Addressing the demands of increasingly competitive automotive markets, General Motors Powertrain launches an all-new family of modular V6 engines that incorporates state-of-the-art features and technology in a package that delivers high performance and refinement.

The new global V6 engine family was created to fulfill GM’s strategy to build a new generation of sophisticated V6 engines for global application in premium and high-performance vehicles. The global V6 engine was designed from a clean sheet of paper to assure multiple displacement, configuration and content possibilities, making it remarkably versatile, yet buildable, in a common manufacturing environment that promotes high levels of quality and tolerance control.

The global V6 engine is the first V6 engine program to address what Thomas G. Stephens, group vice president, GM Powertrain, says is a vital initiative: to develop world-class engines with fully contemporary features -- such as dual overhead cams and variable valve timing -- but at a competitive cost structure that allows use of the engines in a global mix of vehicles. This is the heart of the "high feature" philosophy.

Conceived for Flexibility

From the global V6 engine program start in February 1999, a prime objective was to develop a highly flexible "platform" from which a matrix of possible variants could be developed. The new V6 was designed for true global duty: future variants will power a variety of vehicles worldwide.

Several components and features will be common to all global V6 family engines, however, reflecting the high feature strategy to provide high levels of performance, technology and refinement, combined with the reliability and cost-effectiveness for which GM Powertrain is world-renowned. All global V6 engines will employ:

- All-aluminum construction 
- Dual overhead camshaft (DOHC) 
- 4-valve-per-cylinder valvetrain 
- Roller-finger follower valvetrain 
- Continuously variable cam phasing 
- Electronic throttle control (ETC) 
- Durable forged-steel crankshaft 
- Piston-cooling oil jets 
- Coolant-loss protection software 
- GM’s Oil Life System 
- 32 bit microprocessor 
- Coil-on-plug ignition 

"Since the start the global V6 project team was determined to introduce a V6 engine superior to all in the industry, and in record time," said Tim Cyrus global V6 chief engineer. "The team tapped GM’s vast technical expertise an developed a V6 with industry leading reliability, flexibility, package size, pleasibility, efficiency and value. This engine was developed by a unique team with talented members from across each of the global GM engine departments and suppliers We have delivered an engine that can be easily integrated into most platforms, has industry leading NVH and performance with three discrete combustion systems MPFI, SIDI and turbo."

The global engine family encompasses a range of displacements. In addition to the 3.6L variant that marks the launch of the new engine in production vehicles, there also are 2.8L and 3.2L variants. Engine displacement can be expanded to 3.8L, or as large as 4.0L when the cylinder liners are eliminated in favor of special cylinder bore coatings. Smaller-displacement global engine variants are particularly crucial in world markets where market conditions and competitive issues demand high performance from smaller engines. 

- Whatever the displacement, the global V6 engine family promises high specific power and torque competitive with the best contemporary V6 engines. The wide range of potential global V6 engine displacements and configurations allows power and torque output perfectly suited to a variety of vehicle, platform, drive configuration or market requirements. The global V6 engine family will effortlessly produce power ranging from approximately 200 hp to more than 370 hp; torque output will run from 200 lb-ft to in-excess of 350 lb-ft.

- In addition to a wide range of displacements, the basic global V6 engine architecture was designed to support a host of feature and "content" options, establishing a broad matrix of potential engine configurations. Aside from the normally aspirated/sequential port fuel injection "foundation" architecture, possible major variants include: 

A spark-ignition direct-injection (SIDI) V6 of either 2.8L or 3.2L displacementd. Gasoline direct injection is a technology that can produce fuel-economy gains on the order of 10 percent, with no loss of performance. To be most responsive to regulatory and other market considerations, the global V6 engine design has provisions for both stratified-charge (lean-burn) and stoichiometric-charge SIDI architectures. SIDI engines are rapidly expanding in Europe and other regions with high fuel costs. 

Turbocharged engines of either 2.8L or 3.2L, with a variety of power and torque outputs depending on specific content. Turbocharging remains one of the best strategies to increase power and torque without increasing engine size. 

- Finally, with its global design priority, the new V6 was developed from the beginning to be easily configured to power an array of platforms, drive orientations and future-technology adaptations. By starting with a totally new architecture, engineers were free to anticipate many divergent uses for the global V6 and design it for the exceptional flexibility, avoiding the problems that arise when a powertrain designed for a relatively limited purpose must be adapted for a different vehicle architecture or drive layout. 

From the start, the global V6 engine was designed to power:

- Front-wheel drive (FWD) platforms, in which the engine typically is situated transversely. 
- Rear-wheel drive (RWD) vehicles and platforms, where the engine typically is longitudinally mounted. 
- All-wheel drive (AWD) architectures, which can dictate either transverse or longitudinal mounting. 

