Converting diesel to gas engine? Need help!

[denverd0n]

Lots of good information here, but without more details from the OP we are just talking in circles.

Is he talking about converting the existing diesel engines to use a different fuel -- either gasoline or natural gas? Or is he talking about replacing the existing diesel engines with something else? Only he knows for sure.

Of course, converting an existing diesel engine to run on gasoline is a no-go. I think we all know that. Converting an existing diesel engine to run on LP or natural gas is more feasible, but still not easy. Replacing the existing diesel engines with something else -- preferably an outboard -- might not be a bad way to go. Though, as observed, the villagers are probably smart enough to realize that they can sell the outboards for more than they'll make in a year or two of fishing.

In any case, more info is required from the OP before this discussion can go anywhere that will be useful to the OP.

[Mariano]

I´m no expert, but heard a couple of times that the diesel to gas (propane/methane or other) convertion is only good in big, low and stable RPM diesels as generators and large trucks, and that with a small diesel the problem is controlling the RPM's from going over de red line, even with the latest electronic control units (As I said I'm no expert, just what a guy that installs natural gas convertion kits in cars told me)
You can find a lot of gasoline cars an trucks runnig on natural gas in Argetina and Brasil , but very few diesels, and always 18 wheelers.
Fair winds

Mariano

[_andi_]

Originally Posted by RaymondR

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.

Interesting concept, found some infos. But probably not for a small boat. Smallest available unit has 40 tons of dry weight.

FM-MAN 32/40 Dual-Fuel Engine Generator Set | Fairbanks Morse Engine

Enviro-Design Dual-Fuel Engine | Fairbanks Morse Engine

[lvictorlucas]

Simple:
1) Add gas tank in a safe way.
2) Add carburetor.
3) Calculate compression ratio based on gas octane available,
4) Increase head volume at TDC to lower compression (custom head spacer).
5) Drill and tap head for spark plug.
6) Add high voltage coil(s).
7) Add distributor or some timing mechanism (gear off crank or pickup from crank pulley).
8) Modify timing curve.
9) Repitch prop.
10) Give up and buy an old Atomic Four, install it and repich prop.

[boat driver]

I do not agree with the negative comments on a fairly innocent research project, PARTICULARLY FROM SOME OBVIOUSLY LIMITED KNOWLEDGE.

Yamaha and other engine manufactures have ongoing research in just this subject- improving the third world productivity via efficiency of propulsion and vessel design. The two are hand in hand.

The concept of changing existing diesel engine blocks to Natural gas is today's head scratching.(Big ships are crunching the numbers of gas, scrubbers, or ultra low sulfer oil (which is in very short and limited location supply)) The technical's of doing it are not new- transport pipelines often change/upgrade pumping stations to run on product or local supplies, the issue is generally fuel supply logistics and vessel design parameters.

My suggestion is to first call a commercial pipeline company and understand the technical concept. Second, look at multiple type fuel(s) availability infrastructure for the location you are pursuing. Then pursue the economics of the change.

Third world, first world, any time- fishing /maritime is a business. decisions made will be financial and risk based. simple.

Interesting discussion.

[Compactorguy]

Leave them alone or supply them with spare parts for their existing motors

[HopCar]

This is such an obviously bad idea I suspect the OP is a troll just trying to stir us up.

[Minggat]

Note that the OP has not chimed back in. Save yer keystrokes.

[Dave22q]

IMHO gas engines pollute more than diesel. That said, conversion is a bad idea. Far faster and cheaper to give them outboards.

[rbrentp]

My company runs diesel motors, mat gas, and HFO.
The biggest difficulty in the conversion to NG is the variability of the components in the gas. We find the supply changes a lot from one part of the US to another. Oversees it is worse.
In a nutshell, if the gas is heavy in methane it takes a lot more to get HP than a supply heavy in propane.

To an earlier point, our smallest LPG generates 50 KW

[mindsofman]

Please, tell me you are joking.
Or explain to me the extremely dire
Circumstances this village is in to even
Consider this conversion..
OUTBOARDS...

[Cadence]

Originally Posted by HopCar

This is such an obviously bad idea I suspect the OP is a troll just trying to stir us up.

Lets see if the OP responds with something not as vague.

[fatherchronica]

I think compression would be the thing that made it near impossible or at least more expensive than replacing the engine. That said, I once lived in a very remote jungle surrounded fishing town. No utilities whatsoever, or even phone service. At least once a month a house exploded burning its occupants to death because they stored gasoline usually under the front porch.

[hamburking]

To answer your question...NO you cannot convert a diesel engine to run on gasoline.

A diesel engine has a high compression ratio around 20 to 1. A gasoline (or petrol if you like) has a compression ratio of around 8 to 1. This is a fundamental of the design. You would have to decrease the stroke of the pistons by more than half. Its just a totally different system.

In addition, gas engines need a spark plug and electrical spark, which are totally absent on a diesel.

And finally, diesels are usually the preferred engine for marine use... simpler, better fuel economy, long lasting. Most people want to remove gas engines (like the atomic 4) and replace with diesel (like a nice yanmar or beta marine).

Was the OP just click bait? Seems like it to me.

[lordgeoff]

Originally Posted by Always_confused

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

I’ll be a bit more blunt than the polite gents and ladies on this forum.
Firstly why are you “tasked to convert diesel to gas” when an NGO would have access to professional advice.
I’m sure running more efficient and less polluting engines in their fishing boats would be at the bottom of the villagers needs.
Take their Diesel engines off them and you will have a riot.
Might be at the top of the NGOs needs but that would be another story.
Perhaps focus on Health Education Food.....?,