As it actually is rather few photos I've taken I'll start hard with the remarkable JUMO Diesel(!) aircraft engine:
It's by two stroke principe and the remarkable design lies in two cranckshafts with a ray of six cylinders in between - Causing the pistons to oppose each other and compress/combust when closest in the middle of the cylinder :-o
As valveless two-stroke, the inlet ports (exposed by the one row of pistons when 'in bottom') is situated in the one end of the cylinder, and the likely exhaust-ports in the other end making the flow of the inlets fresh air (as well as the transport of exhaust-gasses) easier to controll.
Try understand the principe at the cut-away picture.
The engine was actual rather popular - as it was used in post-war Soviet tanks as well as in the British Chieftain-tank.
Edited by Armand, 18 July 2017 - 07:14 PM.