GM Demonstrates Future Technologies to Improve Future Powertrain Efficiency

MILFORD, Mich. – General Motors today demonstrated to automotive journalists a host of advanced powertrain technologies it is developing to both reduce emissions and improve the efficiency and performance of its internal combustion engines, automatic transmissions and hybrid systems.

The company also revealed technical details on several new products scheduled to debut in 2006, including new variants in the Gen IV small-block V-8 engine family; six-speed automatic transmissions; and the hybrid system for the 2007 Saturn VUE Green Line, the latest model in GM’s broad hybrid portfolio.

The new powertrains are part of GM’s goal to roll out 50 new, more efficient and powerful engines and transmissions by the end of the decade – a plan GM Powertrain Group Vice President Tom Stephens revealed in September 2004.

“The continued refinement, advancement and application of internal combustion engine and transmission technology, as well as the rollout of hybrids, are part of GM's advanced propulsion technology strategy,” said Stephens. “Through these advancements, GM continues to reduce emissions and improve fuel economy as the company marches toward the long-term goal of producing hydrogen fuel cell-powered vehicles to remove the vehicle from the environmental debate.”

Technological progress enables advanced combustion concepts
As part of his presentation, Stephens said that many of the technologies under development today will enable GM to produce engines featuring advanced combustion systems like Homogeneous Charge Compression Ignition, or HCCI.

On Aug. 16, GM announced an initiative with Bosch and Stanford University researchers to accelerate the development of HCCI. GM officials also announced a goal to develop and demonstrate the viability of a HCCI engine concept within the next few years.

HCCI is a combustion technology that uses compression ignition rather than spark ignition to initiate the combustion process, resulting in higher efficiency and lower NO x emissions compared to a normal spark-ignition or diesel engine.

While the joint program will focus on the controls, sensors and actuators necessary to facilitate the combustion system, GM Powertrain engineers are developing the engine technology necessary to accommodate the advancements and make HCCI commercially viable.

“The technologies we are developing today – gasoline direct injection, Displacement On Demand, variable valve actuation and variable valve timing – all deliver incremental improvements to engine efficiency,” said Stephens. “But more importantly, they are the building blocks to mass-producing engines that can operate with advanced combustion systems like HCCI.”

New engines benefit from advanced technologies today
While many of the advanced technologies demonstrated to journalists were for future, unspecified powertrains, the new powertrains GM is launching today benefit from fuel-saving and performance enhancing features, like Displacement On Demand and variable valve timing.

“The new variants of Gem IV small-block V-8 are a perfect example of applying advanced, fuel saving technology to a high-volume of powertrains today,” said Stephens.

Multiple variants of the new small-block engines feature Displacement On Demand, as well as variable valve timing (VVT). Displacement On Demand seamlessly alternates the engine between eight- and four-cylinder operation, improving engine efficiency by as much as 12 percent in some vehicles.

Variable valve timing optimizes engine performance by continuously adjusting intake and exhaust valve timing in relation to the crankshaft. The introduction of variable valve timing in these engines is the industry’s first application of VVT on a mass-produced V-8 overhead valve engine.

Complete details of the new engine variants will be provided at a later date.

Six-speed automatics deliver improved efficiency, performance
In addition to improving engine efficiency, GM is launching a broad portfolio of advanced six-speed automatic transmissions to increase overall powertrain performance.

“During the next five years, GM will launch 10 new automatic six-speed transmission variants," said Stephens. "In fact, by 2010, GM will be producing more than three million six-speed transmissions per year."

GM six-speed automatic transmissions use a wide gear ratio spread to improve both performance and fuel economy over traditional four-speed automatics.

GM will launch seven of the six-speed automatic variants in North America and Europe . These include rear-wheel variants of the new Hydra-Matic six-speed, which debuted with the Hydra-Matic 6L80 in the 2006 Chevrolet Corvette and Cadillac STS-V and XLR-V. Also included in the new rear-wheel drive six-speeds is a new Allison 1000 six-speed, introduced in the 2006 Chevrolet Silverado HD and GMC Sierra HD pickups.

Rounding out the seven variants is the new front-wheel drive (FWD) Hydra-Matic 6T70 six-speed automatic transmission. The 6T70 is one of the industry’s most advanced FWD six-speed transmissions and is scheduled to debut in the all-new 2007 Saturn Aura midsize sedan.

Innovative hybrid systems enhance vehicle efficiency, provide broad consumer choice
In addition to improving the efficiency of conventional engines and transmissions, GM is in the midst of rolling out three innovative hybrid powertrain systems. The company plans to integrate the systems in up to 12 vehicle models, providing consumers a broad portfolio of hybrid systems that will vary in fuel economy savings and cost.

GM currently produces hybrid technology for diesel transit buses – 364 of which are on the road in 25 cities around the United States . The company also produces the Silverado and Sierra hybrid trucks – the world's first full-size hybrid pickup trucks.

According to Stephens, General Motors is now gearing up to launch the belt alternator starter system, an affordable hybrid system that will deliver good fuel economy savings. Saturn will be the first to debut the system, in mid-2006, when the 2007 Vue Green Line is introduced.

"The refinements GM is making to internal combustion engines and automatic transmissions today provides added efficiency benefits to GM's future hybrid powertrains,” he said. “With GM’s hybrid system in the Saturn Vue Green Line we expect consumers to get a real payback on their initial investment over the life of the vehicle.”

GM has also announced that it is co-developing an all-new, uniquely compact and scalable two-mode full hybrid drive system with DaimlerChrysler. This new two-mode full hybrid will initially launch in GM’s new Chevrolet Tahoe and GMC Yukon SUVs in 2007.

"Through the last 30 years in North America, we've improved our gasoline car fuel economy by as much as 130 percent and our gasoline truck fuel economy by as much as 75 percent," said Stephens. "We'll continue this trend of significant improvements by applying these and other engine and transmission technologies around the globe."

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and the hybrid system for the 2007 Saturn VUE Green Line, the latest model in GM’s broad hybrid portfolio.