Naturally aspirated high revving high performance engines are characterised by some characteristic design features. In order to achieve the desired performance optimised ports, a compact combustion chamber with central spark plug position and maximised valve size are necessary preconditions.
When applying an injector for direct injection it has to be considered that above mentioned design features are not influenced negatively. Depending on the layout of the cylinder head the injector position has to be optimised under consideration of the above mentioned boundary conditions. The analysis of various injector positions leads to the result that the optimal injector position for a 4 - valve engine is between the intake valves and below the intake port. A steep intake port as it is common for high performance engines is very advantageous for this layout. Furthermore it has to be considered that the shape of the combustion chamber is not disturbed by the application of the injector.
The fine tuning of the injector position and the inclination of the injector has to ensure that no impingement of the spray on cylinder wall and piston occurs. Special attention has to be paid on the moving parts like piston and valves.
The consideration of these guidelines during the design is imperative to avoid oil dilution, soot formation and carbon deposits and to ensure a trouble free engine operation.
During the design many accompanying work steps like simulation, hardware test and flow tests ensure an optimised engine design.
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