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Old 20-05-2018, 20:42   #1
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Converting diesel to gas engine? Need help!

Hi everyone,

I work for an NGO and I am no expert on this topic. I have been tasked to figure out if it was cost efficient to convert a diesel marine engine to gas engine? We are thinking of doing a project to convert 30 boats in a fishing village (in a developing country), to help the livelihood of the villagers and improve on the pollution in the village.
The boats are around average 3.2 GT with relatively small motors (average 16 Hp).

Just want to know if this is cost efficient/ easy to convert? Do you guys have any other suggestions that we can do to help this village?

Thank you
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Old 20-05-2018, 20:54   #2
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Re: Converting diesel to gas engine? Need help!

If you can replace with outboards in wells it might be an option.
Easier to fix and swap outboards too if need be.

Still keep in mind the issues with petrol and fire risks.
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Old 20-05-2018, 21:16   #3
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Re: Converting diesel to gas engine? Need help!

Quote:
Originally Posted by Always_confused View Post
Hi everyone,

I work for an NGO and I am no expert on this topic. I have been tasked to figure out if it was cost efficient to convert a diesel marine engine to gas engine? We are thinking of doing a project to convert 30 boats in a fishing village (in a developing country), to help the livelihood of the villagers and improve on the pollution in the village.
The boats are around average 3.2 GT with relatively small motors (average 16 Hp).

Just want to know if this is cost efficient/ easy to convert? Do you guys have any other suggestions that we can do to help this village?

Thank you
Why convert a Diesel engine to gasoline engine?
(Diesel is worn out?)
There is no conversions I am aware of.
Simpler and easier to remove and replace but there are not any small Marine gasoline engines in the market. (Small diesels, yes)
Good idea with outboard motors as noted above.
Got a few more details on the above situation? Right now it makes no sense to “convert a diesel to a gasoline engine”
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Old 20-05-2018, 22:06   #4
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Re: Converting diesel to gas engine? Need help!

Always Confused, welcome aboard CF, interesting first post. As I'm not sure of your nationality / location, when you say "gas" engine, are you referring to "gasoline / petrol" as in USA speak or rather gas as in LPG gas.

There is a lot of downside using a gas / petrol engine in a boat unless it is a transom hung outboard.

We really need more info to provide a meaningful answer(s).

Open boat, decked in, shaft drive, existing engines etc...

And I'm not sure if there is a pollution advantage or not if comparing new diesel engines to other new engines.
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Old 20-05-2018, 23:37   #5
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Re: Converting diesel to gas engine? Need help!

I'd also be interested in more details, especially about the village. How do they produce electricity, do public transport, ...? And how long do they run the engines per day? And bonus question: What did the villagers say they'd need?

Concerning the marine engines: 18hp probably run at about 1-2l/h at normal speed, just a little more than an idling car. So you got the equivalent of like 30ish cars idling for a couple of hours. Even if you optimize the engines to (theoretical) zero pollution the impact is neglectable compared to any traffic jam anywhere.
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Old 20-05-2018, 23:37   #6
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Re: Converting diesel to gas engine? Need help!

It's physically impossible to convert diesel engines to gasoline. I suppose it could be done but you would need an engineer and a professional machinist to accomplish it.

Now I am no stranger to the 3rd world. I've spent half my adult life in "developing nations" (im 43) and nowhere I have been anywhere outside of the US is gasoline preferred over diesel. The fact that diesel pollution even makes your priority list makes me wonder just how much you're helping these people.

You want to saddle these impoverished people with engines that are less efficient, shorter lived, and use fuel that is dangerous to handle, dangerous to store, dangerous to transport, and difficult to obtain in austere conditions. F'n seriously? Just because you think it's cleaner than diesel????

Nowhere have I been in Africa, Asia, South America or Latin America were things running so well that we could divert funds and labor away from things like healthcare, hygiene, education, etc to fumble**** around with something like converting economical, reliable diesel engines with craptacular gasoline engines.

horrible idea. just terrible.

