DIY_EFI Digest V5 #16:Knock Sensor

[Bruce Plecan]

| If this works, maybe we could keep a library of 'knock
| signatures' by engine.

Sure seems like putting alot of effort into a dead ended subject, thou
The basic flaw with all this is that all the stuff you mention below effects
an acoustic sensor.  An acoustic sensor, is a half hearted attempt at knock
detection, since so many items can false trigger it.  Why not work on a Ion
knock detection strategy.  Something that looks for any knock on any engine,
rather then some feable side effects of detonation.
|
| There's an app note for a chip that does FFT for KS,
| but maybe overkill; if you can find the fundamental
| resonant knock freq with better than 6 dB S/N ratio,
| why look any further?
|
| On the other hand, multiple mics and holographic audio
| imaging could allow you to pinpoint not just knock to
| the individual cylinder, but maybe detect impending
| bearing failures etc. before they go catastrophic.
| What about an 'active' electronic crankshaft damper
| that attenuates 'on the fly'.

Listen for enough noises, adn the thing will always be triggering.
|
| Oops, sorry for the geek out. Anyway.
|
| I wonder what kinds of things might influence the
| knock signature? Maybe forged vs cast crank? Certainly
| aluminum vs cast iron block/heads. Maybe the intake
| manifold or headers. Aluminum flywheel? Different
| crank dampers? Would the KS change if you used filler
| in the water jackets? What about just bore/stroke
| changes? Operating temperature? Manual vs auto trans?

And most any mechanical lifter cam drives it into fits.......
Oh well.
Grumpy
|
| Lot's of questions, no answers yet. Might be it just
| doesn't matter. We'll see. Could be fun.
|
| Carter
|
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