One of several interesting little surprises to come out of this week's GM product technology showcase was the upgraded 6.6-liter Duramax V8. Unfortunately, the 4.5-liter diesel developed for the light duty applications remains on the shelf for now, but the big diesel is getting a significant revamp in 2010. First up is a new fuel injection system that takes advantage of the latest common rail technology with piezo electric injectors. The system now runs at 2,000 BAR (29,000 psi) and can do up to six injection pulses per cycle. This allows for more precise, slower and cooler combustion.
The lower combustion temperature reduces NOx production and the multiple pulses help reduce noise significantly. The 6.6-liter still uses a single variable vane turbocharger mounted on top of the intake manifold. Downstream, the engine also meets the latest emissions standards thanks to a diesel particulate filter and a urea injection SCR system. Read our drive impressions - and the news about biodiesel - after the jump.
[Source: General Motors]
The big surprise though was the revelation that the engine is now factory certified to run on B20 biodiesel blends. This is the first engine gain that status. GM is also making the engine B20 capable without needing any kind of fuel sensor.
We had a chance to sample a Chevy Express van equipped with the new engine and it is noticeably more refined than the previous edition. The engine is not quite on the same level as the latest passenger car diesels from Audi, BMW or Mercedes, but this is a work truck. Operation was smoke free and the engine proved very responsive right off the line. It's also very capable with a towing capacity of over 17,000 pounds. Heavy duty vehicles like this don't get official EPA ratings, but a GM engineer on hand said the van as equipped with a 6L90 six speed automatic should get city mileage in the low teens and is capable of highway values in the low twenties. Not Prius territory, but very impressive for such a vehicle. The new diesel will go on sale in early second quarter of 2010.