Make sure they even need engines. If a diesel starts and isn't puking oil, it's good. If the engines are beyond repair you have to make sure they are replaced with engines they can maintain. In Africa that means Listers (usually indian copies) kubotas, Mahindra, Tata, Mercedes These are dead nutz simple and cheap to fix. South America its kubota, yanmar, International Harvester, Mercedes. Perkins and the chinese copies of perkins and kubota are honorable mentions.

read up on the dangers of gasoline use on boats. read basic hazmat info on gas vs. diesel. If this absolutely must happen, buy them outboards and plastic tanks.
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Old 20-05-2018, 23:55   #7
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Re: Converting diesel to gas engine? Need help!

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Originally Posted by MikeBravo556 View Post
It's physically impossible to convert diesel engines to gasoline. I suppose it could be done but you would need an engineer and a professional machinist to accomplish it.

Now I am no stranger to the 3rd world. I've spent half my adult life in "developing nations" (im 43) and nowhere I have been anywhere outside of the US is gasoline preferred over diesel. The fact that diesel pollution even makes your priority list makes me wonder just how much you're helping these people.

You want to saddle these impoverished people with engines that are less efficient, shorter lived, and use fuel that is dangerous to handle, dangerous to store, dangerous to transport, and difficult to obtain in austere conditions. F'n seriously? Just because you think it's cleaner than diesel????

Nowhere have I been in Africa, Asia, South America or Latin America were things running so well that we could divert funds and labor away from things like healthcare, hygiene, education, etc to fumble**** around with something like converting economical, reliable diesel engines with craptacular gasoline engines.

horrible idea. just terrible.

Make sure they even need engines. If a diesel starts and isn't puking oil, it's good. If the engines are beyond repair you have to make sure they are replaced with engines they can maintain. In Africa that means Listers (usually indian copies) kubotas, Mahindra, Tata, Mercedes These are dead nutz simple and cheap to fix. South America its kubota, yanmar, International Harvester, Mercedes. Perkins and the chinese copies of perkins and kubota are honorable mentions.

read up on the dangers of gasoline use on boats. read basic hazmat info on gas vs. diesel.
I can't say I agree with how this is expressed, but I sure agree with the substance. Petrol/gasoline engines in boats, particularly working boats, are worse than diesel in every possible way - fuel consumption, reliability, service life (3x or 4x worse), danger of explosion. If these people are fishermen, they will have access to tax-free red diesel fuel - gasoline might cost 4x more, and might well not even be available on the fishing quays.

This is a spectacularly bad idea. Why not find a way to help them, which actually helps them?
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Old 21-05-2018, 00:16   #8
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Re: Converting diesel to gas engine? Need help!

Guess you need to clarify if you want to replace the engines or if you intend to rebuild them to run on a different type of fuel.

The latter will be very difficult to do, at least if you would want to swap diesel to benzine.
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Old 21-05-2018, 00:17   #9
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Re: Converting diesel to gas engine? Need help!

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Petrol/gasoline engines in boats, particularly working boats, are worse than diesel in every possible way
Well, with the exception of outboards. We're talking 18hp, so if replacing the engines with new ones (which probably is the cheapest way) this would technically be the way to go. Practically the fishermen would probably sell the new outboards, keep the diesels and buy stuff they actually need/want.

And about conversion: You'd need to lower compression which means new crankshaft and / or pistons, connection rods, ... And the complete fuel mixture stuff like injectors, pump, ... And maybe a new head (in case of a precombustion chamber). So yeah, doable as a interesting exercise for a gearhead but not feasible in any real world application.
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Old 21-05-2018, 01:15   #10
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Re: Converting diesel to gas engine? Need help!

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Well, with the exception of outboards.
Yes, granted.

