Megasquirt ems

Just reading but a Det Can seems very effective means to listen for knock. Basically a 3/4" copper pipe with a cap on one end and the other end pounded flat with a hole in it to allow it to be bolted to the block. The end with the cap has a hole drilled to insert a heavy rubber hose which can be fairly long connected to a pair of muffle type hearing protectors. Run the hose into a "Tee" and then the two hoses into holes drilled in the hearing protectors. Making it a stethoscope that surpresses surrounding sound. Seems simple enough.

Here's link of a similar one, but the idea is the same.
http://forums.neons.org/viewtopic.php?t=295450