GM Duramax Investment Presages Diesel Power for Suburban, Hummer
February 06, 2008

By Bill Visnic

General Motors Corp.’s announcement this week of a large investment to produce a new variant of its largest diesel engine, one that complies with emissions standards in all 50 states, likely foretells GM’s plan to use the engine for the Chevrolet Suburban SUV, in addition to other large SUVs, pickups and vans already using the current 6.6-liter Duramax diesel V8.

Currently, even the largest versions of the Suburban have made do with GM’s gasoline 6-liter V8. The gasoline-engine Suburban 2500’s 12 mpg city and 17 mpg highway fuel-economy ratings appear to be an increasing liability, however — a liability diesel power could help to alleviate.

But there’s a new complication: Current federal Tier II emissions standards created a new category of vehicles — Medium Duty Passenger Vehicles, which, beginning in 2009, must meet the same emissions standards as every other passenger vehicle on the road.

The MDPV category snares vehicles — Suburban 2500, Hummer H2 and full-size passenger vans, to name a few — that used to thunder through a loophole that allowed vehicles of more than 8,500 lbs. gross vehicle weight rating (GVWR) to bypass emissions compliance.

It was long assumed vehicles of more than 8,500 lbs. GVWR (the combined weight of the vehicle and its maximum amount of passengers and cargo) were used for “work” or business purposes, but vehicles such as the largest Suburbans and the Hummer H2 (and former competitors such as Ford’s now-dead Excursion), which exceed the 8,500-lb. threshold, are primarily used for personal transportation.

Beginning in 2009 all “passenger” vehicles with GVWR between 8,500 lbs. and 10,000 lbs. are covered by the new MDPV classification, meaning they must comply with the same federal and California emissions standards as every other light-duty vehicle. Many of GM’s largest trucks and SUVs, which currently use the Duramax diesel, will be classified as MDPVs and face emissions compliance.

Thus GM’s announcement it is investing $69 million in the Duramax diesel engine plant in Moraine, Ohio, to produce the next generation of the engine that will allow vehicles it powers to meet light-vehicle emissions standards in all 50 states. The nationwide compliance is particularly difficult for diesels, which produce excess oxides of nitrogen (NOx) emissions. Many automakers planning to launch diesel-powered vehicles will use the same NOx-reducing system GM plans for the Duramax — so-called selective catalytic reduction, which injects a urea solution in the exhaust stream to cut NOx to levels acceptable to Tier II and California LEV 2.

The new emissions-compliant Duramax, coming in 2010, said GM, will be required in order to allow the company to continue selling its full-size passenger vans — which will be classified as MDPVs — in all 50 states, although the '09 model year could be skipped until the new Duramax is ready. Duramax-powered Chevrolet and GMC 2500HD pickups also would be 50-state legal, although those models may continue to be permitted to comply with less-stringent heavy-duty diesel emissions regulations if they are not deemed “passenger” vehicles.

Most important, however, the new Duramax would make possible diesel- powered variants of the largest Suburbans, as well as the Hummer H2, which currently has a GVWR of 8,600 lbs. — and diesel power could markedly improve these vehicles’ real-world fuel economy.

GM is working on an innovatively designed diesel V8 earmarked for light-duty vehicles, starting with its full-size pickups, in 2010, but that unit, at 4.5 liters, presumably would not be powerful enough for vehicles in the MDPV category. GM sources have insinuated the smaller 4.5-liter diesel, installed in a diesel-powered Suburban unveiled at SEMA last year, could be used in any number of trucks, SUVs and crossovers — even passenger cars — as it was designed to fit in the same space as today’s gasoline V8s.

Photos by GM

1 - GM Powertrain Vice President of Global Manufacturing John Buttermore, left, Ohio Lt. Gov. Lee Fisher, Ohio Governor Ted Strickland, DMAX HR Director Rod Kirkham and DMAX CEO Maho Mitsuya with the new Duramax 6.6-liter V8 turbo-diesel engine after GM announced its investment in Ohio to produce new diesel engines.

2 - Ohio Governor Ted Strickland comments on GM's announcement of a $69 million investment in the Moraine, Ohio, DMAX plant to manufacture new diesel engines. Seated in the rear are GM Powertrain Vice President Global Manufacturing John Buttermore, left, IUE President Jim Clark, DMAX CEO Maho Mitsuya and Congressman Mike Turner.

3 - GM's Suburbans would benefit from diesel power to improve their 12 mpg city and 17 mpg highway fuel economy, but would require the new diesel GM will produce in 2010 to meet 50-state emissions standards.

Posted by Michelle Krebs at 6:28 AM under Analysis , GM , Technology | Comments (3) | digg this | Seed Newsvine