For R&D purposes, I need to create a knock sensor signal that approximates pinging on an engine.

Would hitting the block with a hammer simulate this? Also, how important is the internal rotating assembly to the resonation frequency of the block? Could I leave those bits out for a "research block"?

The goal is a cheap knock sensor output device. I want to filter out as much of the running noise as I can, but still let pings get through.

-=Russ=-

 

they tell you to hit the engine with a hammer in the fsm, i dunno if its realistic, or just a dumb test to see if the system does something.

if you want a cheap knock sensor, find a factory one, all the turbo cars have it, the 87-88's even have an external knock control unit....

 

I may be wrong but the way I understand pinging, it is the sound of pressure reverberation inside the combustion chamber. The pitch changes as the combustion chamber gets larger.

The pitch would be related to the speed of sound at that pressure and temperature inside the combustion chamber.

A hammer strike will excite a knock sensor but only because the sound is across a very large range. I do not think it's sound is representative of a real ping.

ed

 

Hm.

I'm learning, through my research, why proper knock sense units are so expensive. They're not at ALL trivial - tie in crank angle, RPM, and a bunch of other stuff.

What kind of outputs do the external knock control units put out?

-=Russ=-