The global V6 engine is also suitable for parallel-hybrid application. Parallel hybrid vehicles employ a standard gasoline engine and an electric motor or motors, either or both of which can propel the vehicle. Hybrid vehicles offer the prospect of greater fuel economy and can deliver other emissions- and fuel-reduction possibilities. 

the 3.6-litre Global V6 engine

The 2004 3.6L global V6 engine is the first variant of the global V6 engine family to go into production. Although a design priority was to minimize or even eliminate all sources of undesirable engine noise, the sound that does reach the vehicle occupants has been carefully optimized to be rich and rewarding.

Intense focus on reducing noise, vibration and harshness (NVH) did not compromise the dictates of high specific output. The 3.6L global V6 develops:

- 260 hp @ 6,500 rpm 
- 250 lb-ft of torque @ 2,500 rpm 

The adoption of fully variable valve timing for both intake and exhaust valves – a first for any GM engine – provides outstanding flexibility, fuel economy and emissions-reduction. The four-cam variable valve timing is a key element in the global V6’s control strategy, which imparts the engine with extreme flexibility. For example, 90 percent of the 3.6L V6’s peak torque is available across a remarkably broad operating range: from 1,600 rpm to 5,800 rpm.

"Flexibility was very important," says Bob Jacques base engine design system engineer. "We insisted on going after high performance and high refinement at the same time."

Compared to an existing GM DOHC V6, the global 3.6L V6 develops 20 percent more peak power, a 13 percent increase in peak torque – and a 24 percent increase in torque-integral, or the amount of torque available at most points throughout the rpm range.

Flexibility & Power Optimization

High feature technology is the essence of GM Powertrain’s philosophy behind the global V6 engine family. This consists of a combination of technologies that allow the new V6 engine to squeeze the most power from the least amount of fuel, while producing low emissions.

Key technologies:

- A four-cam continuously variable cam phasing system. This electronically controlled, hydraulically actuated system places a "phaser" on each of the global V6’s four camshafts. The cam phasers enable the rotating of each camshaft relative to the crankshaft, eliminating the "fixed" camshaft positions of most engines. 

Typically, fixed camshafts dictate valve openings that are a compromise between the desire to have the engine idle smoothly, produce good low-rpm torque, and high-rpm power. The global V6 engine cam phasers, which allow intake cam adjustment through 50 degrees of crankshaft rotation and 50 degrees for exhaust-cam adjustment, permit variability of valve timing to accommodate the often-divergent needs for power, driveability, economy and least emissions.

In addition to enhancing power and torque and increasing fuel efficiency, the cam phasing system allowed engineers to eliminate the exhaust gas recirculation (EGR) system typical to most modern engines. By closing exhaust valves later than normal, the cam phasing system forces the desired amount of exhaust gas back into the combustion chamber for more complete burning in the next combustion cycle.

- A dual-stage variable intake manifold (VIM). The VIM incorporates a switch in the manifold that changes the plenum volume available for resonance tuning of the inlet flow path. When the VIM switch is shut, the cylinders feed from two separate plenums. In this mode the system boosts cylinder charging in the low to mid speed range. At higher engine speeds, the VIM switch opens and the cylinders all feed from a common larger plenum which boosts cylinder charging at high engine speed. 

- An electronically controlled throttle (ETC) effectively coordinates the driver’s intentions with the actions of the various control components. ETC eliminates the traditional cable between the accelerator pedal and the throttle body. A throttle position sensor registers the degree to which the driver is depressing the accelerator pedal and translates that movement to a stepper motor that moves the throttle. By eliminating the mechanical connection between the accelerator pedal and the engine, throttle opening can be controlled with advantageous precision. 

- Micro-hybrid engine control unit ECU. The global V6 ECU represents the latest in engine-management hardware, as well as the software that dictates every aspect of engine operation. The micro-hybrid design embeds all of the necessary electronic circuitry on a four-layer "sandwich" substrate that drastically reduces the size of the control unit. Moreover, the micro-hybrid design imparts a new level of robustness that allows the ECU to be engine-mounted, despite the high levels of vibration the unit experiences from its engine mounting. 

The micro-hybrid ECU can withstand mounting temperatures of 230 degrees Farenheit and vibration up to 30 g. The engine mounting frees valuable space in the vehicle underhood area and eliminates attachment problems at the assembly plant. The 32-bit capacity of the micro-hybrid ECU is the most powerful currently used for automotive application

- Torque-based engine control strategy. Engine output for the driver’s desired throttle opening is determined by the micro-hybrid ECU. The torque-based strategy calculates optimal throttle position, variable intake manifold position, continuously variable cam phasing positions and various other operational inputs and then translates that information into an ideal throttle position. 

The torque-based engine control strategy is superior to early electronically controlled throttle-based engine-management systems that relied only on the throttle position sensor to govern throttle opening.

