# Propane Mower Conversion



## tpolk

gotta love inventive ingenuity


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## homerb

The coolest part is that the blue propane bottle looks like a NOS nitrous tank. VROOOOOMMM!!! 

I get crazier looks from my neighbors when I mow my lawn than Rick Moranis gets on "Honey I Shrunk the Kid" with all his gadgets..

I was thinking of mounting a second tank on the other side and tapping it in using a T-fitting. When using one bottle, it gets cold after about 10 minutes of mowing which reduces the bottle pressure. When I'm nearing 1/4 full on a tank when it's cold, often it won't supply enough pressure to keep the engine running. I'll have to switch to another tank (often another partially full tank from the last time I mowed the lawn) or soak it in a tub of hot water. Two tanks would eliminate this problem because I could switch over, or just run both half as much. 

Homer


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## Scuba_Dave

Green mower


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## homerb

Scuba_Dave said:


> Green mower


I guess you can't get any greener than that! Zero emissions and simple. "Classic". How much do those cost?

This is a green forum, but most importantly, it's a "DIY" forum. And a propane mower is a great example of green DIY tech that actually works.


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## Scuba_Dave

They can actually be expensive, up to $200 
But a small 14" can be as low as $79, 20" @ $140--prices have come down
They sell out pretty quickly too, MIL had a hard time finding one
I would consider one once all of my gardens are in & the new driveway

My lot is 1/2 acre, but between pool area, woods, stream, house, sons play area, greenhouse & gardens there isn't a lot of grass left
I can mow the whole thing in about an hour now

And if you really want a work out on a bigger yard:


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## homerb

Scuba_Dave said:


> They can actually be expensive, up to $200
> But a small 14" can be as low as $79, 20" @ $140--prices have come down
> They sell out pretty quickly too, MIL had a hard time finding one
> I would consider one once all of my gardens are in & the new driveway
> 
> My lot is 1/2 acre, but between pool area, woods, stream, house, sons play area, greenhouse & gardens there isn't a lot of grass left
> I can mow the whole thing in about an hour now
> 
> And if you really want a work out on a bigger yard:


Haha that looks like something you'd tow behind a mule. Free lawn fertilizer too!

Here's a video of it running on the propane bottle

Viddler.com - Souped up lawn mower running on propane (1 of 2) - Uploaded by homerberkowitz

Here's a video of it running on MAPP gas!!!

Viddler.com - Souped up lawnmower running on MAPP gas (2 of 2) - Uploaded by homerberkowitz

Let me know what you think!


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## Red Squirrel

Haha that is awesome! With all that power I hope it's a mulcher at least lol.


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## homerb

Red Squirrel said:


> Haha that is awesome! With all that power I hope it's a mulcher at least lol.


It does a pretty good job mulching. I added a 21" "Gator Blade" that has mulching "tines" at the top of the blade. It's only a 20" mower, so I had to do a little "massaging" to the mower deck to get it to fit.










It does a good job chewing up pretty much everything I throw at it. The only problem with this blade is that it spits out lots of debris, dust, clippings etc. out of all sides of the mower, especially out the front. It makes a big mess of itself. I was thinking of attaching some flexible plastic around the sides. 

I was half tempted to close up the mower chute too.


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## AirCooledPropan

*Propane lawn mower bottle-icing fix*

I converted my Snapper mower to propane in Spring of '09 and used it all summer. My first conversion was just like Homerb's, except that I removed the carb and installed a home-made mixer








Like Homerb's, after about 10 minutes (give-or-take depending on ambient-temperature) the tank and torch-valve frosted up-- reducing the vaporization to the point where I had to take a break. I too had the idea to use a second tank and a T-fitting. I ending up upgrading to a new setup about a month later, which included two regulators. The first regulator takes tank pressure and reduces it to about 1/2 psi. The low-pressure vaporous propane is then fed to a secondary (demand) regulator. I purchase the demand regulator with a bunch of other propane parts on ebay with the intent to convert an antique car to run propane. For more information, please check out my website:
http://www.aircooledpropane.com/
http://www.AirCooledPropane.com/mower/rev2.htm

With the regulators installed, The mower runs until the tank is completely empty, and then dies really quick. You can buy the primary regulator at Menards for between $10 and $15; WELL-WORTH THE MONEY!!

I recently upgraded to a 5-lb tank which can be refilled for about $6.50 at my local Ace hardware. That amount of propane should last me most of the mowing season, I think. Here's a link to the upgrade:
http://www.aircooledpropane.com/mower/rev3.htm

I plan to install that 5-lb tank on a different mower, since it may interfere with the bag on the Snapper.


