A horizontally-opposed, two-cylinder engine, model M3. It has a displacement of 630 cc and gives 13 kW of power at 2,700 rpm. (see Kroeber, it is Kroeber & Köller).

“Koller M3”

-This engine was designed for motorgliders, and was built between 1932 and 1935.

“Koller, schematic drawings”

From Appendix 12: Köller made the M-3 engine, the only one known from this brand. It had two horizontally opposed cylinders of the boxer type. It gave 15 CV.

“Köller engine top view”