I am seriously thinking about converting my engine to propane. I have an '83 J10 and am getting about 12mpg. While not bad for a Jeep, I can't afford to do as much driving as I'd like with gas at $2.52.9/gallon. I have been looking into this for a while and have picked up a few points along the way. The biggest is to indcrease th CR to take advantage of the anti-ignition properties of the propane fuel. That and get as big a tank as posible because you don't want to run the tank dry.