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Knock sensor retrofit

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Recently there was an article about killer knock which has prompted me to look at applying sensors to an engine which was not originally fitted with them. In my case to fit sensors correctly I would have to have bosses welded to the aluminium block. Having zero knowledge of knock sensors I have read that they should be high on the block but is this absolutely essential ? My cylinder head (photo attached) has plugs in the cooling tracts and my question is would adapting these to accept sensors work or is it not going to pick up the vibrations ?

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I have adapted tapped block plugs to mount knock sensors, and it worked fine for me. I would try it and see how it works.

Thanks David. Yep that would, I'm sure be an option but in this case it's an Alfa aluminium block with wet liners and there are no block plugs. If the sensors have to be on the block it is going to entail welding and machining which I'm trying to avoid so I was rather hoping that some resident expert might advise if mounting on the cylinder head would pick up the knock.


Interesting question. I've not seen knock sensors on heads, never tried it.

I can tell you noise from the valvetrain muddles knock listening when the sensor is on the block, and would likely be far worse if head mounted.

Also, what you're trying to listen to is occurring in the bore based on the crank angle and piston position in each cylinder during the window of time where you listen for detonation. Placing the sensor in that area makes sense as with a listening device, placing it closer to the thing you want to listen to will give you better signal quality, less unwanted ambient noise from valves opening and closing, valvetrain clattering etc. Knock sensors in OEM form generally seem placed in that physical window of piston motion or a bit lower than it, but I wouldn't be surprised if someone else chimed in to say they've seen them elsewhere. I have only seen placement on certain engines.

Found webinar 203 which answered all questions.

I love hearing that. Thank you.

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