A precondition for a fast lap time of a motorcycle is an engine which can be controlled by the rider easily. The behaviour of the engine is influenced by the engine concept, firing order and various devices which give the possibility to realise a traction control. One example is an electronic throttle actuation (drive by wire) which offers the possibility to overrule the rider’ s input via the throttle grip.
Further solutions to realise a traction control are enleanment of the mixture, spark retardation and retardation of start of injection (SOI) of a direct injected engine.
When varying these parameters it has to be considered that the exhaust gas temperature does not exceed a certain limit. As shown in picture 'Fast traction control by varying of different parameters' SOI retardation of a DGI engine provides the widest adjustment range before the limitation given by the exhaust gas temperature is reached. Therefore DGI offers the most effective fast traction control.
Beside the target to achieve the fastest lap time a traction control is also a safety feature for less experienced riders. Under consideration of the steadily increasing performance of motorcycles offered on the market this feature may become indispensable in the near future.
Generally DGI leads to an improved driveability since the transient engine operation can be controlled easier. The reason is very simple. DGI provides the fuel where it is needed - in the combustion chamber. Therefore the element of uncertainty caused by the wall film (picture 'Area covered by wall film; 4 - stroke engine with PFI') in the intake ports is eliminated.
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