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## homerb

AirCooledPropan said:


> I converted my Snapper mower to propane in Spring of '09 and used it all summer. My first conversion was just like Homerb's, except that I removed the carb and installed a home-made mixer
> 
> 
> 
> 
> 
> 
> 
> 
> Like Homerb's, after about 10 minutes (give-or-take depending on ambient-temperature) the tank and torch-valve frosted up-- reducing the vaporization to the point where I had to take a break. I too had the idea to use a second tank and a T-fitting. I ending up upgrading to a new setup about a month later, which included two regulators. The first regulator takes tank pressure and reduces it to about 1/2 psi. The low-pressure vaporous propane is then fed to a secondary (demand) regulator. I purchase the demand regulator with a bunch of other propane parts on ebay with the intent to convert an antique car to run propane. For more information, please check out my website:
> http://www.aircooledpropane.com/
> http://www.AirCooledPropane.com/mower/rev2.htm
> 
> With the regulators installed, The mower runs until the tank is completely empty, and then dies really quick. You can buy the primary regulator at Menards for between $10 and $15; WELL-WORTH THE MONEY!!
> 
> I recently upgraded to a 5-lb tank which can be refilled for about $6.50 at my local Ace hardware. That amount of propane should last me most of the mowing season, I think. Here's a link to the upgrade:
> http://www.aircooledpropane.com/mower/rev3.htm
> 
> I plan to install that 5-lb tank on a different mower, since it may interfere with the bag on the Snapper.


That's cool! Thanks for the info! 

You'll need a regulator with anything bigger than a torch propane tank, correct? The reason why it runs all the way until empty is because the 5LB tank has a tube that goes to the bottom and since liquid propane comes out instead of gas, it isn't affected by the bottle pressure. 

I've seen some cool regulators designed specifically for this purpose. They are controlled by engine vacuum or spring pressure, regulating the amount of propane to keep the engine at a specific RPM based on not only vacuum, engine load, but also bottle pressure. 

If I were to convert my generator to propane, I'd need some sort of regulator like this so I wouldn't have to constantly adjust the valve to keep the engine running at a specific rpm


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## AirCooledPropan

homerb said:


> That's cool! Thanks for the info!
> 
> You'll need a regulator with anything bigger than a torch propane tank, correct? The reason why it runs all the way until empty is because the 5LB tank has a tube that goes to the bottom and since liquid propane comes out instead of gas, it isn't affected by the bottle pressure.


Thanks. I ran the first conversion off of a 1lb (coleman style) bottle for all summer last year. I use a regulator that screws right onto the bottle and takes tank pressure down to about 1/2 psi. the hose from that regulator is connected to a secondary regulator (a demand-regulator) which is a Garretson SD model. With the governor still working, the engine's load affects the throttle which alters the vacuum to the demand regulator or zero-governor, adjusting the amount of propane delivered to the mixer. A small ball valve (1/4") is used to adjust the mixture, which is mounted as close to the mixer as possible.

http://www.aircooledpropane.com/mower/rev2.htm

Sorry, but I forgot to mention this:

I am using vapor-withdrawal from the tank on both conversions. Once I began using a regulator to reduce the pressure, the tank no longer iced up, allowing it to deliver a fairly consistent vapor-pressure.


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## nap

pretty slick stuff guys. 

Now all I have to do is have a need for a mower and I could whip one up as well. 2 acres but no grass to mow. I feel left out.


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## littlehorn

I have recently worked up a set of plans for this. Mine involve a demand regulator and spud-in, so you can use them on engines with float-bowl carbs. Also, no problems with the bottle icing up, etc.

I'm just working the final kinks out of the plan set but it can be done for about $120-140 and will work just like your regular mower. The demand regulator may also slightly increase run-time per bottle as it's only pulling what it needs to run.


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## homerb

An on demand regulator is the one part I didn't use on this project. Being that I only paid $40 for the mower itself, I wanted to keep it as low budget as possible. 

I can extend the runtime on the mower by simply throttling it down a bit. The rpm and mixture auto adjust based on how much propane goes into the mower. 

I am interested in using an on demand regulator for my next project, which will need it. I have a generac 7500 w / 13,500 w peak generator that can power my whole house. I haven't converted it to propane yet because I need that on demand regulator. With the mower, I can constantly adjust the propane flow as needed, but the generator needs to be much more reliable, and it needs to auto adjust the flow based on how much stuff I have running in the house. 

