Propane was used in the 50's and 60's because it was dirt cheap and burned so much cleaner. However, it really was low power. I remember a fleet who ran Intl R190's with RD450 engines converted some of them. They took the propane off because no one would drive the converted ones for lack of power. If a 450 cu in engine has lo power with LP, what would one expect from a smaller engine. Up until the 80's or so propane distributors used LP powered delivery trucks. Now they are almost all use diesel. Must be a reason.
