Engine Hacks: Convert Your Yard Tools To Run On Steam!

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Are you tired of doing things the efficient way when using your lawn equipment? Look no farther. Here are some engine hacks where regular internal combustion engines have been modified to work on steam or compressed air. Surprisingly, all it takes to do this is to remove the carburetor and replace it with a steam line and to modify the valve timing.

First up is a lawn mower that runs on steam posted by [dquad]. This one is pretty great because it just looks so wrong. In [dquad’s] own words: “I am surprised by the fact that nothing at all failed during this test – other than a wheel catching fire!”


Check out some other examples of engines converted to run on air or steam after the break…

Here is video posted by [greenpowerscience] where a two-stroke engine has been converted to run on air and which also has a solenoid valve to control the air.

Finally, if you are wondering how these folks are converting their engines, take a look the second video on this page where the valve modifications are shown.

45 thoughts on “Engine Hacks: Convert Your Yard Tools To Run On Steam!

  1. I love building steam, and have no problems with dangerous stuff, but PLEASE don’t play with this stuff unless you really know what the hell you are doing. People have no idea how much destructive force steam has, and that thing can and probably will kill someone. Not a toy. Steam is really deadly.

    Beyond that, an engine is just an air pump anyway. Steam, compressed air, or expanding exhaust gases are all the same thing to the engine. Whether its internal or external combustion doesn’t matter, you have expanding gases ether way.

  2. I love it. At first site, it makes somebody think you are starting a fire underneath a tank filled with propane rather than water. I would like to have this thing just to make my neighbors go into a frenzy!!

  3. Well, It’s a start.
    A good tip…..
    First off, use some fire proof wheels, a self contained fire box,that also supplies stoking pressure to keep the fire hot, because the battery and fan are gonna become an issue.
    The firebox should also have some firebrick or some other media like lava rock like in grills etc.
    The latter would be more weight efficient.

    ^^ this is not fuel efficient but if your aim is to get your “Steampunk” on then there ya go a good tip to make some safe changes.

    PS a safety valve is always a good idea.

    1. Inre: Solenoid life, automotive Fuel Injectors are solenoids built for long repetitive lives, perhaps one of those could be hacked to work. But FI ‘noids are “cooled” by the fuel they inject, the compressed air would have to do that. Expanding compressed air absorbs heat (Boyles? Beers? law)
      so maybe a bit of air leakage could be incorporated to cool the ‘noid.

    2. I imagine that crank would last about 2 minutes under any kind of a load, but cool experiment anyways… and I have some spare Fuel Injectors sitting around… I have a couple 19 and 22 lb/hr injectors (take 45 psi input pressure) and some 61 lb/hr injectors (takes 9 to 13 psi input pressure)from chevrolet applications. I’ll stick one on the compressor to see how it holds up, and what kind of duration i have to open the Noid to get a decent volume.

    3. No evidence that they did so, but since the crankcase is no longer a part of the fuel circuit, you could put actual oil in there.

      Still need do do something to lubricate the top end. If using actual steam, you could use a displacement lubricator to carry some oil in. (on air, an air tool inline oiler would have the same function). For those that don’t know what a displacement lubricator, see http://the-nerds.org/Steam-101.html

      The nice thing about electronic valving is that you can easily do adjustable cutoff, with a suitable controller.

    1. Well in theory when the whole thing bursts into flames, the heat from the fire will cause the extinguisher to explode. There by putting out said fire with only a minimum of shrapnel.

      Yay Science!

  4. Just running a steam line to the intake manifold won’t work if you are running anywhere near enough steam pressure to do real work. Biggest problem is that the valves will lift off their seats usually starting around 50 psi.

    If you have an overhead cam engine with appropriately spaced intake ports, with some head sized metal plates, you could run the head on its “side”, with the steam fed to the combustion chamber of the head, the valve popping open, and letting steam thru to the cylinder. Add two stroke style exhaust ports (into what was the water jacket) to let the steam out. You would need to either re-grind the cam, or run it at 1:1 so you don’t have a dead stroke.

    Getting oil to the valve train, and more importantly keeping the steam away from the rest of the lubrication system is an exercise for the reader. (steam combined with ordinary motor oil results in something resembling beige mayonnaise)

    Since this is hack a day check out http://the-nerds.org/Steam-Car-Day.html for the steam conversion I had a hand in.

  5. My new heros :) All jokes aside, something like this would be very useful in 3rd world countries where liquid fuel is too expensive. Just put some wood on the fire and you are good to go.

    Heat engines are more efficient in larger sizes though (less heat loss, etc).

      1. I agree that high pressure steam is extremely dangerous. But Stirlings have their own problems: very tight manufacturing tolerances due to fairly small pressure differentials make them more expensive to make.

        A solution might lie further in the past: an atmospheric Newcomen/Watt steam engine. There is no high pressure there – piston is moved by atmospheric pressure when vacuum is created underneath it. Look at http://en.wikipedia.org/wiki/Atmospheric_engine for details.

    1. As much as I love steam power, those same third-world folks would probably be better served with a “gassifier” (more properly a pyrolyzer) which can produce fuel for an unmodified 4-stroke IC engine out of said wood.

