[ST] General thoughts on ping

[Jonathan West <triumphnutter@xxxxxxxxx>]

So, I don't know who originally posted the original "ping" thread but here's my
thoughts on it.  Sorry it's late, I'm just getting caught up from the holiday
weekend.

Ping=pinking=kock and ping=detonation.  It's all the same thing.  It can be
catastrophic to an engine if ignored.  It can warp pistons, damage valves,
destroy rings... any number of really bad things.  It literally hammers the
combustion chamber when it happens.  It is nothing more than part of the
fuel/air mixture exploding prematurely due to a number of different causes. 
Essentially, the fuel air mixture is ignited by the spark, and the resultant
flame travel and gas expansion compresses the rest of the mixture to the point
that it detonates prematurely before the flame travel can consume it.  It's
like two different explosions, and the combination of the two is way more than
the parts were ever meant to handle.  The poor timing of the second explosion
is counterproductive to the mechanical efficiency of the power stroke.  It can
be catastrophic.   

How do you eliminate it?  There are a number of factors that affect it.  
1) Detonation thrives in high temperatures.  Try to avoid heavy throttle in
slow moving traffic where the engine temps might be higher.  Also, full
throttle at low rpm increases the combustion chamber pressures moreso than full
throttle at high rpm, so know that you are inviting detonation by doing this in
an engine that is susceptible to it.  
2) High Octane fuel helps quell it due to the slower burn rate.  The slower
burn rate helps mimimize the compression of the unburnt fuel so it does not
ignite prematurely.  That's why the best octane fuel is the lowest octane you
can run without detonation.  
3) Retard the ignition timing.  Starts the whole ignition process later in the
stroke giving it less chance of detonating due to lower compression speed. 
Obviously you're not gonna change this without a tuneboy.
4)Reduce compression ratio.  Clean out any carbon buildup on the piston or
chamber that is consequently shrinking your combusion chamber volume, and
thusly raising your compression ratio. 
5)Sometimes a colder range spark plug can help... all this does is dissipate
more heat into the head, so depending on the design of the combustion chamber
and how the flame propagation and travel was originally designed and
anticipated, this may or may not help.  In other words, you could be putting
more heat into the wrong place with a colder plug. 

Incidentally, my 99 ST started doing this same thing on 89 ocatane fuel.  I've
been using 91 or better and have not had any issues.  I have to wonder if there
is substantial carbon build up now with 24k miles.  It did not always do it.  I
would also be inclined to believe that the fuel quality is not what it was
years ago.  

Anyway, hope this helps whoever was having trouble.  

Good luck,
Jonathan West


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