Thanks again Jeff for offering to help!!
A few nice pictures of WWI era engines I am using for inspiration:
1) Early small, compact MAN engine dating from before WWI; it would not have been used on larger U-Boats:
2) Larger 850 HP MAN Engine
3) Rival company Germaniawerft also had a large 850 HP engine. Initially, this company's equipment suffered many mechanical problems
4) Large U-139 Class's Diesel
5) Unknown WWI U-Boat engine room.
