The Jumo 206 was intended as a replacement of the Jumo 204 and was based on the Jumo 205. The bore/stroke ratio of the 206 was reduced by 20% and at the same time, the volume was increased by 30% against the Jumo 205. The developement was started in late 1936 / early 1937. Major design problems arised from the intake ports of the air charger an enlarged version of the Jumo 205. The Jumo 206 offered 60% additional ground power than the Jumo 205. However, it was not able to keep this power surplus for longer than a few minutes. Several prototypes were built between 1937 and 1940, but finally the Jumo 206 design was stopped in 1940 it was continued under a new concept as Jumo 208.
Aircraft Types equipped with Jumo 206:
Junkers Ju52 3mho
Two Ju52 (D-AJYR and D-AQAR) were equipped with Jumo 205C-3
for experimental flights. Later the center engine was changed to Jumo 206A.
No further aircraft were equipped with the Jumo 206.
Further reading at other Sites:
Multi-crankshafts opposed piston engines (several facts of Jumo 206)