I was shocked to find i got 5mpg on propane on a recent trip with my new-to-me 1973 w/454, avg about 60-70mph. Is that about right for a 23footer? I'm new to RVing, but still shocked. Thought propane was supposed to be better--i guess just cheaper, not more efficient (well, cleaner). Thanks. I suppose i could check the timing advance. It's got a new air filter, new plugs/wires. Points/distributor/rotor are longgggg overdue.

You must have been going uphill both ways!

Propane has less BTU content than Gasoline and will come up shorter in the MPG avenue. While it may burn cleaner and is cheaper per gallon, it doesn't get the same or better MPG as a Gaso unit would.

quote:

Originally posted by Bill N.Y.:

Propane has less BTU content than Gasoline and will come up shorter in the MPG avenue.

Yes, but you don't have to change oil as often.

In the early 70s, I had friends with propane Class As. Geeze, I had forgotten about the eminently forgettable Commanders. They raised their compression quite a bit, changed cams and got more power and some mileage back. They never took long trips without careful planning re fuel availability. At that time, they paid no road tax on their fuel. There used to be something called the Propane Vehicle Challenge, and all sorts of people were building very powerful, economical engines to run on propane. The dragstrips seemed to always have at least one propane car doing well. I don't know why propane never got more popular. Probably tank size and supply issues.

I think there is more to a good propane conversion than just bolting on a carb replacement.

Why are most propane Barths in Canada? Is propane a better deal than gasoline?

Propane is 130 octane. This is the reason you can inject it into intake of a diesel without all kinds of precompustion. Injecting the diesel fuel which ingnite and that ignites the propane. Anyway if you are going to do propane right you need to make a propane engine. This means very high compression ratio, cams, ignition etc.

In the good old days Minneapolis-Moline farm tractors made the same tractor in three versions. Diesel, gas and propane. The propane engine produced more power and less fuel than the other two versions. I spent many an hour on one of the tractors.

Many years ago, a fellow up in Canada make a 454 chev into a propane engine and reported increased power and economy. At 13 or 14:1 compression you are able to utilize the high octane.