Ray,

Both Hans (Heavy Date) and I are building Don smith B-17's, which are 138 inches in span, and generally weigh in at 50lbs or so.

Mustang,

I agree about the cooling fins having the wrong orientation for optimal effect; its probably way cheaper to produce them the way they do. By the way, I hear they are now made in China. But service is available here in the US. I understand what you say about trouble x4, and I agree, if these engines are really trouble. Thats one reason for my posting this thread: to get info from people who have experience with them. I'm considering going the way you did with the YS engines. What prop size do you plan to use?