Development of Cancelled GM Diesel Was Complete

Development of Cancelled GM Diesel Was Complete

By Bill Visnic

DETROIT - General Motors Corp. caused a stir when it confirmed yesterday that it is shelving an innovatively designed diesel engine that was earmarked to provide something of a fuel-efficiency revolution for its light-duty pickup trucks and possibly its full-size SUVs.

The Duramax 4.5-liter V8 diesel design "was complete," according to a GM spokesperson, who added that GM engineers "were doing the vehicle engineering development work associated with integrating the diesel into the vehicle." GM had billed the Duramax as a 2010 engine and was set to begin building the engine at a longstanding powertrain manufacturing site in Tonawanda, New York.

One source in the powertrain sector said the Duramax diesel's innovative design -- among other things, exhaust exits in the inside "valley" of the vee engine, rather than through conventional exhaust ports that empty into manifolds on the outside of each cylinder bank -- could present unique packaging challenges to adapt it for the engine bay of an existing pickup, such as the Chevrolet Silverado or GMC Sierra, or a truck-based SUV like the Chevrolet Tahoe or GMC Yukon.

Each of the Detroit automakers had been adamant that smaller diesel engines for its half-ton pickups and pickup-based SUVs could achieve the same efficiencies - and popularity - that have made diesels a mainstay of their medium-duty pickup lineups. But the industry's deepening financial crisis and a relatively recent inversion of the price relationship between diesel fuel and gasoline has cratered their enthusiasm for the strategy.

The promise from diesels has been as much as a 25-percent hike in fuel economy compared with currentl light pickups powered by gasoline V8s.
 
But from the onset, the proposed new light-truck diesels - Ford Motor Co. has an in-house design and Chrysler LLC had been working with longtime diesel supplier Cummins Inc. -  were saddled with a thorny business case in part because of the expensive exhaust after-treatment systems the engines need to comply with tougher new nationwide emissions standards. In the medium-duty pickup market, the diesel engine option typically adds $5,000 or more to the vehicle price, and those engines aren't required to use most of the pricey after-treatment components necessary for diesel-powered light-duty models.

The GM spokesperson said the company is open to joint-venture manufacturing possibilities for the 4.5-liter Duramax, saying GM remains optimistic that the unique diesel may yet see the light of day.

"We are willing to partner with a third party on the diesel as long as it is a win-win for us. We won't confirm any discussions (with potential JV partners)," the spokesperson said in an e-mail to AutoObserver.

"Bottom line, we want to build this diesel," the spokesperson said.

"This decision to indefinitely postpone the diesel was driven by a very tough economic climate for us as well as capital constraints. We recognize the enthusiasm for this diesel with our Chevy/GMC customers and how greatly disappointed they are with this news. The same is true within our powertrain engineering and manufacturing team and the entire company. We are optimistic that we will still be able to add it back into our portfolio."

Photo by GM

GM's now-postponed Duramax 4.5-liter V8 turbodiesel fronts revolutionary design features.

Michelle Krebs:  is Editor-in-Chief of AutoObserver.com. Follow @AutoObserver on Twitter.