Thanks for the link Scota, that's a pretty good price...

I actually purchased two of them this fall at the Hayward CA store for $54 each (new in the box), but someone broke into my van and stole them before I had even opened the boxes.

Then I bought a couple used ones off eBay, but one of them had some of the parts of the propane system fiddled with and some parts broken and missing.

These engines look pretty good, but the parts are not as nicely finished as they are on the genuine Subaru EH025 engines. I have no specific reasons to think so, but I doubt that these engines are any different inside than the gasoline engines.

An engine running on propane produces about 2/3 the power as it does on gasoline - provided you have upped the compression ratio and advanced the ignition timing. As these are a four stroke (heavy), and you would also have a heavier fuel tank than with gasoline (plus a regulator), I don't think propane has much promise in an airplane conversion.