Originally Posted by
jimandmandy
Here is some good data.
Propane Facts & Comparison Charts
You actually lose 26% of the energy content of gasoline with propane. AKI is 105, so making a dedicated engine at a higher compression ratio is the simple way to go. A turbo that only works on propane and not gasoline sounds like your complicated way to make it dual fuel.
Since "here" doesnt tell me anything about your location, is propane free where you drive? It seems like the payback for this conversion could be very long. Propane is just as expensive as gasoline in CA, so conversion is a guaranteed money loser.
That's good info, found that site but not those charts before, I'll have to do some math on that. Including your 26% enegry content figure.
Yes according to those charts there is 26% less BTU's in propane by volume where I can only assume they mean in it's liquid form. But how it's used effects overall engine efficiancy. Like the fact that you can run it at much higher pressures and leaner. Both of which increase efficiancy.
There's nothing simple about making a dedicated higher compression engine to run on propane. Certainly not from a cost or convience perspective. Where a turbo set up can be made rather cheaply with junkyard parts. I got a rather stock annemic 87 460 that could really use some more pep. I've done all I can externally to it and have pushed it to it's limits without pulling at apart. The only way I'm going to get more power or efficency out of it with gasoline is to first change the cam, which would net decent gains, or rebuild the whole thing which isn't even close to doable or cost effective for me right now. Propane has potental though, lower cost, and higher octane with a managable energy density drop. The devil is in the details though.
Propane around here is running $2.50 to $3.00/gal so with propane at $3/gal I pay the same per BTU with gas at $3.78 and can do more with the propane.