I'm interested in it for a few reasons: it stores indefinitely, it burns cleanly, it's pretty cheap, and it's got a high resistance to detonation so I can bump the CR on a purpose built engine. CNG is another less desirable choice, but availability around here is limited to two fueling stations in the whole state unless I want to build a home filling station for a few thousand bucks.
I know there are a few stumbling blocks, like startup enrichment, low ambient temperature operation, and lower energy density. I'm hoping a flexible SFI unit can deal with most of this. FAST has hinted at plans for propane with it's XFI line, but since I've pestered them, have received nothing but a 'look for an announcement soon'.
Has anyone experimented with or used propane long term, carb or EFI?