General Motor’s 2011 heavy-duty diesel pickups will feature B-20 biodiesel capability. The alternative fuel is a blend of 20-percent biodiesel and 80-percent conventional diesel, which helps lower carbon dioxide emissions and lessens dependence on petroleum, according to GM.

The revised Duramax 6.6L turbo-diesel engine meets strict new emissions standards effective this year. It will power the redesigned 2011 Chevrolet Silverado and GMC Sierra heavy-duty pickups, as well as the Chevrolet Express and GMC Savana full-size vans.

“B-20 capability in our new heavy-duty trucks is the latest addition to a growing number of alternate fuel options offered by GM,” said Mike Robinson, vice president, environment, energy, and safety policy for General Motors.

GM is currently seeking different paths to fuel solutions to maximize efficiency, reduce emissions, and minimize the dependence on petroleum, continued Robinson.

Fuel Validated & Approved

Extensive testing and validation was performed on the Duramax 6.6L, using B-20 that meets American Society for Testing and Materials (ASTM) International standard D7467, which covers biodiesel blends between B-6 and B-20.

“Strict testing and validation was performed to ensure the new engine is B-20-capable; however, approved biodiesel is the only way to guarantee engine performance and longevity,” said Coleman Jones, GM biofuels implementation manager.

To make the Duramax 6.6L and its fuel system compatible with B-20, GM upgraded seal and gasket materials to withstand biodiesel’s ester content and included an upgraded fuel filter that features a coalescing element. According to GM, the filter improves the separation of water that may be present in the fuel, because biodiesel can attract and absorb water. More powerful fuel circuit heating 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, reducing potential oil dilution.

Biodiesel Use to Grow

Biodiesel is a domestically produced, renewable fuel made primarily of plant matter — mostly soybean oil in the U.S. In pure form, biodiesel lowers carbon dioxide emissions, according to GM.

Estimates by the National Biodiesel Board (NBB) indicate about 700 million gallons of biodiesel 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 additional government mandates and the availability of approved vehicles, such as the 2011 Chevrolet Silverado and GMC Sierra heavy-duty trucks.

The new Duramax 6.6L is covered by GM’s 5-year/100,000 mile powertrain warranty.