Knock...

[Mike Palmer]

>>Just interested in other's ideas how this might actually work.  How could 
>>plug gap resistance after the spark tell you anything about detonation?  Can 
>>the plug gap "taste" the residue of preignition as being different from the 
>>"taste" (er..resistance) of a slowly propagting flame front that results 
>>from correct ignition?
>
>Kenne-Bell is marketing an ignition controller for Syclones/Typhoons that
>can supposedly detect detonation in each cylinder and retards timing only
>in that cylinder. Since they don't use a knock sensor for each cyl., this
>must be how they determine whether or not a cylinder is detonating.
>
>Could it be that they are considering unusually high cylinder pressure to
>be equal to detonation? The resistance of the gap would go up, the current
>would drop- there's your detection. Sounds a lot like a Jacobs ignition.
>
>Dig
>sdbartho at hwking.cca.rockwell.com

Hmmm. Since detonation occurs generally a goodly amount of time after the
primary spark has ignited the mixture, in order to determine a gap
resistance value they'd have to keep peppering the plug with sparks
and monitoring firing voltage. If this is the case, then how do they get 
sufficient coil saturation between "check-sparks" to induce enough
secondary to actually fire the plug? If they don't measure gap resistance
this way, then how exactly do they do it (i.e. measuring the effective
gap resistance over the course of the combustion period to detect unusual 
pressure gradients indicating abnormal combustion)?

Just curious...




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- MJP