What is per-ignition????
What is per-ignition????
Pre-ignition:
Is the
ignition of the homogeneous mixture in the cylinder, before the timed ignition
spark occurs, caused by the local overheating of the combustible mixture? For
premature ignition of any local hot-spot to occur in advance of the timed spark
on the combustion stroke it must attain a minimum temperature of something like
700-800 degree centigrade.
·
Pre-ignition is
initiated by some overheated projecting part such as the sparking plug
electrodes, exhaust valve head , metal corners in the combustion chamber,
carbon deposits or protruding cylinder head gasket rim
·
However, pre-ignition
is also caused by persistent detonating pressure shock waves scoring away the
stagnant gases which normally protect the combustion chamber walls. The resulting
increased heat flow through the walls raises the surfaces temperature of any
protruding poorly cooled part of the chamber, and this there-fore provides a
focal point for pre-ignition.
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