irishcar.com

23 July 2002: The FSI petrol engine technology which enabled the Le Mans conquering Audi Infineon R8 sports cars to race harder and longer between fuel stops is to be made available in the marque's A4 road car.

The new combustion system brings lower exhaust emissions, improved fuel economy and increased power and torque compared with an equivalent, conventionally injected engine.

The new Audi A4 2.0 FSI will be positioned between the continuing 130bhp 2.0 model, over which it carries a price premium, and a revised 163bhp 1.8 T.

With 150bhp and 200Nm of torque, the FSI saloon can reach 62mph from rest in 9.6 seconds and continue to a 135mph maximum speed, yet at the same time is capable of achieving just under 40mpg in the combined cycle.

Fuel is delivered straight to the cylinders by a high-pressure common rail injection system supplied by a single-piston injection pump – rather than into the intake manifold, as is the case with most petrol engines.

The engine is able to to operate in two ‘modes’. When a high power output is required, the electronics select the homogeneous mode, which is the normal operating state for conventional indirect injection engines. Even in this mode, the FSI engine holds an advantage over less advanced petrol units in that it leaves no fuel unburned – the mixture is completely vaporised in the combustion chamber for greater efficiency.

At normal cruising speeds, under part load, the engine switches to ‘stratified charge’ operation. In this state, the air, or ‘charge’, is directed extremely accurately towards the spark plug using a ‘tumble’ principle, created by a tumble flap within the intake manifold and a specially shaped bowl in the piston crown.

Fuel is injected only in the piston’s compression phase, rather than during induction as is the norm, and is placed in the tightly controlled stream of intake air moving towards the spark plug. The combustible mixture is therefore only present in a restricted area of the combustion chamber, surrounding the spark plug, and injection takes place at a very shallow angle, minimising the potential for losses.

For the best possible engine efficiency, and therefore lowest fuel consumption, ultra- low sulphur or sulphur-free fuel is recommended for use in FSI-powered models. However, the new engines are also designed to run on 98RON super unleaded or 95RON unleaded with virtually no losses in performance or economy.

The power outputs of the 1.8 T petrol and 2.5 TDI engines in the A4 saloon and Avant range have been increased to 163bhp in both cases, up from 150bhp in the original 1.8 T and 155bhp in the outgoing 2.5 TDI.

No prices or availability have yet been announced for Ireland.