what I know... It's German
the data plate is incomplete which says to me that it may have been a prototype
manufactured either before or during WW2 because the Gebr Becker plant was shut down
for several years after the fall of the Reich and reopened under a different name
it seems to be designed for aircraft because of the high quality fit and finish and the spline drive

it is modeled after a radial aircraft engine except the number of cylinders is even
most of the German words on the unit I was not able to translate into english
what the hell is this?
I can find no info after many long hours of searching

no it has a spline drive and it is a compressor
I had one of the heads off and it has a steel sleeved cylinder and a little piston