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2005 Pontiac Montana SV6: Powertrain and Chassis Systems

ENGINE: 3500 V-6

Developed for power, economy, reduced emissions and smooth, quiet performance, a high-value 3500 V-6 drives the Montana SV6. Rated at 200 horsepower and 220 lb.-ft. of torque, the 3500's broad performance range provides responsive driving dynamics - stirring attributes commensurate with Pontiac's performance renaissance.

To deliver on the SV6's promise of performance, economy and quality, engineers established several powertrain benchmarks:

- Increase power and performance
- Provide 0-to-60 performance of 10 seconds or less
- Provide 45-65 mph passing performance of at least 6.4 seconds
- Reduce noise and vibration
- Provide fuel economy near the top of the mid-van segment - preliminary ratings for front-drive models are 18 mpg in the city and 25 mpg on the highway
- Reduce emissions to meet all Level II California, Northeast and Federal standards for 2005
- Provide higher levels of quality, reliability and dependability.

The SV6's high-value V-6 is the newest member of GM's popular 60-degree overhead-valve V-6 engine family. With 3.5 liters (213 cubic inches) and sequential port fuel injection (SPFI), the 3500 delivers the power and performance to suit CSV customers' needs.

"It's power you feel immediately," said Anna Kretz, vehicle line executive for front-wheel-drive trucks. "The responsiveness of the engine contributes to a lively, spirited driving experience."

It also is a smooth and quiet driving experience, thanks to a host of features designed to give the 3500 V-6 exceptionally low noise and vibration. The cast iron engine block features a large-pin iron crankshaft designed to reduce resonation and vibration, and the crankshaft journals, on which the connecting rod/piston assemblies are attached, also are larger, reducing flex that could cause vibration.

Other features designed to improve the engine's noise and vibration characteristics include optimized crankshaft counterweights, a tuned length intake manifold, laminated exhaust manifold heat shields, and an engine-mounted EVAP solenoid. The EVAP solenoid is traditionally a device mounted to the underhood bodywork. By mounting it to the engine, noise is not transmitted through the SV6's body structure.

The 3500 also has been fitted with numerous components and features to ensure its quality and reliability are as strong as its smooth performance. These features include:

- Dual-response flat knock sensors - better detection range to provide the powertrain control module with better feedback for improved spark control.
- Improved mass airflow sensor - new design with output calibration precisely programmed into the module.
- Piston cooling squirters - sprays oil at the bottom of pistons 5 and 6 (the engine's hottest bores due to their distance from the cooling system) to ensure cooling and lubrication.
- Iridium spark plugs - with platinum tips, these 100,000-mile plugs are extremely resistant to erosion and handle leaner air/fuel ratios for better engine performance.

Reduced emissions, longer range

Montana SV6's engine meets or exceeds the stringent 2005 emissions standards for California, the Northeast Region and the federal government. And with its efficient performance combined with a standard 25-gallon fuel tank, a front-drive SV6 can go up to 625 miles between fill-ups.

"Simply put, the SV6 was designed to be a clean, low-maintenance vehicle," said Kretz. "With all the other things that busy families have to deal with, worrying about the SV6's operation won't be one of them."

Numerous innovations and refinements ensure the SV6 delivers outstanding emissions performance, including the areas of evaporative emissions, hydrocarobons, NOx and carbon monoxide. A more powerful, next-generation PO5 powertrain control module (PCM) provides increased processing power and engine control capability to continually adjust the engine's tuning for optimal performance and emissions.

The PO5 PCM is a 16.7 MHz, 32-bit processor that enables hundreds of measurements per second, enabling "real time" adjustment of fuel, air and spark. In addition to optimized performance and emissions, this new controller also improves cold weather starting, extends engine life while reducing maintenance intervals, and enables smoother, more responsive acceleration.

Complementing the PO5 controller is the Quick-Sync 24X ignition system, which enables the controller to determine the exact location of the pistons in the cylinders at start up. Hydrocarbon emissions are reduced because the controller is better able to control the fuel and spark in the individual cylinders when the engine is started.

A returnless fuel system, along with improved fuel injectors, also helps reduce evaporative emissions because the warmer, unused fuel of a conventional return system is not routed back to the fuel tank. The injectors are designed for industry-leading standards for long-term emissions and driveability. Additionally, the 3500 is equipped with a next-generation oxygen sensor that provides quicker detection of air/fuel ratios, enabling the PO5 controller to continuously optimize fuel injection to the engine.

The 3500 V-6 also incorporates a single exhaust system and close-coupled catalytic converters. Mounted near the exhaust manifolds, the converters "light off" faster after start up - the period where 80 percent of NOx gases are emitted - because heat is transferred from the manifolds more immediately. This configuration dramatically reduces NOx when compared with a conventional, under-floor catalyst system.

TRANSMISSION: Hydra-Matic 4T65-E four-speed automatic

The 3500 V-6 is backed by the proven Hydra-Matic 4T65-E electronically controlled four-speed automatic transmission. Developed for high-torque, front-drive applications, the 4T65-E delivers outstanding shift smoothness and operational quietness.

Sophisticated electronics in the transmission modify shift patterns as driving conditions warrant. An electronically controlled capacity clutch, rather than a mechanically controlled lock-up clutch, employs sophisticated electronics to maintain very small amounts of slip between the pressure plate and the torque converter housing cover. The ability to precisely control continuously variable amounts of slip reduces torque pulses and allows the clutch to be applied at lower vehicle speeds with smoother engagement. Overall, this improves driveability and fuel economy.