I haven't even needed to use the generator once since I bought it from the pawn shop for $275, so I don't even know how much gas it uses per hour. But propane is a much better choice because it stores better, doesn't foul plugs, gum up the carb, and extends oil change intervals. Im guessing it'll run for about 4 hours on a typical 20lb tank at half load. Im hoping it'll run longer, if it is to be cost effective though. I could get one of those big 100lb tanks and have it run all day without changing a tank. 

What kind of on demand regulator are you planning to use? I've been looking on eBay lately and there are a few different kinds on there. 

Homer


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## littlehorn

homerb said:


> An on demand regulator is the one part I didn't use on this project. Being that I only paid $40 for the mower itself, I wanted to keep it as low budget as possible.
> 
> I can extend the runtime on the mower by simply throttling it down a bit. The rpm and mixture auto adjust based on how much propane goes into the mower.
> 
> I am interested in using an on demand regulator for my next project, which will need it. I have a generac 7500 w / 13,500 w peak generator that can power my whole house. I haven't converted it to propane yet because I need that on demand regulator. With the mower, I can constantly adjust the propane flow as needed, but the generator needs to be much more reliable, and it needs to auto adjust the flow based on how much stuff I have running in the house.
> 
> I haven't even needed to use the generator once since I bought it from the pawn shop for $275, so I don't even know how much gas it uses per hour. But propane is a much better choice because it stores better, doesn't foul plugs, gum up the carb, and extends oil change intervals. Im guessing it'll run for about 4 hours on a typical 20lb tank at half load. Im hoping it'll run longer, if it is to be cost effective though. I could get one of those big 100lb tanks and have it run all day without changing a tank.
> 
> What kind of on demand regulator are you planning to use? I've been looking on eBay lately and there are a few different kinds on there.
> 
> Homer


Garrettson SD is the ticket, or perhaps the KN with auto-primer. For your generator, you will want one that has an electric shut-off solenoid for positive cut-off when the engine stops. You don't want the engine to shut down and fuel to keep leaking through.

http://www.propane-generators.com/garretson.htm


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## homerb

What are the other details of your project? In addition to the regulator, what mower are you going to be using? What kind of propane tank?

Are there any other modifications you are making to the mower to make it more powerful or efficient running on propane? Bumping the compression or timing are probably the easiest and most effective modifications you can do. 

Post some pics if you can!


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## happycamperbrat

How about the noise factor? I imagine it would be quieter but Im not sure.....


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## homerb

happycamperbrat said:


> How about the noise factor? I imagine it would be quieter but Im not sure.....


It sounds about the same at normal operating RPM. However, since increased the compression ratio and advanced the ignition timing, it sounds a little different. But none of that has to do with the propane directly.

I can make it louder or quieter though...just by adjusting the RPM's with the propane valve.


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## andrew4096

homerb said:


> ... I was thinking of mounting a second tank on the other side and tapping it in using a T-fitting. When using one bottle, it gets cold after about 10 minutes of mowing which reduces the bottle pressure. When I'm nearing 1/4 full on a tank when it's cold, often it won't supply enough pressure to keep the engine running. I'll have to switch to another tank (often another partially full tank from the last time I mowed the lawn) or soak it in a tub of hot water. Two tanks would eliminate this problem because I could switch over, or just run both half as much.


Some do-it-yourselfers have solved, perhaps inadvertently, the propane cylinder chilling problem by mounting larger cylinders on their mowers. For example, see YouTube video 9F9FhK0SdRE, posted December 2013, where the fellow has mounted what appears to be a small 5-pound barbecue cylinder on the mower deck. (He may be in Australia, and the LPG equipment available there varies from what we can get in North America.) It adds weight and makes the mower a bit ungainly, but the larger mass of liquid propane, plus the larger surface area of the cylinder, help reduce the rate at which it cools as gas is being drawn off. If one would rather deal with the small, 1-pound disposable cylinders, connecting two of them with a T-fitting as you suggest and _simultaneously_ supplying gas from both would have a similar effect, as the rate of flow from each cylinder would be cut in half and the surface area would be doubled. It should make little difference whether you use the narrow 1-pound disposable cylinders for propane torches or the squat 1-pound cylinders used for camp stoves and lanterns, as their surface areas are essentially the same, within a few percent.


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## ICan'tPickAName

Something I am for sure going to try once the weather warms up. 

Tip:

If you mount the bottle upside-down, when it gets cold it will still flow.


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## bradleyshome

homerb said:


> The coolest part is that the blue propane bottle looks like a NOS nitrous tank. VROOOOOMMM!!!


Haha get some NOS stickers to add an extra 25hp :biggrin2:


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