Converting Diesel (or Gas) Engines to Propane/LPG - Diesel Truck Forum -
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post #1 of 3 (permalink) Old 03-31-2008, 02:46 AM Thread Starter
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Converting Diesel (or Gas) Engines to Propane/LPG

Can you convert a diesel (or a gas truck) to run entirely off of propane/lpg?

If so, what are the ups and downs of doing so?

What kinda fuel economy ya gonna get?

What would be the effect on get-up-and-go-power?

Had a family friend a looong time ago back in TX that converted his old truck to run entirely off of the stuff, but can't remember for sure if it was gas or diesel.......the fella also built his own airplane with only the occasional help of a buddy that was drunk half the time.......point being, the fella was mechanically/mathmatically smart as all hell and coulda probably made the truck run off of anything he wanted to.....I ain't that smart so I need some advice on the subject!

Thanks for any help ya fellas got to share!
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post #2 of 3 (permalink) Old 03-31-2008, 03:36 AM
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The conversion is gas to propane or dual fuel - gas and propane with a switch.

Mount a DOT propane tank with the high pressure fuel gas fuel line to the sut off solinoid and on to the regulator, from the regulator a large low pressure hose to the carb or adapter.

Propane is high octane ( I think 120 ) and picky about the ratio. It will not fire with the mixture off by very much. The compression ratio can be upped a lot for a propane only engine, as can the spark advance.

There is about a 10% loss in fuel mileage on propane with a dual fuel but the changes in a propane only engine can give 10% better with propane - it just won't be easy to go back to gas for fuel.

My uncle bought propane for $30 a thousand gallons at the refinery in the early 50's so there was a real saving in cost of fuel. The down side was that it cost about 4 engine overhauls to do it right, At that time you could get an overhaul starting at $150 and for propane $340 and the kit was $400. Today kits start around $1200 and many engines will run as is but the propane starts at $2.50 a gallon and here they add a tax sticker for $128 a year last I heard so most went back to gas. Not a lot of difference between an electronic fuel injection with unleaded and propane.

For diesel, propane supplementation contributes a catalytic action at low ratios and can be used at stronger ration as just more fuel with a lower EGT, much the way that methanol/water works. Spray it in with boost and get lower EGT with higher HP numbers. They work as long as the ratio remains below the mixture needed to fire by compression.


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post #3 of 3 (permalink) Old 03-31-2008, 02:05 PM Thread Starter
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thanks a ton for the info and the clarification, much appreciated
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