Propane vs gasoline - how much fuel?
Propane vs gasoline - how much fuel?
(OP)
I own a small fleet of trucks with 454's. I am considering converting them to run on propane. Now, I know propane has less BTU's per gallon than gasoline. How much more propane is needed to go the same distance as gas? Right now, for example, gas here is about $2.10/gallon and propane is still at $1.85. Is it still cheaper to run propane?





RE: Propane vs gasoline - how much fuel?
calorific value is 46.3 MJ/kg
gas is .74 and 42.7 respectively.
You'd be losing money hand over fist. Propane has to fall below 80% of the price of gas, per gallon, to break even.
Cheers
Greg Locock
RE: Propane vs gasoline - how much fuel?
Now if you were to have engines optimized for propane (12:1 compression), you would gain quite a bit of mileage/BTU, and power, which would make it worth it for sure.
RE: Propane vs gasoline - how much fuel?
RE: Propane vs gasoline - how much fuel?
In Texas, you will pay an annual State road use tax based on vehicle weight and estimated miles driven. For a 4000 lb vehicle at 10,000 miles, you will pay the about $85 USD, then a Federal imposed price per gallon of 13.5 cents.
http://www.window.state.tx.us/taxinfo/fuels/lg.html
Then at 162.305:
http://www.capitol.state.tx.us/statutes/docs/TX/content/htm/tx.002.00.000162.00.htm
With the prices of gasoline soaring, LPG is competitive, pity there arent many autos taking advantage of it. The EPA has strict guidelines on vehicle conversions, tailpipe emissions, and the general public demands bullet proof conversion systems, something which the OEM's tried then finally gave up on. There are a very few GOOD aftermarket systems that perform well, and these are NOT the old bolt on yourself systems. Conversions now cost around $6500 USD, which buys an EPA compliant system, multiport fuel injected and OBD II compatible.
Franz
RE: Propane vs gasoline - how much fuel?
You'll have to save a huge amount on fuel to pay for the valve jobs, IMO.
RE: Propane vs gasoline - how much fuel?
Regards
pat pprimmer@acay.com.au
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RE: Propane vs gasoline - how much fuel?
A properly set up engine, compression, valve timing, and ignition system, will show no adverse reaction to using propane as a motorfuel.
Franz
RE: Propane vs gasoline - how much fuel?
I presumed correct tune.
I hate dual fuel conversions for that reason, and I really like the idea of going to forced induction at the same time as changing fuel, so you optimise the use of the 104 octane, and get both an economy and performance boost.
I really wonder that when car companies make Taxi specials with factory LPG, why they don't put in big tanks, one fuel only and high compression head or pistons (say 11:1) so that they can tune to optimise the result from the fuel.
Maybe they do elsewhere, but they don't here. Our LPG is an inconsistent mixture of Propane and Butane, so 11:1 is about as high as you could go with the worst brew you might get.
Regards
pat pprimmer@acay.com.au
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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.