LP Gas Conversion of 2-stroke crossflow

[A Fn Noob]

Ive done a little bit of reading and wanted to get opinions from you guys about the feasibility of converting an OMC '76 V4 crossflow 135 to operate on LP gas.

I am wondering what the easiest and most effective way to lubricate the engine would be. A VRO pump from a later model engine?

Also, what specifically would be involved in increasing the compression ratio to account for the higher octane levels of LP?

[riverrunner114]

not trying to be rude, but why would you want to do this?:confused:

[David]

1. You get less power with propane than gasoline because it enters the cylinders as a vapour and displaces air.
2. You likely can't run more compression because you won't have the cooling effect of fuel evapouration. Your engine will run hotter and will be more prone to detonation. 20 years ago I blew up a few 4 stroke propane engines at high rpm. Then we bought Kistler probes and started seeing all the detonation. Two strokes would be worse as there is no 'cooling' stroke, ie it fires every rotation.
3. Even VRO just adds oil to liquid gasoline. With propane you would have to mist the oil in somehow.

I'm not trying to be rude either and I wish you well. Maybe you can prove me wrong. I haven't worked on propane engines in 20 years.

[BenKeith]

How do you plan to get a 50:1 fuel/oil mixture???? That's gonna be kinda hard to do when propane is a gas when it comes out of the vaporizer/converter and oil is a liquid. I guess you could use a high pressure injection system that would atomize the oil and then control the amount being injected but seems like a lot of high dollar engineering to do that.

As already mention, all that to reduce the preformance of the motor because propane will not make the same horse power as gasoline and as also mentioned, how you gonna cool the back side of the piston dome like the gasoline does, there ain't no oil in an oilpan being slung up their to replace the gasoline that's doing that.

[A Fn Noob]

First, Im not hell bent on doing this, but I think its worth thinking about. LP Gas is tax free, Carbon free!

Now Im no tree-hugger but the big corpoprations have no incentive in developing or releasing technology to retrofit old carbureted 2-strokes to run more efficiently. In fact, they try their damndest, imo, to supress such activities. It goes against their business model. But thats for another discussion.

I was just exploring the idea of using LP, high pressure liquid that vaporizes when the pressure is dropped slightly, to atomize oil that is metered by the pulse of the engine.

I have read that the direct injection of cng does not have the "displacement problem" and also eliminates carbon, and that LP has similar properties to high octane gasoline. The cooling is a problem in air cooled machines, but not as bad in water cooled machines, and can be compensated for in both.

I dont have a long history of being interested in engines, but I think that these old outboards are worth keeping around. Not everyone can afford a new or even new(er) outboard. And Im not hanging some 500lb Jap motor on my boat.

And forgive me if I ask a dumb question, Im a Noob. I think this forum is great though, lots of very knowledgable people here.

Here is a page that I derived some useful information:

http://www.envirofit.org/files/publications/BAQ%202002%20Direct%20Injection%20as%20a%20Retrofit%20Strategy.pdf

It talks about a set of 1800hp 2-stroke nat-gas engines that have been in near-continuos operation since the 1940's.

I think LP gas or CNG could be better than that $h1% they are peddling at the gas pumps.

[riverrunner114]

First, Im not hell bent on doing this, but I think its worth thinking about. LP Gas is tax free, Carbon free!

Now Im no tree-hugger but the big corpoprations have no incentive in developing or releasing technology to retrofit old carbureted 2-strokes to run more efficiently. In fact, they try their damndest, imo, to supress such activities. It goes against their business model. But thats for another discussion.

I was just exploring the idea of using LP, high pressure liquid that vaporizes when the pressure is dropped slightly, to atomize oil that is metered by the pulse of the engine.

I have read that the direct injection of cng does not have the "displacement problem" and also eliminates carbon, and that LP has similar properties to high octane gasoline. The cooling is a problem in air cooled machines, but not as bad in water cooled machines, and can be compensated for in both.

I dont have a long history of being interested in engines, but I think that these old outboards are worth keeping around. Not everyone can afford a new or even new(er) outboard. And Im not hanging some 500lb Jap motor on my boat.

And forgive me if I ask a dumb question, Im a Noob. I think this forum is great though, lots of very knowledgable people here.

Here is a page that I derived some useful information:

http://www.envirofit.org/files/publications/BAQ%202002%20Direct%20Injection%20as%20a%20Retrofit%20Strategy.pdf

It talks about a set of 1800hp 2-stroke nat-gas engines that have been in near-continuos operation since the 1940's.

