Stacked knock sensors for monitoring.

[dkw_dude]

Hi
I'm considering installing extra knock sensor(s) for listening purposes, and wonder if I can just take a longer bolt and stack two sensors.

And if the tightening torque should be increased as I think (?) the force will distribute over the sensors? I'm thinking twice the torque, opinions?

I don't want to electrically splice into the existing ones and attenuate the high impedance signal. I also won't bolt the sensor to a random place on the block, the signal might not be the same there.

[newsh]

I think it will work
Torque should be the same

[S2central.net]

Should work indeed - a knock sensor is basically a microphone and the ECU does a bunch of filtering (analog and digital) to detect if knock signals are present.

[K Simmonds]

It'll work but I don't think you want to use twice the torque, as Newsh says it should be the same as stock, 20 NM. I'd be wary of winding an M8 bolt up to 40NM, one long enough for two sensors would probably start to stretch.

[UrS4boy]

G61 and G66 Knock Sensor info

Umm....The 3B, AAN, ABY and ADU already have 2 knock sensors to handle the "listening" (for predetonation) requirements.

Why would you want more?

G61 and G66 Knock Sensor info:

http://forums.quattroworld.com/s4s6/msgs/21047.phtml

[dkw_dude]

Thanks for the advice and information guys, good point regarding bolt torque.
The reason why I want to do this is because I'm running Vems and have connected the knock sensors to an auxiliary amp and headphones, but recently I upgraded the Vems firmware to make use of the knock sensors. I still want to be able to listen "by ear".

[Error404]

By ear it won't really matter where you install the sensor. There are plenty of spare bosses on the block to use.