But a good professional-grade outboard (Yammie Enduro) still has a much shorter useful life than an inboard diesel, and still uses a lot more of a more expensive fuel. No third world fisherman who has managed to attain an inboard diesel is going to want to go back to outboards.


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Originally Posted by _andi_ View Post
We're talking 18hp, so if replacing the engines with new ones (which probably is the cheapest way) this would technically be the way to go. Practically the fishermen would probably sell the new outboards, keep the diesels and buy stuff they actually need/want.
Indeed!
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Old 21-05-2018, 01:44   #11
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Re: Converting diesel to gas engine? Need help!

Many diesels have been converted to run on methane. Usually in operations that make methane out of excess animal waste. Some converted engines runs with the addition of a spark plug and some control of the gas.

Fairbanks-Morse makes diesels that are dual fuel. Used in power generation. They start on diesel and switch to natural gas.
Running a diesel on gasoline has several problems. The compression ratio is higher in diesels so the fuel would tend to pre ignition. Also you need a carburetor matched to the air flow and somehow fit spark plugs into a head design that didn't allow for them. And then you need an ignition system, distributor and a way to time it to the engine.
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Old 21-05-2018, 02:34   #12
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Re: Converting diesel to gas engine? Need help!

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Originally Posted by Always_confused View Post
Hi everyone,

I work for an NGO and I am no expert on this topic. I have been tasked to figure out if it was cost efficient to convert a diesel marine engine to gas engine? We are thinking of doing a project to convert 30 boats in a fishing village (in a developing country), to help the livelihood of the villagers and improve on the pollution in the village.
The boats are around average 3.2 GT with relatively small motors (average 16 Hp).

Just want to know if this is cost efficient/ easy to convert? Do you guys have any other suggestions that we can do to help this village?

Thank you
How about a Go Fund Me page? It will NOT be cost effective to try to convert diesel engines to gasoline; it would be cheaper to buy used outboard motors.
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Old 21-05-2018, 02:37   #13
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Re: Converting diesel to gas engine? Need help!

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Originally Posted by Lepke View Post
Many diesels have been converted to run on methane. Usually in operations that make methane out of excess animal waste. Some converted engines runs with the addition of a spark plug and some control of the gas.

Fairbanks-Morse makes diesels that are dual fuel. Used in power generation. They start on diesel and switch to natural gas.
Running a diesel on gasoline has several problems. The compression ratio is higher in diesels so the fuel would tend to pre ignition. Also you need a carburetor matched to the air flow and somehow fit spark plugs into a head design that didn't allow for them. And then you need an ignition system, distributor and a way to time it to the engine.
I carried out research on the Fairbanks-Morse dual fuel system years ago in relation to a town generating system which was near a natural gas well.

As I recall the details there were no modifications required to the engine other than the fitting of a demand regulator to the intake system. The normal injector system was used to initiate engine startup and then a stream of gas was introduced into the intake manifold to mix with the air the engine was breathing. As the revs increased the speed governor cut back on the diesel being injected as the gas/air mixture provided the required fuel load. When the diesel proportion had reduced to 10 to 15% it ceased to reduce thereby maintaining compression ignition for the gas/air mixture.

If the gas was shut off or reduced for any reason the governor increased the diesel being injected to maintain the engine revs.

This would be an excellent system for remote villages which wished to replace some proportion of their imported fuel costs with locally generated methane gas using bio-waste generators.

If one had sufficient methane (the primary constituent of natural gas) it might be economic to install compression facilities in order to implement a CNG system for transportation systems. There are thousands of buses running on CNG in Europe.
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Old 21-05-2018, 02:40   #14
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Re: Converting diesel to gas engine? Need help!

Greetings and welcome aboard the CF, Always.
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Old 21-05-2018, 03:00   #15
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Re: Converting diesel to gas engine? Need help!

it might be more productive to investigate adding sails to the vessels!
up untill 200 years ago almost 100% of fishing vessels were sail powered.
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