Converting a generator to run on propane

A step by step instruction on how I converted my generator to run on propane as a back up fuel source. There a numerous reasons one might want to do this. You might need a cleaner burning engine. You might not want to store or carry large amounts of liquid fuel around, besides liquid fuel eventually goes bad, propane will not. Its easier to store large amounts of propane. In an emergency situation such as hurricanes and earthquakes, gasoline might not be available or if it is, it will be in high demand, propane usually is not.

I found several ways of doing it on the web but nothing that seemed permanent or cheap. They have kits to do this but I didn't feel like forking out 100+ bucks to do it. This project cost me about 25 bucks and thats because I wanted new parts. If you had the parts laying around you could get out of it cheaper.

Step 1: Warnings

WARNING This could be dangerous if the motor dies and your not around, the propane will continue to run and could possibly build up and you would have a nice explosion. The kits available commercially have a safety shut off or an on demand regulator that will shut the gas off when the engine dies or is not running so they will not flood the area with propane.

I run my generator outside on the driveway and know when it dies so I don't have a problem with the way I did this. Besides, with the wind blowing, I would never have a problem with gas build up. NEVER run the generator indoors with propane or any other type of fuel for that matter. Propane is heavier than air so it will collect on the floor or near the ground when it is allowed to escape out of the tank. Use this instructable at your own risk!!

Comments

[simonkoenig911]

i was just wondering about that safety shutoff valve... if you had an engine with an alternator on it, could you use that to power a solenoid valve, so the minute the engine stops turning, the propane supply would turn off, and you could have a manual override button for starting. anyone got any ideas on this?

[The 4th Doctor]

sounds like a great idea to me, on any generator you could just run it off of the wall voltage output too. i cant find any cheap solenoid valves though.

[pcooper2]

The 4th Doctor, during a power outage there is no "wall voltage". The system needs to be self-contained for safety.

[Rainh2o]

I think he means run it off the wall voltage output on the generator.

[simonkoenig911]

quick search on amazon brings up a few for about $15. will you be converting a generator?

[dunklesubel]

You should NOT use teflon tape on compression fittings, especially if you are running flammable liquid / gas through the lines.

[pcooper2]

Why would heavy duty Teflon tape be sold in most hardware stores, specifically for use on natural gas lines? It is usually yellow in color and much thicker than the white tape used for water lines, but Teflon nonetheless. Teflon is essentially inert in the presence of all hydrocarbons used as engine fuels or heating fuels.

The only issue I would have is use of any kind of tape, putty or sealer on compression fittings. Compression fittings are supposed to be liquid- or gas-tight on their own; if they aren't, they need to be fixed or replaced.

[Rainh2o]

I agree pcooper2.

[Rainh2o]

Why not?

[neardood]

Wouldn't manually controlling the RPM of the generator cause it to make too many or too little volts? Not good for running any kind of sensitive equipment. In the video you can see the governor trying to adjust the revs to regulate the output

[Rainh2o]

What sensitive equipment do you plan to run when the electricity is down for so long that there is no gasoline available and you need this to draw water with the water well, heat your house a bit and maybe charge some batteries and run some lights? Lights dont care, as long as the voltage and rpm are close, the motor on the pump wont care for short term and batteries dont care either.

[pcooper2]

Depending on the generator design, it can be made to produce relatively constant output voltage with varying speed. The issue is that this is an AC generator, and uncontrolled variations in engine speed will produce variations in AC frequency. In North America we use 60 Hz power, although most appliances will probably work fine over a ±10% range (~ 55 Hz to 65 Hz), with reduced efficiency at either end. Don't expect to run something with a built-in clock that depends on line frequency for accuracy, though.

An AC generator should have a fully functioning governor to maintain proper output frequency.  This project describes an "open loop" system, i.e., no feedback whatsoever for maintaining engine speed under varying load and environmental changes.  For all the work involved in this Instructable, it is no better than sticking a propane hose into an unmodified carburetor inlet.

[Rainh2o]

Yep..unregulated...but in a power outage when gasoline is not available this WILL work to charge batteries, run water pump, give you lights, let you take a shower, flush toilets (Im on a water well so we need electricity to run pump to get water) run a washing machine, maybe even warm up the house. Its better than nothing even unregulated. Actually sticking a 14 psi hose into the mouth of the carburetor would be easier, I just wanted to see what I could do with the old carb and give people an idea what was possible.

