Searched youtube about the Clem engine and came across this turbine by Joe Holden. Doesn't sound like overunity but sounds very efficient which is a start.
Talk about the device starts around 3:14 in the video.
https://youtu.be/5lojoKUM8Z4
Was hoping the above video was recent but it may just be an old repost? Here's another one which looks old. Don't know if he is still with us?
https://www.youtube.com/watch?v=3j-O3rfw5c0
Nice video series on him.
https://youtu.be/MDVSEwLs07s