Audi FSI: More power, but less fuel

In an automotive showcase "The Winnipeg Free Press" is reporting that the Audi direct injection FSI engines provide more power, but need less fuel. And in addition, Audi's FSI resolves emissions problem, allows for smaller engines, and leaner mix.

LAST week, I started presenting the candidates for Best New Technology as presented last month at Canadian Car and Truck of the Year near Belleville, Ont. Audi's FSI fuel system is one of these new technologies.

FSI (fuel straight injection) or more commonly known as direct fuel injection, has entered the Canadian market. Companies such as Mitsubishi and Nissan have been using direct fuel injection overseas for years, but there have always been difficulties in meeting North American emissions standards. The latest designs have overcome these difficulties and now Audi is making it available on their A6, A4 and A3 models.

Direct fuel injection is distinctly different from the port fuel injection systems we currently find on almost all gasoline-powered vehicles. Port injection sprays the fuel into the engine's intake manifold near the back side of the intake valve a few degrees of crankshaft rotation before the intake valve opens. As the valve opens during the intake stroke, the air/fuel mixture is drawn into the cylinder as a homogenous mixture. This mixture is then compressed when the piston rises on the compression stroke and ignited by the spark plug.

Direct injection is currently used on many diesel engines, and the gasoline direct injection uses similar principles. The injector sprays fuel directly into the cylinder. Only air enters past the intake valve. On diesel engines, the fuel starts burning as soon as it is injected due to the high heat of compressed air in the cylinder. On direct injection gasoline engines, the fuel is still ignited by the spark plug, because compression ratios in gas engines don't compress the air high enough to generate as much heat.

Introduced first in the 3.2 litre V6 in Audi's A6 sedan, this gasoline direct injection offers both increased power and fuel economy. A high (for gas engines) compression ratio of 13.2:1 is used and the fuel is injected late in the compression stroke so that it doesn't have time to pre-ignite.

GermanCarBlog, Audi VW Volkswagen

Source: The Winnipeg Free Press via AudiWorld, logo by Cartype

Watch more TV. The German Car TV.

Read more