DET cans: can't hear detination/knock when trying to purposefully induce it
 

1995 Miata NA 1.6L ("90HP" EUDM), N/A, Speeduino 0.4.4b

I made some DET cans out of a mechanics stethoscope and vacuum tubing. I connected it to a threaded hole in the block above/between the oil pressure sender and oil filter. It seems to work quite well (or so I thought), I can hear the engine really well and very loud especially at high RPM.

But then I tried to induce detonation/knock to get a sense of what to listen for for later ignition timing tuning, and couldn't hear any difference. No pinging or crackling like I've seen in example videos.

My methodology was:

Second gear pulls WOT on an uphill 1000rpm to 3000rpm
Raised ignition advance from ~25deg to 50deg in the cells between 50kpa to 100kpa in 1000rpm to 3000rpm range.

I started at 35deg. didn't hear any pinging. Then progressively raised till 50deg- still nothing. I even tried 60deg...

Any thoughts much appreciated. Maybe I should connect it somewhere else on the block? The spot seems good, I can hear oil flowing, the engine roar, lifters aren't loud.

https://cimg7.ibsrv.net/gimg/www.mia...d5040c5330.pnghttps://i.imgur.com/cfdJbtm.png