I think LP gas or CNG could be better than that $h1% they are peddling at the gas pumps.


not to be a stickler, but propane is C3H8.. and guess what the 'c' is? allbiet, propane does burn cleaner than gasoline and being tax free would help, but here in Texas and most of the US that I am aware of, boat gas is tax free as well, at least the 43 cents road tax they are charging at the pumps... and on that subject so is the gas for your...everything else but your car.. road tax free....lawn mowers(yard equp), four wheelers, farm equip, etc, etc... I have the form for getting a refund somewhere in here but don't have time right now to dig it up..easy to find.. google 'gasoline road tax refund' you do it once a year... good luck, john

[marshan162]

The only way I can see you converting a 2 stroke to run on LPG at home wporkshop level, would be to run the motor on a mix of LPG and Gasoline, say 25% Gasoline and 75% lpg. You would need to reduce the jets for the Gasoline to 25% of normal flow and change the oil mix to 10:1. That way you would in theory get the same amount of oil in the motor. But wether this would still provide enough cooling effect, I dont know and I'm sure there would be other problems to resolve

If your main goal is to produce less CO2, there would be no advantage as LPG produces about the same CO2 as Gasoline. In the US I don't think the cost savings would be worth it. In the UK Gasoline is about $8/UK gallon and bulk LPG is about $2/UK Gallon, so in the UK there would be a bigger saving.

Although the debate still runs, the only way to reduce CO2 emissions significantly is to run ethanol. Ethanol still prodeces CO2 but beacause Ethanol is produced from crops the CO2 produced by the motor goes back into the crops for the next batch of Ethanol.

The only sure way to reduce CO2 would be to have a Human culling program, but I don't know of any politians brave enough for that one.:o

[riverrunner114]

The only way I can see you converting a 2 stroke to run on LPG at home wporkshop level, would be to run the motor on a mix of LPG and Gasoline, say 25% Gasoline and 75% lpg. You would need to reduce the jets for the Gasoline to 25% of normal flow and change the oil mix to 10:1. That way you would in theory get the same amount of oil in the motor. But wether this would still provide enough cooling effect, I dont know and I'm sure there would be other problems to resolve

If your main goal is to produce less CO2, there would be no advantage as LPG produces about the same CO2 as Gasoline. In the US I don't think the cost savings would be worth it. In the UK Gasoline is about $8/UK gallon and bulk LPG is about $2/UK Gallon, so in the UK there would be a bigger saving.

Although the debate still runs, the only way to reduce CO2 emissions significantly is to run ethanol. Ethanol still prodeces CO2 but beacause Ethanol is produced from crops the CO2 produced by the motor goes back into the crops for the next batch of Ethanol.

The only sure way to reduce CO2 would be to have a Human culling program, but I don't know of any politians brave enough for that one.:o

CO2 is CO2 no matter where it came from...from ethanol or from anywhere else ... its still CO2...just because it came from crops dont mean it goes back there...:confused: :confused: :confused:

[BenKeith]

Yes they burn cleaner than non converter gasoline engines but they do not run clean enough to meet current EPA quidlines. New propane engines have the computers, oxygen sensors similar to gasoline engines.

Another problem is not all propane is the same, there are different grades, much of which is an industrial grade and causes all kinds of problems if you try to burn it in internal combustion engines. You would need a source for at least G5 propane to run in your motor. Propane might burn cleaner but it's nasty as hell getting to the combustion chamber and creates all kinds of carbon problems in the lock-off valve, converter/vaporizer and mixer (carburator). I've had to pull many intakes off and chisel the carbon out where it built up to the point in had the motor choked down. Many of the current IC engines running propane even have thermostats in the fuel delivery system so the fuel will be delivered at a high enough temp to help keep that sludge from building up in the converter and passed on into the engine. You will also need a fairly good heat source, hot water or some type of heat sink on the exhaust to keep the converter from freezing up. An outboard cooling system will not make enough water temp quick enough to keep the converter from freezing into a solid block of ice, quit working and shutting the motor down for lack of fuel.

If you're comlaining about fuel mileage now, wait until you start running propane, it will drop about 25%.

These are just a few of the obsticals you will need to address.

[marshan162]

CO2 is CO2 no matter where it came from...from ethanol or from anywhere else ... its still CO2...just because it came from crops dont mean it goes back there...:confused: :confused: :confused:

Yes it does

Where does the Carbon in a plant come from?
Answer :The Co2 it takes in

What comes out of the plant?
Ans: Oxygen. Co2 with the Carbon missing = Oxygen

If you grow wheat for the purpose of making ethanol, the weight of the wheat is proportional to the amount of Carbon removed from the atmosphere

The main purpose of ethanol as a fuel is nothing to do with clean or poison free air. The purpose is to remove the green house gas Co2

All basic chemistry

[j_martin]

To add CO2 to a greenhouse, you just burn whatever gas is available, natural or propane.

http://www.johnsongas.com/industrial/CO2Gen.asp

Ethanol in the fuel supposedly reduces the unburned hydrocarbon component of the exhaust, ie Carbon Monoxide.

