At Audi, TFSI stands for the combination of two of the brand’s core areas of expertise – direct injection and supercharging. Audi was the first manufacturer worldwide to combine turbocharging and direct injection in volume production. Usually a turbocharger is used. In the case of the new V6 3.0 TFSI, a compressor offers advantages in terms of the overall concept and power characteristic.
As petrol direct injection draws heat from the combustion chambers, it solves a fundamental problem posed by all supercharged engines: high-pressure charging of the combustion chamber and the resulting increased tendency to knock (uncontrolled self-ignition of the mixture at hot points of the combustion chamber) if engine compression is not reduced at the same time. With its TFSI engines Audi can achieve efficiency-enhancing compression ratios of more than 10.0:1 – previously only attainable by naturally aspirated engines. This significantly improves engine efficiency and performance – and consequently power build-up. Injection pressure on the current TFSI engines is up to 150 bar.
TFSI is one of the key technologies in Audi’s downsizing strategy, which aims to substitute engine displacement with supercharging without forfeiting dynamism. It already operates in the majority of the highly popular four-cylinder petrol engines – the 1.4 TFSI, the 1.8 TFSI and the 2.0 TFSI. The new 2.5-litre five-cylinder TFSI in the Audi TT RS is another particularly emotionally charged example of high performance combined with outstanding efficiency.
(pictured to the right of the engine) is driven by the exhaust-gas flow and compresses the intake air. Since the air is heated during the process, an intercooler is mounted downstream of the turbocharger to reduce the temperature. Its density thus increases and the air/fuel mixture in the combustion chamber remains cooler.
