In 1989, Audi introduced a new engine at the IAA Frankfurt Motor Show. This new engine was the first of its kind, and the first in a long line of ‘TDI’ engines, a 2.5 liter five cylinder direct injection turbocharged diesel engine with fully electronic engine management. First installed in the Audi 100 it generated 120 horsepower and 195 lb-ft of torque, thanks in part to a distributor type fuel injection pump that could build up a maximum pressure of 13,053 PSI (900 bar), which helped promote more efficient combustion of the diesel fuel. After further work on the injection pump and exhaust gas recirculation, output eventually climbed to 140 horsepower in the A6.
4 Cylinder Engines
In 1991 the first 1.9 liter (and the first four cylinder) TDI engine was launched in the Audi 80, and later the Audi 100. Fuel injection pressure was up to 13,779 PSI (950 bar), and this engine developed 90 horsepower and 134 lb-ft of torque. In 1995 the engine was updated with a variable turbine geometry (VTG) turbocharger, and power climbed to 110 horsepower and 166 lb-ft of torque. This revised engine was used in the A3, A4, and A6. In 1999 the 1.9 TDI got pump-nozzle fuel injection technology and water-cooled exhaust gas recirculation. Fuel injection pressure was up to 29,733 PSI (2,050 bar), and power was up to 115 horsepower and 210 lb-ft of torque. Later, 100 horsepower and 130 horsepower versions would also be available.