John

[riverrunner114]

Yes it does

Where does the Carbon in a plant come from?
Answer :The Co2 it takes in

What comes out of the plant?
Ans: Oxygen. Co2 with the Carbon missing = Oxygen

If you grow wheat for the purpose of making ethanol, the weight of the wheat is proportional to the amount of Carbon removed from the atmosphere

The main purpose of ethanol as a fuel is nothing to do with clean or poison free air. The purpose is to remove the green house gas Co2

All basic chemistry

he he he... I know that plants use CO2 and convert it to O2... what I meant was that just because this particular pound of CO2 came from burning ethanol doesn't mean that it is going to travel to nebraska to be returned to the farm that the corn or sugar cane was grown..The crops are going to take in the co2 that is avalible to them, regardless of where the co2 came from originaly. and as far as simply knocking the carbon off of CO2 and leaving the O2 is a little more complicated than basic chemistry. when 6 molecules of water and 6 molecules of carbon dioxide go thru the Photosyntesis process in a plant you end up with one molecule of sugar and 6 molecules of oxygen, with sunlight being the energy source. And that is really over simplified. written out it looks like this..

6H2O + 6CO2------> = C6H12O6 + 6O2...basic chemistry. The plant is carbon based way before this process begins..

And in my opinion the main reason for using alcohol based fuels is to get out from under the thumb of foreign countrys that have oil...but until someone puts a bullet in the head of 'big oil' in this country that ain't ever gonna happen. how many billions did exxon profit last year.. I forget now.. but they are not interested in major changes at this point. what we need is a president and a congress that owns a bunch of farms instead of a bunch of oil wells... then maybe some changes will be possible...Dont let anyone fool you, everything is about money. When I was senior Lab Tech at Scott Speciallity Gases for 6 years, we released more CO2 to the air than you can imagine...all because we had a permit that we 'paid' for...If the government wanted to do anything about greenhouse gases, they would, and most of it would be fairly simple to do... but, oil companys have a lot of money and the people that run our government have a lot of oil.. vicious circle jerk and we are the ones in the middle

one other thing, if we used H2 (hydrogen) as a fuel source the only by product is water... no CO2.. no CO..no NOx... and in big citys like houston, the Nitric Oxide is the big nasty.. its the brown haze that you can see over the city for 75 miles away...and extremly nasty

[j_martin]

And in my opinion the main reason for using alcohol based fuels is to get out from under the thumb of foreign countrys that have oil...but until someone puts a bullet in the head of 'big oil' in this country that ain't ever gonna happen.

The main reason the oil companies put alcohol in the fuel is that it is a damn cheap octane booster, about 130 octane. They can then get rid of a lot of scrap chemicals in the gas that lowers octane. Ever notice how gas stinks, and is highly variable lately.

Back in the 80's, "the arab oil crisis", I was quite heavily involved in small scale ethanol production. There are some things to overcome to burn it in ordinary engines, all of which are relatively easily remedied. You haven't been able to sell a car in Brazil since about the 70's unless it'll run on ethanol, and none of the car companies missed a sale. Many of us had carb'd cars set up to run it right out of the still, at 10% water. They screamed and they got good mileage. When we got close to coming up with a closed loop system on the farm, grow the corn, make the fuel, use the fuel, put the waste back into the farm as feed or fertilizer, thus cutting out the oil companies, our free still licenses suddenly got taxed out of existance.

Ethanol, wind energy, etc, all got politic'd out until the big interests got into it. Then it's the cat's meow.

Alcohol is now a big corporation deal, and the farmer still rapes his land for peanuts to supply the fodder for it. Hydrogen is cumbersome and dangerous to handle, making it automatically a highly regulated big company deal.

What a mess. I think I'll play with my boat and go fishin' before I lose my mind.

[riverrunner114]

Quote:What a mess. I think I'll play with my boat and go fishin' before I lose my mind.

I hear ya brother, the bad news is we're all gonna die anyways, might as well go boat ridin and enjoy the time we got:)

[A Fn Noob]

Ok, f*** it! It was just an idea I was toying with. A learning experience nonetheless. The thing that got me looking into it was all the stuff Ive been reading lately about how the fuel at the pumps will kill old two-strokes.

