Electronic Detonation Sensing
Engine detonation can be electronically sensed by any of the following means:
pressure sensor installed flush with the combustion chamber
pressure sensor connected to the spark plug
temperature measurement at the cylinder wall
acceleration sensor, frequency tuned
acceleration sensor, not frequency tuned
force measurement at the cylinder head bolt by the use a special washer
deformation measurement at the head of the cylinder head bolt
spark plug with a ring made of piezo ceramics
ionic current measuring method