Ideas on stoppin some pingin? (long)

[Bruce.Hearn@cd-tech.com]

Tim asked:
>A question for Bruce and others in the know:
>I know that a lean mixture caused high combustion
>temperatures, but does it directly cause preignition
>as well?

Preignition is combustion caused by a hot spot acting as an ignition source
in the cylinder before the spark plug fires.  Knock or detonation is
uncontrolled combustion after the spark plug has started normal combustion.
A lean mixture could cause something in the cylinder to get hot enough to
cause preignition, quite often the spark plug ground electrode.

End gas is also present in the boundary layer.  As Tim stated, detonation
will scour this boundary layer away and expose the cylinder and piston to
higher temperatures than normal.  This and the concussive shock eat away at
pistons and valves resulting in burned valves and holed pistons.

Another unsolicited tid-bit: Most heat transfer through the head is via the
exhaust ports.  Once again, Kevin Cameron at Cycle World elucidates engine
minutae. This guy knows his sh!t.

Bruce back in Houston