[b]This is a side jaunt on this thread, but I've always thought the Pobjoy engines were interesting. Here's front and side views of the Pobjoy "R" engine, 90 hp, approximately 155 cid. Third shot is the internals, that's not a flywheel, it's a harmonic damper on the front of the crank. Finally, an "R" installed in, of all things, a Piper Cub.

Bill.