- The Washington Times - Friday, November 1, 2002

Stung by criticism of its powertrains from auto writers in general, and buff-book writers in particular, GM recently introduced most of its future powertrain products and technologies.
A recent show-and-tell previewed what GM will do in the future. At an October international media briefing at GM's proving grounds, Tom Stephens (group vice president, GM Powertrain) and Ned McClurg (vice president and general manager Powertrain Engineer Operations) introduvced: a 500-horsepower V-12, a new global family of so-called "hi-feature" V-6 engines, improved "hi-value" OHV V-6 engines, more applications of Displacement-on- Demand (or DOD), and a number of other transmission and powertrain technologies.
All aim to fulfill GM's product strategy, which is composed of: image, high-feature and high-value powertrains. The first, image, is less than 1 percent of the mix and includes powertrains that make people want to buy a vehicle: for example, the 5.7-liter V-8 in the Corvette Z06 one that produces 405 horsepower and a 0-60 mph time of less than 4 seconds.
The second group, high-feature, includes powertrains that have features such as dual overhead cams, four valves per cylinder and variable induction timing, among others. A perfect example is the 4200 in-line six, with its all-aluminum block and head that delivers V-8-like power 275 horsepower with the fuel economy of a six.
The third group, which makes up the majority of U.S. market at between 70 percent and 80 percent, is high-value powertrains. According to GM market research, high-value buyers want performance, fuel economy, low levels of noise and vibration, but are not concerned about how they get those benefits and their expectations must be satisfied in the most cost-effective way.
At the top of GM's performance pyramid are the image engines. Coming in the not-too-distant future is an all-aluminum, dual-overhead-cam, 48-valve, high-performance V-12. Displacing 7.5 liters, it will produce more than 500 horsepower in a package about the size of a big V-8 engine.
According to Tom Stephens, the new family of all-aluminum, 24-valve, DOHC V-6s is intended to satisfy powertrain requirements for premium and high-performance vehicles across the world's automotive markets. They will range in size from 2.8 to 3.8 liters and will feature hi-tech features such as roller followers, electronic throttle control, coolant loss protection software, oil-life monitoring, coil-on-plug ignition, and iridium spark plugs. First to be produced will be a 255-horsepower 3.6-liter version, making use of variable intake and exhaust valve timing for maximum low-end torque and high-end power.
In the largest segment of the market, the upgraded OHV V-6 family expands to include engines from 2.5 to 3.9 liters. Showing up first will be a 240-horsepower, 3.5-liter version in the 2004 Malibu.
Mr. Stevens makes no excuses for GM's powertrain strategy. In response to media criticism about GM's adherence to so-called "old" OHV engines, Mr. Stevens said they should be thinking "good versus bad," rather than "old versus new."
"Since the vast majority of customers don't care about features, we can do larger displacements with better performance and fuel economy at lower cost than our competitors. An engine's level of technology is defined by much more than its valve train, and efficiency levels of new pushrod engines come very close to those of OHC. Another advantage is packaging, and you can get modern OHVs to rev like DOHC engines. No one would call today's Corvette engine 'low-revving,'" he said.
Looking a bit further down the road, another major advantage is fuel-saving cylinder deactivation. Displacement-on-Demand deactivates half of the cylinders by closing both intake and exhaust valves under light load.


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