Bruce
01-18-2004, 10:38 PM
The knock sensor has a chip of material in it similiar to quartz. Yep, just a type of rock, in simple terms. It's neat property is that, as you squeeze it, it generates a little electrical pulse. If you design the holder correctly, then you can in effect rattle it in such a way that it gets squeezed, and gives off that voltage. Now, if your looking for a rattle at a particular frequency, you can design a filter to look for that specific tone.
The sudden pressure rise that occurs with detonation, takes and rattles the piston in the bore. That *rattling* sound of detonation is in fact something rattling.
The only down side to all of this, is that it's frequency sensitive. So any noise of the right frequency can set it off. **OR** if you do something to alter the sound generated. Too much fuel, and or too much timing, can alter the frequency *just* enough *sometimes* that you'll do the damage without triggering the Sensor.
The other problem is that preignition can be silent, and the Knoc sensor can miss that all together.
While the Knock Sensor is pretty well designed and does a good job on a stocker as you raise the HP level you need to develope the other tuning skills so as to not totally rely on the Knock Sensor as being your only way of seeing your motor is detonating.
Welcome to the world of plug reading........
The sudden pressure rise that occurs with detonation, takes and rattles the piston in the bore. That *rattling* sound of detonation is in fact something rattling.
The only down side to all of this, is that it's frequency sensitive. So any noise of the right frequency can set it off. **OR** if you do something to alter the sound generated. Too much fuel, and or too much timing, can alter the frequency *just* enough *sometimes* that you'll do the damage without triggering the Sensor.
The other problem is that preignition can be silent, and the Knoc sensor can miss that all together.
While the Knock Sensor is pretty well designed and does a good job on a stocker as you raise the HP level you need to develope the other tuning skills so as to not totally rely on the Knock Sensor as being your only way of seeing your motor is detonating.
Welcome to the world of plug reading........