines whether E85 is used, as well as its mixture percentage with gasoline. It’s a much simpler, less costly system than previous system that relied on fuel composition sensors. In fact, the entire system on the engine is simple: only the fuel rail and fuel injectors are different between the E85 version and non-E85 version.

E85 is a clean-burning alternative fuel made in the United States with homegrown corn and other crops. E85 is largely alcohol, composed of 85 percent ethanol and 15 percent gasoline. The alcohol is produced by fermenting plant sugars.

E85 nearly eliminates greenhouse gas emissions from automobiles, is biodegradable, it doesn’t contaminate the water supply, and can be produced from various feedstocks, including grain, corn and wheat stalks, forestry and agricultural waste, and even municipal waste.

One-third of the 4 million E85 vehicles on the road today are GM vehicles.

Unexpected refinements

The 3.5L V-6 incorporates a host of features and refinements typically reserved for high-cost premium engines:

Oil piston coolers – Every cylinder has piston oil squirters that ensure optimal lubrication and cooling.

Multi-layer steel (MLS) head gaskets – These premium gaskets offer great durability over conventional graphite gaskets and were validated to 150,000 miles.

58X Quick Sync ignition – The 3.5L V-6’s direct ignition system uses 58 sensors to more accurately determine the position of the crankshaft, ensuring extremely accurate ignition performance.

Aluminum intake system – The upper and lower plenums of the equal-length intake manifold are made from cast aluminum, which offers better NVH and heat absorption characteristics than typical composite plastic intakes.

Electronic throttle control (ETC) – Throttle operation is handled by more accurate electronic signals, eliminating the need for conventional throttle cables. Cruise control functions are incorporated with ETC, reducing underhood complexity. The engine draws air through a 72-mm single-bore throttle body.

Next-gen Multec 3.5 fuel injectors – Part of the engine’s returnless fuel system, these next-generation fuel injectors have improved hot fuel handling characteristics and improved plug resistance. Injectors in E85-capable engines have a diamond-like coating on the injector valve.

The 3.5L V-6 also incorporates long-life components such as 100,000-mile iridium-tip spark plugs and coolant, as well as premium gaskets and sealers that help ensure maintenance-free operation. The GM Oil Life System (GMOLS) also is standard.

GMOLS can extend the intervals between oil changes and reduce the amount of oil an owner buys over the operating life of the vehicle. With GMOLS, the need for an oil change is determined by an algorithm that measures engine starts, temperature and other factors. An indicator on the instrument panel illuminates when it’s time for an oil change.

The 3500 3.5L V-6 is assembled at GM Powertrain’s Tonawanda , N.Y. assembly facility.

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Nick Richards
GM Powertrain Communications
Phone: (248) 857-0163

3500 3.5L V-6 Specifications
Assembly site: Tonawanda, NY
Applications: Chevrolet Impala and Monte Carlo
Type: 3.5L OHV V-6 with cam phasing (RPO LZE and LZ4)
Displacement (cu in / cc): 214 / 3510
Bore x stroke (in / mm): 3.90 x 2.99 / 99 x 76
Block material: cast iron
Main bearing caps powder metal (1, 2, 3); cast nodular iron (4)
Cylinder head material: cast aluminum
Intake manifold: cast aluminum
Exhaust manifolds: high-silicon molybdenum, cast nodular iron
Compression ratio: 9.8:1
Valve configuration: overhead valves (2 valves per cylinder)
Valve lifters: hydraulic roller
Firing order: 1 - 2 - 3 - 4 - 5 - 6
Fuel system: sequential fuel injection
Horsepower (hp / kw): 210 / 156.5 @ 5900 rpm
Torque (lb-ft / Nm): 220 / 304 @ 2800 rpm
Fuel shut off: 6400 rpm
Emissions controls: Catalytic converter, evaporative system, positive crankcase ventilation
Crankshaft: steel
Camshaft: assembled steel
Connecting rods: forged powder metal
Additional features: electronic throttle control, dual equal continuously variable valve timing, roller rocker arms, pressure-actuated piston cooling jets, extended-life spark plugs, extended-life coolant, GM Oil Life System, oil level sensor, extended-life accessory drive belt