A turbocharger comprises a turbine driven by the exhaust gas flow and a compressor for the intake air. The two components are mounted on a single shaft. The performance specifications of modern-day Audi turbochargers are impressive. The turbocharger of the new 3.0 TDI engine builds up to 2.0 bar relative charge pressure, and at full load can theoretically compress 1,200 cubic meters (1.44 metric tons) of air an hour. Its driving power is around 35 kW and it achieves a speed in excess of 200,000 rpm.
Audi’s ongoing advancement of turbocharger technology is focused particularly on efficiency, torque development, transitional behavior, acoustics, and lightweight construction. Progress is being made through innumerable single steps, and in many cases by increments of thousandths of a millimeter. Exhaust gas temperatures, reaching peaks of 830 degrees Celsius (1526 degrees Fahrenheit), impose high demands on moving parts, and any further rise necessitates the use of new materials.