Non certified engines.

Okay, I don't know diddly; I've just caught the airplane bug. So, I'm
asking...

My buddy went out and spent multi tens of thousands of dollars on an
airplane engine. Lycoming, I think it was. Seems kinda pricy, but I
understand that most of that cost is testing, no iron.

I note that there was a lot of talk in the newsgroup and some books out
on Amazon.com on using non-certified engines.

How wise is that? The FAA really allows that, huh? If I had a noose in a
tree, and called it an experimental airplane, would the FAA let me fly
it? Probably not if the nose was over a populated area, huh? Just wondering.

VW engines are mentioned, I suspect because water cooled engines would
be too heavy for small airplanes, and it would introduce additional
cooling failure modes.

I guess I'm not smart enough to even know what questions to ask. So,
please discuss engines, so I can read the thread.

Is there a FAQ for this newsgroup?