  6. hahah! Imagine the cardiac arrests you can cause when people see an LP tank sitting on a raging fire!

    Actually, that’s an interesting way to make a boiler, since the LP tank is already rated for some pressure, but it just looks crazy. Maybe if you painted it black or grey or something, it might not trigger the duck-and-cover reflex quite so much.

    1. The LP tank doesn’t have a whole lot of surface area to take up heat. If you look at a “classic” locomotive boiler, you will find a bunch of tubes through the water holding part of the boiler. The heat of the fire passes through the tubes, so there is more opportunity for heat transfer.

      The hard part of a steam conversion is not the engine, its the boiler. For something without moving parts, they are pretty complicated to design. The need for a lot of strength at elevated temperatures, and the amount of energy they can release if they break, means you have to get all your sums right.

      You also need some extra systems, you have to be able to add water to a boiler while its under pressure. For vehicles, its helpful to be able to control the size of the fire, so its size matches the medium term need for steam generation.

      1. Well, I said it was interesting; I didn’t say it was a particularly good idea. I certainly would not try it myself. The tanks normally hold back whatever the vapor pressure of propane at ambient is, so you certainly wouldn’t want to exceed that pressure. But then, under normal circumstances the metal isn’t being subjected to a 1000 degree F bed of coals, so you’d have to derate for for that. It might not be filled with what it looks like it would be filled with, but it could still go ‘boom’, that’s for sure.

        1. That burning bed of coals can easily have real 1000 degrees (1000°C) not only °F.
          Re steam explosion: At first it would be one also with the propane. Of course an expanding cloud of hot propane vapor over a fire is something best watched from great distance.

  7. This prompted me to do a little research, and I came across this bad boy.

    I also came across this quote, which made me treat the whole idea of using steam with a lot more respect:

    Why worry about the amount of heated & pressurized water? picture a very small boiler, maybe the size of a fifty five gallon drum. Rough dimensions of one of these drums is around 24 inches diameter & 36 inches long; about 9½ cubic feet of water at 70 pouds per square inch *gage* and at 316°F.
    What happens if the boiler springs a leak? Pressure immediatley falls. Since there is less pressure on the heated water it imediatly starts to boil. As the water boils it produces steam which raises the pressure on the water that inhibets boiling. This condition normally exists in a boiler & produces a controlled reaction. The “Leak” is the boiler steam outlet pipe.

    But what happens if there is an uncontrolled leak in the boiler such as equipment failure might produce? As pressure drops & water starts to boil there is no restriction to stabalize the pressure and ALL the water can imediatly flash into steam. In our example if you started out with 9½ cubic feet of superheated water & reduced the pressure to zero you almost instantaneously have 1200 times this volume of steam, equal in volume to a single storey house 35 by 40 feet. You suddenly have 11,400 cubic feet of steam in a 9½ cubic foot pot & a real- but short lived- problem; a massive boiler explosion.

    At the core of the explosion is super-heated steam at 316°F. If the shrapnel & concussion is daunting enough, this 316°F steam will instantly cook any flesh it comes in contact with & can literally strip flesh from bones. Does the avrage small homesteader want to play dice with this process?

  8. I love projects like this; they make my insanely wasteful ideas look practical.

    He needs to get together with that mad scientist guy that was making a reactor in his kitchen…after all, what good is a reactor unless it is boiling water or melting down? Fear not…it would do both on a riding mower!

  9. Nothing like a steam powered lawn tractor on a hot summers day. Just looked at some videos of his steam powered lawn tractor. Kind of curious how well the turbo is going to work for supplying forced air into the fire box. If it works he is going to hit OMG levels of heat in his firebox. My one suggestion. For the love of Life install a pressure relief valve. I do not want to here a news report of “guy killed in steam explosion mowing lawn” video at 11:00. Very important pressure relief valve.

  10. As someone that has been involved in converting a 4-stroke motor to run on compressed air(which is pretty much the same mechanic conversions as you would need for steam) i can say this is unbelievably simple to do.

    Have a lookie if you want… i dont have a writeup of what we did or anything, but if memory serves, all we really needed to do was add a second lobe to the cam using copious amounts of arc welding :)


  11. Something tells me that you either weren’t using a lot of pressure, or your valve seals were bad enough, that when the valve was closed, it escaped around the seal, rather than lifting the valve off its seat. (or given that it was a bike engine built for high revs, had stiff enough springs for the small size of valve that you caught a break)

    Every “serious” attempt to run a conventional engine off of external pressure, runs into the problem that poppet valves resist pressure against the face very well, and against their back, poorly.

  12. @rjnerd I had the same thought… the valves are going to pop open as soon as the spring pressure is exceeded.

    It doesn’t seem like combustion engines are good candidates for steam or air power conversion.

  13. As for the steam mod, using a propane tank is not what I would call safe. Propane tanks are typically pressurized to 100psi at around 70 degrees F. It would not take much for steam to double that pressure and blow the tank. I hope he has an overpressure vent on that contraption or he is risking some serious injury.

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