[Bill S]

Friend of mine has an older BMW he put a turbo on, and told me there is info out there on making an engine knock sensor for tuning. It uses a cheap hearing aid connected to a long wired headset.
You drive and listen for knock.

Anyone hear if this ?

[Jack Gifford]

Would the hearing aid need to be solidly attached to the engine block, as an OEM knock sensor is?

[krisr]

Originally Posted by Jack Gifford

Would the hearing aid need to be solidly attached to the engine block, as an OEM knock sensor is?

Kinda sorta.

https://www.haltech.com/product/ht-0...nock-ears-kit/

Most tuners use something like these ^^.

The knock sensor is bolted to the engine block and wired to the interface box which then converts the knock signal into an audible signal that you can listen for with noise cancelling headphones.

What i've also seen done is rather than use headphones, use an output from the ECU to trigger an LED light on the dash when knock occurs - but generally where you see knock on a street car, pull that amount of timing out if it's consistent +1-2 degrees extra for some safety. That is all dependent if you're using a computer to control timing across an RPMxMAP style table. If you're using a distributor, then just alter the curve and hope for the best

[steve25]

The firing order should also dictate where you place the sensor/ pickup on the block to listen for danger.

Since 5 and 7 fire consecutively they tend to rob fuel from each other and run leaner then the others, so these two cylinders will start to ping or knock first 99% of the time.