Could you wire a knock sensor this way ?

[kenjamin]

Hello,

I want to hear inputs/opinion on this way of wiring a knock sensor on a Rx7 13B. 

I only have one shielded wire with 2 core wires inside running from the LINK G4X to the engine block. Now I'm thinking of running two knock sensor for each rotor housing. Is it recommended or okay to run the grounds from the knock sensors and connect it directly to the shielded sleeve that all connects to signal ground ?

 

If not, is it okay to just run 1 knock sensor on a 13B ? My train of thought is 2 knock sensors monitoring each rotor would be beneficial.

Any thoughts or opinion would be appreciated

 

 

[Adamw]

In real life it would likely work fine, but from an electronics theory perspective it is not a great option for noise rejection.

I would personally stick with just one sensor with correctly shielded signal wires, metal is very conductive acoustically and you dont have a lot of localised mechanical noise in a rotary, so you should have a relatively uniform signal-to-noise ratio on both rotors.  Examples of what I mean by "localised mechanical noise" would be say a 6 cyl with the knock sensor in the middle of the engine and a double row timing chain at the front.  The rear cylinders will be ok - you have less signal being further away from the sensor but very little noise from the timing chain way down the other end, the SNR is good.  The middle cyl is good, you have a little more noise being closer to the timing chain but better signal since the cyl is right underneath the sensor.  The front cyl is far away from the sensor so lower signal and right next to the timing chain so maximum noise = poor SNR.  

[kenjamin]

Thank you for the response!