TDI Engines.

For many years now, Volkswagen has been one of the leading makers of advanced diesel engines. Volkswagen’s innovative unit injector engines, for instance, met the limits of the EURO 4 emissions standard long before its introduction. This demonstrated the leading position of Volkswagen engine technology in the development of efficient and eco-friendly diesel engines. Today, Volkswagen offers a broad range of three to ten-cylinder turbodiesels with reliable and economical diesel engineering based on unit injector systems or common rail injection.

The pressure at which the diesel is injected into the cylinder is the key factor in diesel direct injection. The diesel fuel has only an extremely short time in which to mix with the highly compressed air in the cylinder. The higher the injection pressure, the more finely the diesel is atomised in the engine combustion chamber. This ensures an intensive mixing of the fuel and air particles. A higher mixing intensity leads to better and more efficient combustion. The energy stored in the fuel is then used more effectively and, in addition, pollutant emissions are reduced.

To further optimise the combustion processes, Volkswagen implements various injection stages within one power stroke – referred to as multiple injection. Depending on the engine design, revs and load, modern diesel engines use a pilot or double pilot injection, a main injection and a post injection. Pilot injection has proved the ideal solution for achieving smooth combustion by ensuring that the extremely high pressures that occur in the combustion chamber are reached not instantly, but more gradually. This considerably reduces combustion noises and cuts nitrogen oxide emissions. The objective of post injection is to further optimise the combustion process and thus achieve even lower exhaust emissions.