B20 fuel is a blend of 20% biodiesel and 80% conventional diesel, which helps lower carbon-dioxide emissions and lessens dependence on petroleum. GM's new Duramax 6.6L turbo diesel engine has been 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. Reportedly, Chevrolet will unveil the 2011 Silverado heavy-duty trucks at the Chicago Auto Show on February 10.
Mike Robinson, vice president of Environment, Energy and Safety Policy at GM, said: "B20 capability in our new heavy-duty trucks is the latest addition to a growing number of alternate fuel options offered by General Motors. We are seeking different paths to fuel solutions in order to maximize efficiency, reduce emissions and minimize the dependence on petroleum.
"The 2007 federal energy bill mandates increased biodiesel production and more states and municipalities are requiring it. 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.
The company said that the 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.
Coleman Jones, biofuels implementation manager at GM, said: "True biodiesel is created through transesterfication and that's what the Duramax 6.6L is designed to use. 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."
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. The Duramax 6.6L's diesel particulate regeneration system features a downstream injector that supplies fuel for the regeneration process. This reduces potential oil dilution, important with using biodiesel. Downstream injection saves fuel and works better with B20 than in-cylinder post injection.