GM Comes Clean With New Duramax Diesel Engine

Todays diesel engines are nothing like they used to be. Efficient, quiet, smoke free, and quick, these engines are the core of many products sold across the globe. In North America weve seen a couple of these motors sneak by in Mercedes-Benz and Volkswagen products, but for the most part diesels are left to the heavy-duty truck market. Most diesels here have been relegated to a life of brute force for towing, hauling and generally muscling about in commercial grade vehicles, and as a result, have not been subjected to the same stringent emissions rules as passenger cars. Starting in 2007, though, all diesels will be forced to comply with strict new laws.

Granted that the market for diesel trucks is simply huge, GM couldnt just idly sit by, it upped the ante by refining the Duramax diesel lineup. The result of its efforts is this, the 6.6-liter Duramax V8 turbo-diesel, an engine that will be offered on the Chevrolet Silveardo 2500 HD / 3500 HD, GMC Sierra 2500 HD / 3500 HD, as well as the Chevrolet Kodiak and GMC TopKick. On the surface, these engines dont appear to be different; they look the same, and they offer the same horsepower - up to 350 hp and a mountain-moving 650 lb-ft of torque; but the fact of the matter is that this new engine is capable of producing some 90-percent fewer particulates (the black, sooty fumes), and 50-percent fewer NOx emissions.

Cleaning up a workhorse diesel engine isnt exactly the easiest of duties, but GM did the job by applying the latest in modern diesel technology. The big addition to the Duramax engine is the DPF Diesel Particulate Filter. This device consists of a special catalyst which allows the soot and harmful, dirty matter to be captured in a ceramic honeycomb brick. The filter is also self-cleaning; once it is sufficiently dirty, its regenerated to its clean state by burning off the soot using extra high temperatures. Although this kind of filter is new on GMs diesel motors, its been in place for a few years now on passenger cars in Europe. The net benefit is a serious cutback in emissions, allowing for some of the cleanest vehicles on the road.

Of course, the filter isnt the only new addition to the engine; GM took the opportunity to upgrade the rest of the engines components too. The 6.6L Duramax now features a new 32-bit processor to control fuel flow for different loads, has a new variable geometry turbocharger, heavier-duty fuel injectors capable of pumping diesel at more than 26,000 psi (up from 23,000 psi), and has new glow plugs for faster starting times. With these changes come a strengthened block and upgraded main bearings. All of these improvements will, however, require the use of new low-sulphur diesel, which is slated to hit fuel stations this fall. The new diesel is key to the particulate filters success, as it only contains 15 parts per million of sulphur, down from the current 550 parts per million. If our current diesel fuel were used, the engine wouldnt last long.