A few years ago I converted my generator to LP after losing a needle in the dark cleaning a gummed up carb during an ice storm. Best thing I ever did.

There's not a lot of info out there on LP conversions of 2-strokes, but some of the info I did find related to outboards...Mercury, Orbital, Synerject all seem to be doing a lot of research on 'gaseous' fuel injection, and theres an assload of patents recently by the Japanese related to 2-strokes and LP/CNG, probably aimed at motorcycles, but not specific.

[marshan162]

he he he... I know that plants use CO2 and convert it to O2... what I meant was that just because this particular pound of CO2 came from burning ethanol doesn't mean that it is going to travel to nebraska to be returned to the farm that the corn or sugar cane was grown

I'm not saying the Co2 molecules wander all the way back to the original farm they came from either, thats just stupid. But the ongoing process of growing vegatable materials to produce ethanol removes the Co2 that is produced when the ethanol is burned. Its what is known as a 'Carbon nuetral Fuel' its a complete cycle. Overall it is about 70% of totally carbon nuetral

The plant is carbon based way before this process begins

So where did that carbon come from? It came from the Co2 in the atmosphere

one other thing, if we used H2 (hydrogen) as a fuel source the only by product is water... no CO2.. no CO..no NOx

Only OK if you produce the Hydrogen without producing Co2. This means Solar, wind or water power. No good if you burn oil to generate electricity to do it.

[riverrunner114]

Quote:....So where did that carbon come from? It came from the Co2 in the atmosphere





jokin right? carbon based plants get their carbon from co2??? :) top right side... "C"...carbon...the thing that everyliving thing on this planet is based on...

but I think we have kinda drifted away from the origin of this post...

[marshan162]

From a seed to a tree, whats the difference, lots of carbon. Where does it come from Co2

[riverrunner114]

From a seed to a tree, whats the difference, lots of carbon. Where does it come from Co2


CO2 gets its 'c' from the same place everything else does(including plants)...carbon

[j_martin]

riverrunner

Photosynthesis is the process by which all green plants convert the carbon in atmospheric carbon dioxide to carbon compounds used by the plant, releasing the oxygen to the atmosphere in the process. The source of all the carbon in plants is the atmosphere. You can grow plants in a hydroponic soup that contains no carbon at all.

So the source of all the carbon in a tree is actually atmospheric carbon dioxide.

hope it helps.

ps. I am American so I have the right to be wrong, but I never exercise that right. :D

[riverrunner114]

Quote: ps. I am American so I have the right to be wrong, but I never exercise that right. :D

he he ...I like that part...now your starting to sound like me... I thought I was wrong once, but turns out I was misunderstood:) ...

no disrespect was ever meant, now that I don't have a wife anymore, I don't get the chance to argue nearly as much as I did....hey... wait a minute.. thats a good thing! And truthfully as to where it goes and where it came from don't mean a hill of oxygen producin beans to me any more...don't make me boat no faster. worry'n over gases used to consume a large part of my day back when I was a member of the real job clan... so it don't put no money in me britches anymore either...now days I just sell boat parts, mostly steerin parts and play with the 3 year old as much as possible...

so whats a boat lovin american doing on the wrong side of the ocean? I hear its cold and damp over there and gas is even more expensive...

anyhoo, fixin to get me arse in gear and go see mom for thanksgiving... you boys have a great holiday, even if its a long ways from home:)

john
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[marshan162]

riverrunner

Photosynthesis is the process by which all green plants convert the carbon in atmospheric carbon dioxide to carbon compounds used by the plant, releasing the oxygen to the atmosphere in the process. The source of all the carbon in plants is the atmosphere. You can grow plants in a hydroponic soup that contains no carbon at all.

So the source of all the carbon in a tree is actually atmospheric carbon dioxide.

hope it helps.

ps. I am American so I have the right to be wrong, but I never exercise that right. :D

Thankyou very much J Martin

Riverruner, I too could come back with lots of cocky comments based around nationality, but I wouldn't stoop so low.

That quote one of the members has about never arguing with an idiot comes to mind here

[riverrunner114]

Thankyou very much J Martin

Riverruner, I too could come back with lots of cocky comments based around nationality, but I wouldn't stoop so low.

That quote one of the members has about never arguing with an idiot comes to mind here


on my last post I was tring to be nice... actually didn't even realize that it was not you that had posted the one before me... but as of now I have two words that come to mind... any guesses?

[j_martin]

Lighten up!!!!

[marshan162]

Well it looks like I was posting the same time as you were posting your friendlier response.
Lets just call it a day