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>From: Toby Erkson <Toby_Erkson@ccm2.hf.intel.com>
>I found your description of the knocking *very* helpful. I have had this
>problem in the past and just shrugged it off as a "cooling tin vibrational
>frequency" that my engine was producing at the low RPM, high throttle
>position. Luckily I had the good sense to stop what I was doing that was
>causing the "vibration". Now I know what knocking (in an engine) sounds
>like.
>
>I am assuming that pinging is similar but, of course, at a higher tonal
>frequency -- is that correct? Could you describe what pinging sounds like?
> I'm guessing that it would most likely occur at higher RPM and on an
>engine that is running hotter than stock. What ya say?
It is my understanding that knock and ping are exactly the same thing, just
to different degrees. By this I mean that they both happen under the same
conditions, but knock is louder, and, I assume, more destructive. Just
another example of our language getting mucked up by the marketing types for
the sake of sales.
You know: "So you think YOUR brand of gasoline helps prevent knock? Well MY
brand prevents knock AND ping!" Funny thing, they were both just adding
tetraethyl lead.
The word preignition is sometimes used to describe two things, one of these
is knock and the other is ignition of the mixture before the spark by
something hot in the combustion chamber. Octane will cure knock, but only
fixing the premature ignition source will cure the latter.
Knock is spontaneous ignition of some part of the mixture after the spark
has occured but before the flame front has reached that part of the
combustion chamber.
Jim
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Melissa Kepner Jim Adney
jadney@vwtype3.org jadney@vwtype3.org
Laura Kepner-Adney
Madison, Wisconsin
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