Audi has been building highly efficient combustion engines for many years. That applies not only to the TDI, which Audi pioneered, putting the first engine onto the market in 1989, but also and in particular to the spark-ignition engines. The abbreviation FSI stands for petrol direct injection. Together with the additional letter T it means there is also a turbocharger. Audi’s TFSI engines play a pioneering role in the field of compact, lightweight and highly efficient 4-cylinder engines, and the current V6 FSI enjoys top ratings among its competitors thanks to a whole package of technological innovations. A turbocharged 4-cylinder direct injection petrol engine achieves fuel savings of 10 – 15 percent compared to a conventional V6 naturally aspirated engine.
FSI technology, where the fuel is injected directly into the combustion chambers, is thermodynamically superior to conventional intake manifold injection systems. Preparing the mixture in the combustion chamber removes heat from the fresh air drawn in. The result is a higher mixture density that increases the charge and at the same time reduces the tendency to knock. This allows ignition timing that is superior from the point of view of efficiency. The upshot is greater compression, which in turn improves effectiveness and thus efficiency. This enables the FSI engines to develop more power and dynamism with lower fuel consumption.
Combined with a turbocharger, FSI technology displays even greater potential. This was demonstrated for the first time in June 2001, when a TFSI engine powered the Audi R8 sports prototype to overall victory in the Le Mans 24 hour race. In the years that followed it won a further 64 races in 80 starts all around the world. In particular it was the extra range resulting from the lower fuel consumption that gave the direct injection engines the edge over the competition.
Source: Fourtitude, picture by AudiWorld