Tech: Getting the Ignition Timing Right
People always talk about air/fuel ratios, but setting the correct ignition timing on programmable management is at least as important to getting good performance, economy and responsiveness.
When to Fire
The period between the spark firing and the complete combustion of the fuel/air mix is very short – on average only about 2 milliseconds. Ignition of the fuel/air mix must take place sufficiently early for the peak pressure caused by the combustion to occur just as the piston has passed Top Dead Centre, and so is on its way down the cylinder bore. If the ignition occurs a little too early, the piston will be slowed in its upward movement, and if it occurs too late then the piston will already be moving downwards, so reducing the work done on it. If the spark occurs much too early, the ignition pressure wave can ignite the mixture in various parts of the combustion chamber, causing detonation. (mais…)
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