Will diesels shake off a bad image? (WIP).

S.M. Shahed, vice president, Advanced Technology, at Garrett Engine Boosting Systems doesn't mince words when talking about the comparatively dismal performance of diesel engines of 20 years ago: "Diesel was a dog. And that's why we have this lingering picture of this noisy, dirty, smelly dog." But, Shahed says that diesel's days in the doghouse are over, at least for most of the planet outside of the U.S. The challenge now faced by Garrett, which produces millions of turbochargers for diesel engines, and the rest of the diesel industry, is to change diesel's mutt-like image in the minds of the American public.

The contemporary common rail turbocharged diesel is markedly different from its 1980s-era predecessors that spewed clouds of black smoke. Particulate and NOx emissions from diesel engines have dropped precipitously in the last ten years, and are projected to be a tiny fraction of even current figures by 2007. (Particulate emissions of 0.6 g/bhp/hr measured in 1988 dropped to 0.1 in 1998 and are forecast to be at 0.01 by 2007. Similarly. NOx emissions of 10.7 g/bhp/hr in 1988 fell to 4.0 by 1998 and should reach 0.2 by 2007.) Performance has improved dramatically with torque ratings that rival or better gasoline-powered engines and the near elimination 01 the infamous turbo lag. And fuel economy is unbeatable. Garrett compiled a list of ten production cars that are offered in both gasoline- and diesel-powered versions and the diesel models got about 50% better mileage across the board.

So it is not surprising that in countries where fuel is much more expensive than it is in the U.S. (i.e., most of the rest of the world) diesel is steadily making inroads. Austria and France already have diesel penetration rates of around 50%; Garrett projects diesel penetration in Europe to increase from 30% to 50%. Worldwide, the company forecasts 12% growth every year for the next five years.

Garrett posits that the turbocharger's ability to squeeze out more torque and power from an existing engine is a big factor in diesel's projected growth. Their reasoning: as emissions standards tighten around the world and fuel economy becomes more important, automakers will have to turn to smaller displacement engines. Since turbochargers can make smaller engines crank out power and torque similar to their bigger, thirstier counterparts, turbocharged diesel engines will become a natural powerplant choice, Q.E.D.

The discrepancy in this otherwise rosy global scenario is the U.S. of A. where, in addition to the "dirty dog" perception of diesels, the efficiency of turbocharging is largely discounted. In America, engine potency is measured by the number of cylinders, so the beauty of a four-cylinder engine that has the same power and torque as a six (and is more fuel efficient) is largely lost. The disappointment with this state of affairs by the people at Garrett is almost palpable. Shahed points to a picture of an urban bus belching noxious fumes and says that in America, "People have an experience like this stuck in their minds. They need to experience the modem diesel."