The PCM monitors factors such as throttle position, vehicle speed, gear range, temperature and engine load to continually provide optimum shifting. The PCM also measures changes in the operating condition of the vehicle, which occur naturally over time as components wear. Based on these measurements, shift timing and hydraulic line pressure are adapted to maintain optimum shift feel under different conditions - such as at high altitude, when the engine would normally feel sluggish because of a lack of oxygen.

Additionally, the 4T65-E delivers smooth, reliable performance and low maintenance needs with these built-in features:

- Electronic safeguards that protect the transmission from potentially damaging conditions, such as inadvertently leaving the transmission in a lower gear or rocking the vehicle in snow or mud. A "limp home" mode enables the vehicle to be driven at reduced speed even after an extreme heat-related failure.
- A "garage shift" feature reduces noise and vibration in low-speed parking maneuvers with optimized hydraulic calibrations and mechanical components.
- DEXRON III transmission fluid, which has a 100,000-mile service interval, is used. Additionally, the PCM monitors operating conditions of the transaxle and alerts the driver with a warning light if there is a deterioration that would cause the vehicle to exceed acceptable emissions levels, in compliance with 2005 OBD regulations. Special friction material in the second, third and fourth clutch packs withstands higher temperature and pressures than materials used in earlier generations of the transmission, and handles higher energy shifts for improved durability.
- An all-new constant velocity joint incorporates a double-roller design, which helps reduce ride "shudder," provides excellent isolation from vibration and offers improved reliability due to superior wear resistance.

ALL-WHEEL DRIVE: Versatrak

Versatrak all-wheel drive is available on the Montana SV6. The on-demand system is lightweight, quiet and efficient - and one of the segment's most advanced approaches to all-wheel drive. If one or both front wheels lose grip, the Versatrak system engages action progressively, with no buttons to push or levers to throw. It is always poised to help drivers make use of the traction available by not only transferring torque from front to rear, but also from side to side between the rear wheels - a capability not found in many other competitive systems.

CHASSIS SYSTEMS

With features such as a new world-class braking system and the first-time availability of StabiliTrak stability control system in a Pontiac van, the 2005 SV6 provides the kind of stopping capability and superior handling control expected of Pontiac's new performance vehicles.

Additionally, features like larger standard wheels and tires, a more rigid chassis structure, longer wheelbase and sport-tuned suspension upgrades increase stability and provide a smoother, more comfortable car-like ride.

The SV6 chassis systems are comprised of:

- Large 17-inch wheels and tires for more stable ride and handling.
- A specially tuned independent MacPherson strut front suspension, including a new four-point isolated, hydroformed engine cradle, tuned bushings and stabilizer bars on front-wheel-drive and all-wheel-drive models. Although designed primarily for structural safety improvements, a smoother, more quiet ride is an additional benefit of the stiff cradle.
- Proven twist-beam rear axle design with an integral stabilizer bar. The rear suspension trailing arms, which provide wheel control, load transfer and isolation, feature a new hydraulic bushing, which increases the damping ability of the bushing to provide a quieter, smoother ride.
- In addition to the base suspension packages, three optional suspension packages are available. They include an optional FE3 Sport Suspension, an FE4 Ride and Handling Package and FE5 Ride, Handling and Performance package.
- Variable-assist power steering for easier handling.
- Powerful four-wheel disc brakes, delivering shorter stopping distances, longer life, improved pedal feel and smoother, quieter operation.
- Standard Delphi 7.4 ABS Brake Control, providing fast response and superior wheel slip control on most road surfaces with low noise and minimal harshness.
- An optional Enhanced Traction Control System, which provides improved vehicle launch capabilities on all road surfaces.

The twist-beam rear axle and suspension system uses a pair of trailing arms, with a U-section cross beam and tubular stabilizer bar. A track bar runs from one side of the axle to an attachment on the body structure to provide a load path for lateral (cornering) forces. The rear suspension also includes standard 30 N/mm (Newtons-per-millimeter) coil springs, specifically tuned 30-mm self-leveling twin tube air shocks and a 34-mm stabilizer bar.

An optional automatic level control system adds an air bladder around each rear shock absorber to help the SV6 maintain a flat attitude when heavily loaded or towing. An accessory outlet, air hose, and pressure gauge are available to provide a handy means of inflating all types of sports gear and bicycle tires.

StabiliTrak

StabiliTrak, GM's advanced Vehicle Stability Enhancement System (VSES), is available for the first time on a Pontiac van. StabiliTrak greatly improves safety, stability and control on all road surfaces at all speeds. Its precise, all-weather control is particularly beneficial when driving on slick road surfaces or during emergency maneuvers, such as when a driver swerves to avoid an object on the road.

StabiliTrak maximizes handling, braking and acceleration dynamics by using a combination of systems, including stability enhancement, ABS and traction control. Sophisticated sensors continually monitor the driver's intended and actual vehicle path and makes adjustments accordingly. The system is always on, constantly measuring steering angle, wheel speed, brake pressure, lateral acceleration and yaw rate (vehicle rotation rate such as during cornering). StabiliTrak is automatically enabled - without the driver having to do anything - providing full stability, traction and ABS control whenever the van operates in forward gear.

In adverse conditions, if the van is understeering or oversteering, StabiliTrak quickly and precisely adjusts brake pressure at individual wheels to help the driver steer in the desired direction. The system also adjusts engine power via the electronic throttle control, as required, to help maintain vehicle stability and improve acceleration.

StabiliTrak is not available on vans equipped with the Versatrak AWD system.
 
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