breezinup posted:I'm not an expert, but trying out an engine on a certain size curve probably isn't going to hurt anything. If the engine slows down noticably due to the flanges rubbing on the rail, then the radius is too small. You may hear it as well. Also, Lionel seems to be conservative on their recommendations (remember, they're only recommendations, not necessarily absolutes). For example, operators will report that an engine with an O54 recommendation runs fine on 042.
However, going from an 042 recommendation to 031 may be stretching it. And just because the Lionel version is "based on" the K-Line version, even if true, that doesn't mean there weren't significant changes made by Lionel. The phrase "based on" doesn't provide any detail as to the degree of sameness.
You'll just have to try it, but as a guess O36 might be an absolute minimum. I have an engine that says 036 minimum, and it will not run on 031, so sometimes, at least with smaller radius track, there's no wiggle room.
Agree, you HAVE to try it before you buy it, I agree O31 might be a bit tight but only one way to find out, unless someone has tried that specific setup.
