DETROIT -- General Motors plans a series of expensive changes to its Duramax V-8 engine to cope with tough U.S. diesel emission rules taking effect Jan. 1.
GM says reworking the 6.6-liter diesel, which powers heavy-duty versions of the Chevrolet Silverado and GMC Sierra pickups, won't interrupt production. But the modifications are expected to sharply increase the cost of building the engine.
Heavy-duty trucks with a gross vehicle weight rating of as much as 10,000 pounds must meet the Tier 2 Bin 5 emissions standards. The new rules call for a 90 percent reduction of oxides of nitrogen, or NOx, and particulate matter, or soot.
GM will significantly revamp the emissions system of the Duramax, which also is used in full-sized vans and commercial vehicles. GM Powertrain spokeswoman Susan Garavaglia said the diesel will meet the 2007 regulations with:
- A new variable geometry turbocharger.
- Enhanced exhaust gas recirculation.
- Closed crankcase ventilation system.
- Changes to the exhaust system that include an oxidizing catalytic converter to clean NOx emissions and a particulate filter to lower soot.
Diesel particulate filters, first used in Europe in 2005 on Peugeot and Citroen vehicles, will land in America for the first time on diesel versions of the Mercedes-Benz E320 and the Jeep Grand Cherokee coming this fall.