Sophia had 2 engines the 450-11lbs thrust and the 850-18lbs the 850 never really took of because of the KJ-66 clones RAM , both started directly off of jet-A. JPX was propane all the way.

The KJ-66 was an improved version from Jesus Artes of the Thomas Kamps-66. This is what most used as a starting point for mass production of what you know today. They were higher effiency and less weight. Sorry if I misspelled any names.