What kind of engine is Audi A8?

Audi A8 has four displacement options, which are equipped with 2.5L V6 FSI direct injection engine, 3.0L V6 TFSI turbocharged direct injection engine, V-8 cylinder 4.0L V8 TFSI turbocharged direct injection engine and 6.3L W 12 FSI engine.

1 and FSI engines

FSI engine is stratified fuel injection, which is a technology based on in-cylinder direct injection engine. Compared with the traditional port injection ignition engine, FSI directly injects fuel into the combustion chamber, which optimizes the charging efficiency due to the gasification cooling effect of the spray.

Due to the quality adjustment of gasoline engine, there is no need for throttle valve, which greatly reduces the intake loss, and stratified combustion reduces the heat transfer loss of the engine, thus improving the output power at full load and reducing the fuel consumption at part load.

2.TFSI engine

TFSI engine is the abbreviation of turbocharged stratified fuel injection engine, which can be said to be the combination of FSI engine and turbocharger, that is, turbocharger +FSI.

FSI features

It can reduce the pumping loss and ensure low load and low fuel consumption, but it needs to add a special catalytic converter to effectively purify and treat the tail gas. Elaborate as follows:

FSI engine can basically automatically select two working modes according to the engine load. It is stratified lean combustion at low load and homogeneous theoretical air-fuel ratio (14.6- 14.7) combustion at high load. In these two operation modes, the injection time of fuel is different, and the on-off valve actuated by vacuum is opened/closed.

In homogeneous theoretical air-fuel ratio combustion under high load, fuel is injected in the intake stroke. Homogeneous mixture with theoretical air-fuel ratio is easy to burn and does not need to rely on vortex action. Therefore, the on-off valve is opened because the air intake resistance is reduced.

In addition to full load, exhaust gas recirculation is carried out to limit pumping loss. Due to direct injection, the compression ratio is increased to 12. 1, and even under homogeneous theoretical air-fuel ratio mixture combustion, fuel consumption can still be reduced.

Furthermore, in the FSI engine, between low load and high load, homogeneous lean combustion is set to the third operation mode, in which fuel is injected in the intake stroke, and the on-off valve is closed due to the longitudinal vortex that accelerates the combustion of lean mixture. At this time, the exhaust gas recirculation (EGR) that hinders combustion will be temporarily suspended. Different from homogeneous theoretical air-fuel ratio combustion, the intake air exceeds the fuel injection.

Baidu Encyclopedia -TFSI Engine

Baidu Encyclopedia -FSI Engine