The initials Fuel Stratified injection (direct gasoline injection) gave the FSI system its name. Its fundamental logic is direct gasoline injection.
FSI engines inject the fuel directly into the combustion chamber and not into the manifold like standard engines. In systems with manifold spraying the injection pressure is set at 4 bar, but it reaches 10 bars in FSI. Tumbles are moving plates that impart a spiral motion to air as it travels through intake manifolds towards the cylinders. The piston head has a special shape that looks like a wave and allows the ready-to fire air-fuel mixture to be collected within the vicinity of the spark plug.
All this has one goal: low fuel consumption. FSI technology allows fuel to be sprayed directly into the combustion chamber as a fine spray. This prevents fuel from being thrown away and increases engine efficiency.
TFSI, however, was named after the initials of Turbo Fuel Stratified injection (Turbo powered direct gasoline injection engine). TFSI engines use a common fuel supply system, which is controlled by a high-pressure pump.
The fuel is directly injected into the combustion chamber using an injector that is located between the intake valves. It can be controlled with millisecond precision, and up to 110 bar pressure. The mixture of fuel and air is evenly distributed within the combustion chamber. This is what distinguishes the TFSI from other engines. It provides high performance at all engine speeds.
Modified intake manifold shapes are used on cylinder heads with low friction valve pushers. They allow for more airflow that naturally aspirated FSI engines. This improves efficiency and knock resistance as well as smoother operation. This allows the turbo engine to reach a compression ratio (10.5:1). It plays an important part in increasing the thermodynamic efficiency of turbo engines, both conventional and atmospherically-fed.
The engine block is made from GG 25 gray cast Iron. This material is extremely sound-resistant and high in pressure. An enhanced sound quality can be achieved by using a mass-balanced transmission device.
The engine’s calmness is also compensated for by the two balancer shafts. They rotate twice as fast at the crankshaft. The crankshaft transmits engine power through a triangular link. This chain drives the oil pump as well as the balancer shafts. This combination allows for very high vibration characteristics in a turbocharged four-cylinder engine.
