[s-cars] S6 pinging woes - the continuation

Brett Dikeman brett.dikeman at gmail.com
Mon Jul 27 20:43:38 PDT 2009


On Mon, Jul 27, 2009 at 10:05 PM, Cody Forbes<cody at 5000tq.com> wrote:

> Even if the problem is pre-detonation pinging by now it is very likely
> that a piston ring or a piston is damaged. In my experiance with these
> engines (I've killed a few of them running over 30psi) it seems the
> pistons are so good that they'll take the detonation for a long time

There are some inaccurate terms being thrown around...

Pre-ignition is when the fuel-air mixture ignites in a controlled burn
but does so prematurely.  Typically a hot spot touches it off, but
there is a relatively smooth progression of the burn.  The burn may
happen more slowly, as compression is lower (flame front speed
increases with compression.)

Detonation is when the fuel doesn't progress in a smooth flame-front
from the plug- ranging from multiple ignition points to spontaneous
combustion of the entire mixture.  I'm not sure if it qualifies for
the chemist's definition of an explosion, but the temperatures and
pressures far exceed normal values.

Brett


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