GM Adds New 2.8L V-6 VVT Variant to Global V-6 Engine Family

New Engine to Debut in 2005 Cadillac CTS

DETROIT July 29, 2004; Created to fulfill GM's strategy calling for sophisticated V-6 engines for global application, GM has developed the all-new 2.8L V-6 VVT engine - the second variant in GM's new global V-6 engine family. The new 2.8L, based on the 3.6L V-6 VVT that debuted in the 2004 Cadillac CTS, will serve as the new base engine in the 2005 CTS.

The global V-6 engine family is the first GM V-6 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.

The 2.8L V-6 VVT engine Using the same design principles that went into the popular 3.6L V-6 VVT, the 2005 2.8L V-6 VVT engine is the second variant of the global V-6 engine family to go into production. Like its larger counterpart, one of the primary design priorities was to minimize or even eliminate all sources of undesirable engine noise, while ensuring that the 2.8L engine sound that does reach the vehicle occupants has been carefully optimized to be rich and rewarding.

Intense focus on controlling noise, vibration and harshness (NVH) did not compromise the dictates of high specific output. The 2.8L global V-6 develops 210 hp at 6500 rpm and 194 lb.-ft. of torque at 3300 rpm, generating more base power than the standard engines in many comparable European luxury sport sedans. The adoption of fully variable valve timing for both intake and exhaust valves is a key element in the V-6 VVT control strategy and provides performance, fuel economy and reduced emissions.

"Flexibility was very important," said Tim Cyrus, global V-6 chief engineer. "We insisted on going after high performance and high refinement at the same time."

Flexibility and power optimization High feature technology is the essence of GM Powertrain's philosophy behind the global V-6 engine family. This consists of a combination of technologies that allow the new V-6 engine to squeeze the most power from the least amount of fuel, while producing low emissions.

And though the new 2.8L uses a high 10:1 compression ratio, regular unleaded is recommended, reducing owner's annual fuel costs by several hundred dollars per year compared to many competitors' premium-only V-6s.

Key technologies include: all-aluminum construction, dual overhead camshafts (DOHC), four-valves-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 and coil-on-plug ignition.

Superior refinement, durability Although power and flexibility were of utmost importance, no stone was unturned when it was time to set the goals for V-6 refinement and NVH attributes.

"We went after all the benchmarks," says Cyrus. "You name it - if there is a good V-6 out there, we found out how and why it was good. And then we improved upon it."

Numerous design features were incorporated to ensure the global V-6 engines are among the most polished V-6s available throughout the world.

The 2.8L V-6 VVT employs specially isolated cam covers to decouple them from vibration created by the combustion process, while the engine front cover incorporates internal damping plates to quell engine vibrations. A structural aluminum oil pan, attached by a full-circle mounting, enhances bending stiffness and mitigates "drumming" from the oil pan.

Polymer-coated piston skirts help the piston to track more smoothly and quietly in the bore. Pressure-actuated piston-oil squirters help cool the pistons, contributing to performance and durability, and help minimize noise that typically emanates from the cylinder bores and reciprocating components. "Hiss" from the PCV valve is eliminated by using two dissimilar-sized flow-metering holes, while equal-length intake manifold runners minimize half-order noise content.

A new oil pump design prevents noise caused by oil aeration while 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 V-6 family means that each engine receives 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 engine's adaptability for all drive layouts. V-6 VVT engines destined for AWD applications, for example, are fitted with an oil pan cast specifically with a pass-through so that the front-wheel half-shaft can be fitted.

Three pressure-actuated piston-cooling oil-squirter 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 long-term durability.

A global engine family The global engine family was designed to encompass a range of displacements to meet market requirements around the world. In addition to the 2.8L and 3.6L variants, the family was designed to include 3.2L and 3.8L engines.

Whatever the displacement, the global V-6 engine family promises high specific power and torque competitive with the best contemporary V-6 engines. The wide range of potential global V-6 engine displacements and configurations allows power and torque output perfectly suited to a variety of vehicle, platform, drive configuration or market requirements. The global V-6 engine family will effortlessly produce power ranging from approximately 200 hp to more than 370 hp; torque output will run to as much as 350 lb.-ft.

In addition to a wide range of displacements, the basic global V-6 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 spark-ignition direct-injection (SIDI) and turbocharged engines

Finally, with its global design priority, the new V-6 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 V-6 and design it for 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 V-6 engine was designed to power front-wheel-drive (FWD), rear-wheel-drive (RWD) and all-wheel-drive (AWD) platforms.

The first variant, the 3.6L V-6 VVT, debuted in the 2004 Cadillac CTS, and was available in the 2004 Cadillac SRX and 2004 Buick Rendezvous.

For 2005, the 3.6L V-6 VVT will be used in a number of additional applications around the world, including the new 2005 Cadillac STS and 2005 Buick LaCrosse.

The global V-6 engine family is built at GM Powertrain's St. Catharines engine plant and Holden's Port Melbourne facility. The 2.8L V-6 VVT (LP1) for Cadillac will be built at the engine plant in St. Catharines.