At the 1989 German International Motor Show in Frankfurt am Main, Audi presented the world's first diesel engine for passenger-car use, with direct fuel injection and all-electronic engine management, and gave this revolutionary technology the name TDI.
First used in the Audi 100 Avant early in 1990, this remarkable new development on the passenger-car diesel market gave the diesel a totally new image almost overnight: instead of slow-moving, loud and unrefined, it was now agile, smooth and quite exceptionally economical. The Audi TDI achieved a dual emotive effect by uniting dynamic, sporting character with low consumption and a correspondingly useful operating range before having to refuel. One could say that nothing remained of the traditional diesel except its proverbial long life.
Ten years of tradition and success thus provide a welcome opportunity to look back, but also to examine future prospects and developments. Audi will continue to pioneer TDI progress in accordance with its famous "Vorsprung durch Technik" slogan and to play a leading part in the competition to supply the products that the market and the customers demand.
Authority derived from experience
Audi benefits from the TDI know-how it has built up during ten years of market presence, and is able to utilise the individual advantages of all the direct-injection systems currently offered for sale in a manner which ideally suits the intended purposes and offers the customer maximum benefit. These systems are:
First, the well-proven and successful rotary-pattern injection pump. It produces a well-shaped injection pattern and has a high pressure potential, extending up at the moment as far as 1850 bar. It is easy to install on the engine, can be used on engines with up to six cylinders and has a pilot injection facility.
Second, the pump-injector system, which features compact modules for each cylinder of the engine. It is particularly suitable for 3- and 4-cylinder engines with two valves per cylinder, but can in fact be installed on engines with any number of cylinders. Additional advantages are the pilot injection facility and the very high pressure potential of more than 2000 bar.
Finally, the common rail system, in which pressure is built up permanently; it permits considerable freedom in determining the pattern of pilot, main and post-injection, and the pressures concerned can be chosen freely even at low engine speeds. This system is straightforward to install on the engine and has particularly compact injectors. Although the maximum pressure is currently in the region of 1350 bar, the system clearly has plenty of future development potential.
10 Years of Audi TDI Technology (Intro)
Outlook: Audi A8 3.3 TDI quattro
Outlook: Audi A6/A6 Avant 2.5 TDI
Outlook: Audi A4 1.9 TDI
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