[Wesley666]

Don't generators have a regulatory circuit that componsates for that? I have a diesel generator and as long as its running within about 1000 rpm of where it should it has 125v no problem, so low voltage shouldn't be an issue, maybe lack of amerage. The reason that generators need to run at a specific speed though is because of the Hertz I believe. They usually run at 3600rpm, which means 60 turns a second which would equate to 125v at 60hz. Rpms would affect the hz, but I don't think it would affect the power output to majorly.

The real problem I see is that all that has been worked on was the carb. Propane burns much dryer, and I have heard that propane engines need a modified lube system because they need more lube, otherwise they will wear out fast or even seize. Someone said once that they had a diesel tank on their propane power pickup because it injected a bit of diesel with the propane because the diesel helped lubricate or something. Said it used a very small amount of diesel and he only had to fill the diesel tank maybe once a year. That is just what I HEARD, it might be something to look into, it might be nothing at all.

[Rainh2o]

Im not sure why it would need a different lube system ina gasoline engine. Oil is not inside the combustion chamber when it fires with gas or propane. It is is you would burn through your oil. Thats what the rings are for, to scrape the oil off the walls. I dunno, thats the way I understand engines anyhow. Diesel, maybe, your talking way more compression and heat there and I can see the diesel acting like a lube because it is injected directly into the cylds. But a gas motor should not have oil in the cylds, you get smoke and fouled plugs otherwise.

[Wesley666]

Yes, your knowledge of engines is correct, that does not mean that everything burns the same way. Propane burns very dry compared to other fuels, and will cause significantly more wear on an engine. Some of our engines at work are propane powered but have no added lube system or use any other fuel mix and once a month we have to change the piston and cylinder walls. Usually when we change them, the top of the cylinder is pitted beyond belief, and the rings are either completely eaten away or seized to the piston, or welded, that would be a better word. The cylinder sleeves are usually heavily scarred as well. They are gasoline engines that have been converted to propane because it was problematic trying to get gasoline trucked in to sites, and they never had problems like that when they were run on gas, it was only after we changed them to propane did they require maintenance. Immediately after changed them to propane, they started failing catastrophically after about 3 months of use, one after another after another, usually pistons became so pitted they shattered while they ran and we figured out in a hurry that they needed maintenance sooner and needed it constantly.

So its not so much that the oil isn't doing it job, it is, but its in the bottom end, and the propane just wreaks havoc to the top end.

That is my experience with propane and engines that run on it. Apparently there is an injection system we could add to the engines so that they don't need so much attention, but the people at the top rather pay some guy an a55-load of money to implement his new safety system that really doesn't work! Haha!

[Rainh2o]

Everything I have looked up on running engines on propane since this part of the thread started insists you get longer engine life, due to no carbon build up and the fact that there is way less particulates in the propane so it burns real clean. I know fork lifts burn propane, does anyone have any experience in forklift maintenance and if so, are they just normal engines that have a converter for a carb?

[Wesley666]

Aren't forklifts usually electric or compressed air? And that is just what I have dealt with with propane engines. Usually yellows the piston and walls on ours as well.

[rimar2000]

Your work is far better than mine, Rainh2o.

How many hours lasts that propane container running? I tried to use natural gas, but I can't apply charge to generator.

[londobali]

Great 'ible, Rainh2o!
Thanks for sharing..

As for safety shut off, Rimar2000 did a pretty neat trick with his conversion, and was cheap too..
he used a solenoid valve that was for a washing machine (i think??), just need to be sure it's a normally-closed type.
Oh wait, i thing he ended up with having to modify the solenoid to allow a higher flow, or something..

Did you compare which one runs cheaper: the propane or the gasoline?

Anyway, thanks for sharing.. If i knew it was this easy (and cheap) I would have done it when i lived in Borneo where they have power blackouts every day for three hours!!
Cheers!

[Rainh2o]

This is what I have found so far about running engines on propane:

-Power output is slightly reduced, so there is less stress.

-Effective octane is very high, so the engine never suffers from detonation related stress.

-There is no liquid gasoline to wash the lubricating oil from the cylinder walls, so ring and cylinder wear is minimal.

-Combustion is usually very complete, so there is little carbon left in the cylinder, which is lightly abrasive.

-The complete combustion means that there is very little acid etc in the blowby, so the oil tends not to break down or otherwise get nasty.

[dereal]

Hey!!! Great Job! But which site can I get the pdf manual or guide using the gas conversion kit?---Some should forward it to my mail:[e-mail]

[dereal]

Hey!!! Great Job! But which site can I get/read the pdf manual or guide using the gas conversion kit?

