RE: OS .40 LA
The LA series engines are great all around engines. They're easy to tune and seem to last forever. I have 4 .40 LA's, and I beat them up pretty good. I've never broken one. I use them when I make my SPAD planes. Some fly, some just "Fall with style". For a trainer or small sport plane, (something that's going to crash a couple times) you can't beat them (literally).