You said that LPG burns hotter than gasoline. My gut reaction is that this is incorrect, but I am unsure of the actual result. As you get more complex hydrocarbons, I believe you get higher flame temperatures. Thus if this thinking is correct, the gasoline will have a greater combustion chamber temperature. Where this might be incorect, is if the propane, in its vapor state, may mix with air better than the gasoline in its liquid state. Thus the fuel/air mixture with LPG may burn better. However I have had one experience with a gasoline to LPG conversion, and I thought you took a horsepower reduction because of the lower BTU value of the propane versus gasoline.
Does someone have a textbook website handy to answer these questions?
Now if you asked me the diference between propane and natural gas, I could give you a confident answer immediately.
dwedel