Main engines U-boats.
The short story about the main engines of the WW2uboats started with basically two manufacturers having contracts with the German navy to design and build U-boat main engines with the same bore and stroke, output,revs and physical dimensions, they should be made in two execution, 6 cylinders and 9 cylinders. The 6 cylinders were destined for the VII Cs . The manufacturers were Krupp Germanische Werft (GW) and MAN (Motorenwerke Augsburg Nurenberg). The GW engines were conservatively designed having mechanical driven supercharger, Roots blower, which should only be clutched in at high output and revs. The MAN engines were very advanced for its time, having exhaustgas driven turbochargers allways in operation, Buchi system. The experience with the two types of engines turned out that the MAN type was less reliable, but had a lower specific fuelconsumption and ,if I may say, was the "Ferrari" of the two. The GW was the oldfashioned reliable workhorse, having a relatively high specific fuelconsumption. In the latter part of the WW2 the German Navy had a preference for the GWengines as ME for the VII Cs, but did not have capacity to exchange the MAN engines to GW. I guess I shall assume the majority of the main engines for the VII Cs may be GW engines allthough I have not any statistics for this assumption.
Tore