Gasoline to Propane Conversion

[shell70634]

I just added a tri-fuel system (gasoline, propane, natural gas) to my Lincoln GTX250 welder. I use it as a hurricane generator more than a welder these days. My question is does anybody know if the output, 8000 watts on gas, change when using propane? It welds just fine on either. I've read where there is a horsepower loss but will it lower the rated output?

[Winger Ed.]

Out put is basically the same, but gasoline is a more powerful fuel.
If you're not running it at max. output, you probably won't be able to tell the difference.

Like a propane car, it's OK, and propane is less 'stressful' on the engine--
but you won't be winning very many drag races.

[dverna]

Output with propane will be lower.

[Brassmonkey]

If you’re running it strictly on propane and if your engine allows you can advance the timing, because propane has an octane of 104-112 that should make up for any loss in power due to lower btu content.

[KenH]

I've got a Westinghouse 15KW dual fuel generator. With gasoline it's 15KW surge, 12 KW running. On propane it's 13,500 surge and 10kw running. If you're pulling 9 or 10 KW you'll never really know the difference between gas or Propane BUT, since propane hp is less, you will get less max KW from the generator. hp = kw

[Handloader109]

Octane doesn't increase power.... fallacy. It keeps higher compression engines from knocking. Yes, 10 to 15% less output when converting from gasoline to propane, and about 10% when using natural gas

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[challenger_i]

As stated, "octane" is less important, but BTU is key. Propane has a lower BTU rating than pump gas, so there will be a power differential. Below the max output rating, One will not notice a lack of Kw. However, she WILL burn more fuel on propane, than gasoline, Kw for Kw.
Be certain to run her on gasoline (call it once every 0 days) to keep the carb wetted up. Do keep StaBil in your wet fuel system. In your neck of the woods, alcohol-free gasoline should be available.
Be advised: if your welder is of a certain age, the valves and seats will erode more readily when running propane. Something to plan into the maintenance expenses.

[MT Gianni]

Gasoline varies a lot but averages 120-135,000 btus per gallon. LP is 91,800, Natural gas is 100,000, #2 diesel around 150,000, 3413 btu's in a Kilowatt hour.
I believe natural gas and lp are cleaner burning than gasoline. They may clear off carbon and give you a cleaner engine internally. Because things have set with the carbon you may burn a little more oil. I took care of metering and maintenance of 145 Natural Gas powered engines in the mid 80's so this is all long before electric ignition systems. Most of them were continentals and whites with a few cats thrown in.

[john.k]

Power loss is due to the gas vs liquid phase of the fuels ............when the liquid fuel is carburated ,it absorbs heat and densifies the charge into the cylinder ,propane gas does not do this ......Ive also noticed in gas fuelled trucks that the heads suffer much greater valve and seat wear and actual valve recession into the head ............One important factor is the engine must be in good condition to use gas ,other wise gas will leak into the sump ,and the engine will explode ,bulging the sump and rocker covers (if any)............Heavy duty engines often have cast iron components and will only blow out the oil filler ,breather ,and dip stick.

[Brassmonkey]

Octane doesn't increase power.... fallacy. It keeps higher compression engines from knocking. Yes, 10 to 15% less output when converting from gasoline to propane, and about 10% when using natural gas

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You aren’t wrong, but no one wanting more power would retard the timing, high octane fuel is resistant to detonation/knock from advanced timing.

[Barry54]

I saw a chart a long time ago. Basically due to differing air/fuel ratios for different fuels, the fuel occupies more or less space of the mixture. Natural gas was the worst. There was a lot of gas volume and there is less air(oxygen) going into the engine on the intake stroke.

Diesel was the winner. The entire intake stroke is atmosphere and the fuel is injected after the air is compressed.

[shell70634]

Thanx for all the input. I'll still use gasoline for regular use. The propane will be used for hurricanes. I won't have to keep alot of gasoline on hand all the time now. Propane easier to store long term.

Thanx again.
Shelly

[Winger Ed.]

During our power outages in storms, I run mine on propane. So far, it's only been for several hours or a day.
And even then, I run a couple refrigerators, and maybe a window unit AC.

It can also use gasoline, but I hope not to ever need it. I dread cleaning the carb. & fuel system to store it.
It may be over a year before I need it again, and with just propane, the maintenance during storage is quite minimal.

[SSGOldfart]

Shell70634, Sir you might want to Test Run it on each fuel with a full load (minimum of 24 hours) before our Hurricane reason starts mine used a lot more fuel with propane then Gas ? fuel is impossible to get after the hurricane gets here ,I store a extra 50 gallons in my boat yes storage of Propane is a lot easier but if you use a lot more then your going to have to store a lot more

[kaiser]

When I was a kid, every farmer in our part of the country used Propane (LPG) for home heating, farm tractors, and most farms vehicles (pick-ups, trucks, combines, etc.). I ran a car on Propane for about 4 years through my college years and still prefer LPG use with generators than "gas" because of its long term storage capabilities. On Propane run vehicles, I was told by mechanics to always switch to gas before even short term parking to avoid "drying out" the carburetor seals. The "mechs" also recommended "hard surfacing" the valves with "Nitrate" during engine overhaul because LPG did not provide the "cushioning" properties of regular gas. While vehicles lost a bit of power and fuel economy with Propane, its positive characteristics out weighed the negative IMO. The same governmental "geniuses" that have pushed the "environmental standards" on the public are some of the same ones that "killed" the much cleaner vehicle use of LPG with their regulations placed on this "clean" fuel alternative. (Then as now, it was not about a clean environment; it was about control.) LPG was considered a "waste fuel" in most "oil states" in my time, where you could see it "burned off" from oil rigs that was pumping the much dirtier "liquid gold" from the ground. (While gas sold for 29 cents per gallon "back in the day", Propane sold for 6 -8 cents a gallon - figure that at todays costs!) Solar run appliances and battery run cars (EV's) are another "kettle of fish" awaiting total government control where regulations and taxes will out weigh their usefulness; when the loss of government revenue from gasoline "peaks". Every source of power has its limitations - having control over those resources is the "key" to survival. My .02

[Handloader109]

Yeah, I'd ONLY run on propane if you can. My dad had 2 90hp Massey Ferguson tractors that were propane burners. Never had to change the oil, or sparkplugs. Never got dirty. 1959 and 1961 models that he bought used in the early 70s. Still running as my brother uses them a bit. You can easily store a weeks worth of propane for years. Not so with gasoline

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