Hello; I have just enough engines, until I see something I like, then I need one more. My wife understands. When I was a windsurfer, I had to have 8 of them and at least 12 sails. When I was into motorcycles ( still am) I had to have at least 5, One alone would never do. How much is too much? I don't know. I know how much is enough, but that's a moving target. I try to avoid counting how many engines are sitting on the shelf, the thinking is that I'll have enough parts for my running engines, no matter how many I crash.