What I'm curious about is, why propane-powered engines produce approximately the same power produced relative to the BTUs of the fuel put in, as gasoline, even though the propane is already fully vaporized. Gasoline has ~31% more BTUs per gallon. If I've read your hypothesis correctly, and only ~30% of gasoline actually vaporizes and burns when it should, wouldn't we expect propane to make more power? Since all of it can burn immediately?
Propane BTUs per gallon: 95,000
Gasoline BTUs per gallon: 125,000
30% of Gasoline BTUs: 37,500
Going by this, we'd expect 3x better fuel economy and 3x more power out of an equal volume of propane.
Edit: A quick search reveals this cited chart on ResearchGate:
https://www.researchgate.net/figure/...ig18_263874565
