MILAN, Mich. - Large diesel pickups are an American phenomenon, but General Motors' new Dura-max Diesel V-8 was born in Japan.
GM relied on its Japanese partner, Isuzu Motors Ltd., to design and develop the new diesel for heavy-duty versions of the 2001 Chevrolet Silverado and GMC Sierra.
The technology-packed 6.6-liter V-8 engine, being shown to reporters at a drag strip here, finally gives GM a worthy competitor to the popular Power Stroke diesels sold by Ford Motor Co.
The diesel segment is increasingly important to GM's heavy-duty pickup business. Diesels have grown from 25 percent of the market in 1989 to 50 percent this year, said Edward Koerner, executive director of chassis and powertrain at GM's Truck Group.
'In this segment, having the right powertrain is absolutely key,' he said. He acknowledged Ford's Power Stroke for F-250 and F-350 pickups is now the industry benchmark.
Koerner would not disclose the Duramax's horsepower or torque ratings. Its new five-speed automatic transmission from GM's Allison Transmission division can handle up to 375 hp and 545 pounds-feet of torque.
The Duramax will replace GM's current 6.5-liter turbodiesel, which makes 195 hp and 430 pounds-feet of torque. The Duramax will be assembled by a GM-Isuzu joint venture called DMAX Ltd. in a new plant in Moraine, Ohio, starting next January.
Soon after, heavy-duty Silverados and Sierras, including 2500, 3500, and 3600 Series with Crew Cab, Big Dooley and Chassis Cab variants, will begin rolling off the line in Flint, Mich. GM did not announce pricing.
Like the Power Stroke, the Duramax is a 90-degree turbo-charged V-8 with direct injection and a cast-iron block. However, most of the similarities end there.
The Duramax has aluminum cylinder heads for weight savings and better heat dissipation. It is a feature that is not found on the Power Stroke and that GM has avoided on its gasoline light-truck engines. Surveys say truck buyers worry about aluminum's durability, GM says.
But the Duramax's heads prove aluminum can handle even the higher compression ratios of diesels, said Jim Kerekes, chief engineer of diesel engines for GM Powertrain.
The Duramax also has four valves per cylinder for better breathing.
The Duramax uses a common rail fuel injection system from Robert Bosch GmbH. Fuel is delivered to the cylinders via a high strength line at pressures up to 23,000 pounds per square inch. The high pressures allow better atomization of the fuel for cleaner burning.
GM announced last year that it will farm out future diesel work to Isuzu. Working with the Japanese truckmaker during the three-year Duramax program exposed GM's engineers to a new corporate culture, said Koerner.
'We are bridled by a culture, to a certain extent, where folks like to move about through the organization to reach upper levels of management,' he said. '(Isuzu) seems to be more founded in rewarding expertise and stability.'
Koerner recalls one young Isuzu engineer who already had amassed 10 years of experience calibrating diesel fuel systems.
'It became clear early on that they really are experts in diesels.'