True definition of Knock

[Len Sabatine]

   How About the " Low Octane " portion of the mix in the chamber igniting 
before
  the piston reaches past dead stroke position , causing the piston skirt 
to be "jammed"
  into the cylinder wall. The "rattle" is then transferred in to the 
Cylinder case, the sensitivity
  would vary as to the physical construction of the cylinder case [block 
casting] , water
  jacketing , cylinder wall core thickness , firing order and the 
particular engine design's
  tendency to detonate. Add to this " which is the Hungry Hole " , the 
cylinder most likely
to initiate detonation ignition response. Wonder Why there's so many 
different KS locations
and sensitivity variants. The factory also factors in long term piston / 
wall clearance etc,
into the  frequency response / programming.  Add a bit of oil into the 
chamber and run the
lead to far BTDC should really get the pot boiling.  Then throw in all the 
component damage.
While Mr. Smith's explanation is excellent , I believe it's a bit more 
complex in total scope
though. Anyone is free to disagree .
Len

>Totally, self explainatory
>Grumpy
>
> > "Knocking occurs when a minute portion of the most volatile component of
> > gasoline reaches the cylinder a fraction of a second before the principal
> > fuel charge, which is supposed to arrive at the instant the spark plug
> > fires.  When the more volatile fuel arrives early, the heat and
>compression
> > inside the cylinder cause it to ignite before the main charge, which in
>turn
> > causes the knocking you hear."
> >           --Bruce W. Smith, Auto World Weekly (July 18, 2000)
>
>
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