Obscure Engine sizes. Kafin, I like to keep my list of engine sizes to 049, 35's 46, and 60 size airplanes. Keep in mind that all these different size planes will all require different diameter lines, line lengths, handles, fuel, oil and nitro mixes and different size diameter and pitch props. It can start to get very expensive and the amount of different parts and hardware required to run all of these airplanes require more storage space. It can become quite overwhelming keeping track of it all. My point being, i would stay away from engines size like the 19's and try to stick to the more popular sizes.
Kevin