[trike road poet]

To end the backfire/explosion worries, just go to a local welding shop and buy a flame arrestor, a simple device used on cutting torches to prevent flame burning back up a torch hose and into the tank. The one for the Acetylene tank would likely work well, and the guys at the welding shop can aid you with selecting the right fittings to make the arrestor fit into your rig.

[mpikas]

I don't get it, why go to all this effort?  You could just drill and tap a hole someplace in the casting and leave the carb functional, maybe put a shutoff valve in he gas line. 

That way you have a setup that can be used for either, shut off the gas and run it on propane, or close the propane valve an run it on gas...

[Rainh2o]

first I didn't want to drill a hole in my airbreather.  Second I had the old carb laying  around and it was trash and just  wanted to see what it would take to make it work like this.  No other reason.

[mpikas]

Yea, i get that you had the junk carb, but my point is that you didn't need to even mess with that.

A MUCH better way of doing this is to find an open spot in the carburetor casting, intake casting, or maybe make a spacer 3/8-1/2" thick using the carb gasket as a pattern (could be out of anything, aluminum would be best, but lots of plastics will work, as will any decent wood (soak it in "aircraft dope" or model airplane stuff from SIG, thin epoxy or a dozen other things to seal it), then drill a hole in the side of it and tap it for an 1/8" NPT thread.  Then take a brass hose nipple with a 1/8" NPT thread, solder, epoxy (JB weld...) or braze a short length of tube into the opening on the threaded end, and then crush the end so it acts to spray the propane into the throttle bore when threaded into the hole in the spacer.  The crushed end will give it some velocity and turbulence so it mixes better and you shouldn't have to worry as much about throttling the airflow in, it should run well over a broader range of mixtures.

Hook up your regulator + needle valve to the hose barb with a length of hose making it convenient and go for it.

[menahunie]

I agree.
My generator I drilled and tapped a hole in the intake manifold; similar to the one you see in the video.Took the carb off first to make sure I got the chips out.
I used a piece of propane hose clamped to the fitting screwed into the intake manifold with a male quick connector ( i stick a rubber cap on it when not hooked up ) to hookup the generator to the propane regulator. I also use a electric cut off valve that uses 12v; ( I use the 12v port on the generator - stops no 12v ) - no 12v it closes and turns off the propane. I use an adjustable regulator at the propane tank.
If I am using the generator camping or work I run it on gas or propane depends where I am. My truck runs on propane so I have around 45 gallons when truck is full. I just screw the fitting onto the fill port of my truck using high pressure propane hose to a regulator and hook up to the generator..

[Rainh2o]

Your right that would work.  Might be easier for some who knows.  I just WANTED to use the old carb to do it.  No real other reason then seeing if I could make it work.  Kept the carb out of the land fill and kept me entertained for a weekend.  In most simplest method you could just drill a hole  in the top of the air breather casing and stick the regulated flow of the propane into that and make it run.

[menahunie]

you could have left the butterfly in to control air flow...

[derhul]

Good idea!!! I never knew you could do this to portable gas generators

[markger14]

where did you get your propane? is it from lpg tank?

[Rainh2o]

Yes a BBQ grill type tank

[Phantasmagoric]

Wow, pretty cool. I'm trying to find stuff on converting small engines to run on alternative fuels to do a project for school... Would this be safe/easy enough to do on a lawn mower engine?

[Rainh2o]

Thats basically what my generator engine is, a lawn mower engine.

[kubbetta]

It is very good project.I managed to convert a 2 stroke generator,but the problem is how to lubricate the piston, as before it worked on mixed petrol and oil.Any ideas

[kaado505]

well you could put the propane in the air intake and where the gas used to flow you could put the oil and turn the throttle low so it only lets a little oil in then control the speed by a regulator for the propane

[Rainh2o]

you would have to devise a way to inject or drip oil into the air stream after the propane enters the carb

[compaq1501]

 i know its been a while since anyone commented on this instructable, but i wanted to convert a weed whacker/eater to run on propane from one of the small camping stove sized propane tanks. What i was wondering is, is it possible for the motor to back fire and ignite the propane? This is for an experiment so it wont actually be cutting weeds, at least not yet, and i dont want to blow up one of the tanks. Did anybody use some kind of bubbler or flash back arrester or anything?

Thanks in advance to whoever can help 

[Rainh2o]

Sorry to take so long to respond to this.  I wouldnt use a weed whacker engine for this. You have to mix oil and gas in a 2 cycle engine and by running it on propane through the carb, you would be removing the oil, and it wont run very long at all, maybe 15 mins before it locked up.