Clean, 'Green', Fuel Efficient Diesels At Home on Race Track or the Highway

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Modern diesels are cleaner than ever before, and to show how efficient they are, the latest generation made its debut on the racetrack, proving that even under rigorous full race driving conditions the diesel vehicles remain clean and green -- and highly fuel efficient! Thirty of the new VW Jetta Diesel TDIs, powered by a 2.0-liter four-cylinder that produces 170 hp and 258 lb.-ft. of torque, tackled some of the top road racing courses in North America in the Volkswagen Jetta Diesel TDI Cup, a multi-race series of basically stock Jetta 'clean diesels' racing hard at major road tracks from Lime Rock to Road Atlanta.

"What we have here are virtually stock diesel passenger cars that raced hard throughout the summer and fall, averaging fuel mileage in the mid-twenties and running absolutely clean under very tough full road race conditions. This is green personified," says Wolfgang Hustedt, Motorsports Manager for Bosch, which supplies the advanced fuel system that helps make these vehicles fuel efficient and 'green.'

'Common Rail' Key to Efficiency

The heart of these clean, highly efficient engines is a Bosch common-rail fuel injection system that uses fast, precise Bosch piezoelectric fuel injectors, instead of a traditional mechanical system. This technology permits higher injection pressures, which better atomize the fuel, enhances performance and makes it easier to control pollution.

"This is the stock setup for the VW Jetta Diesel TDI, basically the same engine and car any motorist would get if he picks one up and takes it home with the addition of racing ABS brakes and suspension," Hustedt says. "This advanced diesel technology allows the vehicle to become the first automobile to meet the world's most stringent emission control standards, California's Tier II, Bin 5."

Keys to the high fuel efficiency and low emissions are the advanced Bosch common rail fuel delivery system and piezo fuel injectors. Resembling fuel injection systems for gasoline engines with electronic sensors and a computer -- but with much higher fuel pressures -- diesel fuel is pressurized along a "common rail" for delivery to electronically activated injectors for each cylinder.

Fast Acting Injectors Play a Big Role

The latest common rail system relies on highly precise rapid-switching piezo injectors, which have 75 percent fewer moving components and mass, allowing them to switch at double the speed of previous solenoid-valve injectors. This allows the piezo injectors to significantly lower diesel emissions, increase the achievable engine power and noticeably lower engine noise - depending on the specifics of the engine.

"The Jetta TDI diesels operating with this system are very powerful with lots of torque in addition to high fuel efficiency and very low emissions -- and let me say again, they are very, very quiet," Hustedt observes.

"In older diesel engines, pressure in the fuel lines opened spring-loaded injector valves at about 4,000 pounds per square inch, and the fuel management system was almost entirely mechanical," Hustedt says. "Higher pressures in the new electronically controlled systems -- over 24,000 PSI -- allow injectors to deliver finer atomization of the fuel, while improving combustion efficiency and lowering particulate emissions."

To help make it 'green,' in addition to the sophisticated Bosch fuel system components, the Jetta also uses a NOx-storage catalyst, which is basically a reservoir that temporarily holds the noxious emissions, like a particulate filter, until they can be burned off during one of the engine cycles.

To learn more about the technology behind clean, green diesels, visit www.boschautoparts.com.