- Returnless fuel system. The returnless fuel system architecture eliminates fuel system recirculation thereby reducing fuel heating and evaporative emissions. A variable pressure option is used on the turbo engines. A pressure sensor located in the fuel rail provides feedback to a variable pressure fuel pump in the fuel tank. Fuel control, emissions, and driveability are significantly improved by increasing the operating fuel pressure at higher engine loads to deliver the required fuel flow but maintain precise fuel control at lower engine loads with injectors sized for optimal refinement. 

The global V6 engine’s advanced micro-hybrid ECU represents the first use of the technology for a North America-sourced engine, says John Rydzewski Global V6 Lead Control System engineer . The high feature content and torque based engine control and three combustion system (MPFI, SIDI and turbo) make this one of the most sophisticated control systems in the market.

Superior Refinement, Durability

Although outstanding power and flexibility were of utmost importance, no stone was unturned when it was time to set the goals for global V6 refinement and NVH attributes.

"We went after all the benchmarks," says Jaucques. "You name it – if there is a good V6 out there, we found out how and why it was good."

Numerous design features were incorporated to ensure the global V6 engine is one of the most polished V6s available throughout the world:

- Specially isolated cam covers incorporate an isolated gasket around the cover perimeter and radial lip seals at the tubes through which each spark is inserted. These components decouple the cam cover from vibration created by the combustion process. 
- The structural aluminum oil pan is attached by a full-circle mounting that enhances bending stiffness. Specially contrived curves on the major panel surfaces and the pan’s sidewalls mitigate "drumming" from the oil pan. 
- The pressure-actuated piston-oil jets – a feature often found on costly, high-performance engines – not only help to cool the pistons to achieve high power and increased durability. The extra oil layer on the cylinder bores and reciprocating components such as the piston wristpin minimizes noise that typically emanates from these components. 
- The engine front cover has internal damping plates that quell vibrations caused by the engine. The steel plates, made in two different thicknesses "tune" at differing frequency from the aluminum front cover; the frequency separation dampens noise output. 
- "Hiss" from the PCV valve – virtually inaudible amongst other engine-generated noise – is nonetheless eliminated through the simple expedient solution of using two dissimilar-sized flow-metering holes instead of a single hole. 
- The equal-length intake manifold runners minimize half-order noise content. "Those events are associated with ‘thrashy’ sounds," says Rydzewski. "We specified a symmetrical intake-flow path for each cylinder bank. If you want refinement, regardless of where you’re looking to improve, you want symmetry, you want consistency." 
- Polymer coating on the piston skirts helps the piston to track more smoothly and quietly in the bore. 
- A new oil pump design, the product of a highly specialized analysis of pump flow, prevents noise caused oil aeration. Tapered relief ports and a bypass baffle prevent pump pressure oscillations that lead to relief-valve "buzz." 
- The crankshaft sprocket employs durable, molded-rubber "cushion rings" that absorb the noise of the camshaft drive chain engaging the sprocket teeth. 
- The fuel rail includes an internal fuel pressure damper, which attenuates the pressure pulsation in the fuel system to reduce radiated noise. 

Design Details That Make a Difference

Component optimization for the global V6 engine family means that every engine has attention to detail that is a byword of GM Powertrain engineering.

- A forged steel crankshaft ensures the durability required of high specific output variants and provides an extra degree of robustness. 
- Flexible oil pan configurations facilitate the engines’s adaptability for all drive layouts. Global V6 engines destined for AWD applications, for example, are fitted with an oil pan cast specifically with a pass-through so that the front-wheel halfshaft can be fitted. 
- Three pressure-actuated piston-cooling oil-jet assemblies in the block each hold a pair of oil squirters that douse the underside of the piston and the surrounding cylinder wall with cooling oil. This practice reduces piston temperatures, which helps the engine develop more power. The cooler piston/cylinder interface also enhances longterm durability. 

Maths-Based Design

At the start of the global V6 engine development program, GM Powertrain engineers and associated technical sources created a "wish list" of engine attributes. That was followed by an intense process of prioritizing those desired attributes in relation to the realities of engineering, cost and manufacturing constraints. 

As each system or component was specified or redefined, the actual engine design also changed. This impossibly complex matrix of design elements was managed in a computerized, math-based design environment. The process significantly reduces development times while simultaneously cutting – or even eliminating – the need for physical testing, component analysis and engine simulation.

High Performance Transmissions

Global V6 engine variants will be backed by compact and efficient automatic transmissions, which employ a variety of advanced control technologies and features, as well as world-class manual transmissions. 

The engines are slated for front-wheel and rear-wheel drive applications, and will also be employed in all-wheel drive platforms.

Manufacturing Sites

The global V6 engine family will be assembled for all global applications at GM Powertrain facilities in St. Catharines, Ontario, Canada and Port Melbourne, Victoria, Australia.