GM's new Duramax 6.6L turbo diesel engine has been substantially revised to include B20 capability, as well as meet strict new emissions standards effective this year. The new Duramax will power the redesigned 2011 Chevy Silverado and GMC Sierra heavy-duty pickups, as well as the Chevrolet Express and GMC Savana full-size vans. Chevrolet will unveil the 2011 Silverado heavy-duty trucks at the Chicago Auto Show on Feb. 10.
"B20 capability in our new heavy-duty trucks is the latest addition to a growing number of alternate fuel options offered by General Motors," said Mike Robinson, vice president, Environment, Energy and Safety Policy. "We are seeking different paths to fuel solutions in order to maximize efficiency, reduce emissions and minimize the dependence on petroleum."
GM already leads in the marketing of FlexFuel vehicles capable of running on E85 ethanol with more than 4 million vehicles on the road today. Like ethanol, biodiesel is a domestically produced, renewable fuel made primarily of plant matter – mostly soybean oil. In pure form, biodiesel lowers carbon dioxide emissions.
"The 2007 federal energy bill mandates increased biodiesel production and more states and municipalities are requiring it," said Robinson. "Biodiesel production is growing and GM is excited and ready to satisfy demand with our new B20 capable Duramax 6.6L engine."
Estimates by National Biodiesel Board indicate about 700 million gallons of the fuel were produced in 2008 – up from about 500,000 gallons in 1999. Market fluctuations caused production to decrease in 2009, but it is expected to rise with more mandates and the availability of approved vehicles, such as the 2011 Chevrolet Silverado and GMC Sierra heavy-duty trucks.
Validated and approved fuel
Extensive testing and validation was performed on the Duramax 6.6L using B20 that meets ASTM International's standard D7467, which covers biodiesel blends between B6 and B20.
"True biodiesel is created through transesterfication and that's what the Duramax 6.6L is designed to use," said Coleman Jones, GM biofuels implementation manager. "Strict testing and validation was performed to ensure the new engine is B20-capable, however approved biodiesel is the only way to guarantee engine performance and longevity."
The Duramax diesel is covered by GM's five-year/100,000 mile powertrain warranty.
To make the Duramax 6.6L and its fuel system compatible with B20, GM upgraded some seals and gasket materials to withstand the ester content of biodiesel and included an upgraded fuel filter that includes a coalescing element. It improves the separation of water that may be present in the fuel, because biodiesel can attract and absorb water. Also, additional heating of the fuel circuit was added to reduce the chance of fuel gelling or waxing that could plug filters.
The Duramax 6.6L's diesel particulate regeneration system features a downstream injector that supplies fuel for the regeneration process. This greatly reduces potential oil dilution, important with using biodiesel. Downstream injection saves fuel and works better with B20 than in-cylinder post injection.
About General Motors
General Motors, one of the world's largest automakers, traces its roots back to 1908. With its global headquarters in Detroit, GM employs 204,000 people in every major region of the world and does business in some 140 countries. GM and its strategic partners produce cars and trucks in 34 countries, and sell and service these vehicles through the following brands: Buick, Cadillac, Chevrolet, GMC, GM Daewoo, Holden, Opel, Vauxhall and Wuling. GM's largest national market is the United States, followed by China, Brazil, Germany, the United Kingdom, Canada, and Italy. GM's OnStar subsidiary is the industry leader in vehicle safety, security and information services. General Motors acquired operations from General Motors Corporation on July 10, 2009, and references to prior periods in this and other press materials refer to operations of the old General Motors Corporation. More information on the new General Motors can be found at www.gm.com.
SOURCE General Motors
National Biodiesel Conference
Chicago Auto Show
Kelly Wysocki, GM Environmental Communications
Tom Read, GM Technology Communications, Powertrain
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