Petrol direct fuel injections have in general the advantage that all fuel evaporates in the cylinder space. Therefore, the internal cooling is stronger, it can be operated, in principle, with a higher compression. It is proven by one of the first direct fuel injections with turbo-supercharging. The compression of 10,5 : 1 is relatively high, for a charged engine.
How it works
The combination is already known from racing. It is first implemented into a car: the Audi A3 with a four cylinder in-line engine. The car features two offset shafts and an infinitely adjustable intake camshaft. The injection pressure is 110 bar. Looking at the company philosophy as well as the fact that it remains a sporty vehicle, a stratified charge operation is not considered for saving fuel. The engine is operated homogeneously with conventional exhaust gas system.
This vehicle allows a comparison to the charged diesel direct fuel injections. There are certain approaches in terms of torque (slight advantages for the diesel engine) and in terms of the nominal rotation speed (clear advantages for the petrol car). Even the mileage is well enough, in spite of the abandonment of further reaching fuel measures, however, the mileage will be much worse once the engine performance is used.