Hackaday Prize Entry: Open Source Diesel

There are plans for open hardware farming equipment that can be brought to third world countries to relieve the beasts of burden and increase the production of fields. Want an open source car? You can 3D print one. Just about anything you can strap a motor to has been replicated in open hardware; all you need to do is buy a motor and bolt it on.

But what about the motors themselves? For his entry to The Hackaday Prize, [Shane] is designing an open source engine. It’s small, it’s a two-stroke, and it’s diesel, but it’s completely open hardware; a great enabling project for all the open source dirt bikes and microcombines.

The design of [Shane]’s engine is based on the Junkers Jumo 205; a weird engine that had opposing pistons in one cylinder. This allows the engine to have variable compression, allowing for a wide variety of fuels to be used. If you have kerosene, that’ll work with this engine. French fry oil will as well. It’s exactly what you need for an engine that could be used for anything.

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72 thoughts on “Hackaday Prize Entry: Open Source Diesel

          1. Actually, the term “French fries” is short for “French fried potatoes”. French frying is a culinary term that was common in the early 20th century, used to mean the same thing as deep-frying. One of the earliest known references to fries in this manner dates back to 1802, when Thomas Jefferson was said to have eaten “potatoes served in the French manner” at a White House dinner. The term “French Fried Potatoes” first occurs in print in an 1856 cookbook, titled “Cookery for Maids of All Work”.

  1. You cant change the compression ratio, not without somehow moving one crank in or changing the length of the connecting rod. This would be an incredibly complex engine to build and there is just no need for it.

    There are many designs out there for very simple diesels like the Listers and their “Listeroid” derivatives which are used all around the world. These things will run off just about anything you can dump down them from low grade diesel to seed oils like rapeseed oil. I saw one running locally that was powering the mill that was extracting the oil it was running on.

    They run forever too, I have heard stories of these engine out in the middle of nowhere running for 20+ years without being shut down and the oil being changed while they are running.

    1. You can change the compression ratio by adjusting the phase between the crankshafts. It move the syncronizing gear over a tooth. We still use this style engine for generators on navy ships. Check out a Fairbanks 38-8 1/8th

    2. You can’t change the geometric (static) compression ratio without altering the physical size of the chamber that is correct. But, you can change the effective compression ratio by increasing the pressure in the chamber. For example, if you have a geometric (static) compression ratio of 40:1 and you are at an altitude of 1,000 feet by increasing the cylinder pressure by 15 psi your effective compression ratio becomes 80.62:1.

      Theory: An ECU (engine control unit) attached to a knock sensor and controlling an electric turbocharger could sense an engine ping when different fuel is introduced and increase/decrease the effective compression ratio allowing the engine to run smooth.

      Please keep in mind I am using the “think outside the box” method on this project so some concepts might seem unorthodox. I welcome and comments, suggestions, critiques and ideas anyone is interested in throwing out.

      1. The geometry inside the cylinder changes by altering the phase between the two pistons.

        If they’re in phase, the space between the cylinder heads remains constant and there is no compression. If they’re out of phase, there’s maximum compression because the piston heads slam against each other.

      2. You’ll find electric turbocharging a) is by its nature not turbocharging (turbocharging being a shorthand to turbine driven supercharger, if its electric driven, its not turbine driven) and b) has been proven non viable with current technology. The energy required to generate a meaningful boost pressure is just too damn high. For a 2 litre engine (of course yours is alot smaller), to generate 15psi at 5000rpm ultimately requires 12.5kW once the compressor inefficiency is accounted for, or over 1000A at 12v. Of course you may be running much lower displacement and possibly rpm, but you are still going to need vast amounts of power relative to the size of the engine. Maths here: http://forums.mightycarmods.com/showthread.php?12362-Ebay-Electric-Superchargers-The-truth although oriented around the cheap ebay units sold for automotive use.
        You are best off with plain mechanical supercharging, if further boost is required then add a compound turbocharger.

        Also notable that 2 cycle and valveless are not mutually exclusive. There are valveless 4 cycles (wankel) and valved 2 strokes (old detroit diesels)

        1. This is why such systems do not rely upon 12V systems. Electric cars are 300V+ which would bring that amperage down to 40 amps. Electric supercharging is viable, but the motors running then are 48-180V or more motors to keep current down. As for charging, super caps or a form of lithium chemistry cells are utilized.

          1. Nothing stopping you from using a waste gate or VNT setup to vary the compression, even if you wish to maintain a static RPM.
            Heavily bias the compressor side. Look at the dual compressor stuff from Garrett.

      3. Oh, it should also be noted that on these valveless 2 cycle designs, achieving usable boost pressures is very difficult. With inlet and exhaust ports open simultaneously, most of the additional airmass is forced through the exhaust port, ultimately you are left with no boost. A specifically tuned restrictive exhaust system can alleviate this somewhat, but this is the primary reason you dont see 2 cycles going around with honking great turbo or superchargers on them (besides the small supercharger required in order for scavenging to occur properly).

        1. If you use 2 crankshafts, you can vary the timing of the two cylinders. It is not that hard to close the exhaust before the intake. Since the ports do not see any cylinder pressure, it would not be too hard to design a separate sliding system that decouples port timing from compression (at the expense of complexity).

  2. I don’t want to be that guy, but shouldn’t a working prototype be a prerequisite for getting a Hackaday article written about your project? Don’t get me wrong I like what he’s thinking about trying to do, but he hasn’t actually done anything yet.

      1. I disagree for the reason that the Hackaday Prize page states:

        “HERE’S HOW TO GET STARTED – It all begins by sharing an idea. Your idea can even land you a prize! Start your project on Hackday.io by writing about a problem you are trying to solve and some ideas on how you might get there. Be sure to add the tag 2015HackadayPrize to the project to be considered for early prizes.”

        If it had stated “share a complete working prototype” I would not have posted anything. Just trying to get a project in motion that could help others.

    1. true, but you have to start somewhere. Some prototypes are easy to make, other are hard (hence the name hardware). If the result of this discussion would be: ‘nah, just built a conventional engine first and open source those plans’ then wouldn’t you be happy you had no prototype yet?

    1. Yup, nuclear power is the only way to go. No hydrocarbons to deplete or biomass to use up valuable farmland.

      Thermodynamics dictates that every technology is unsustainable. Your brain metabolized glucose to read this and contributed to the heat death of the universe.

        1. The side effect of mining tons and tons of earth to obtain rare-earths and special metals such as indium and gallium for solar panels and the like is mountains and mountains of thorium and uranium, which have to be handled as nuclear waste because they are.

          So ironically, the construction of renewable energy sources produces far more waste indirectly than nuclear power itself.

          1. In fact, one of the reasons why everyone’s interested in thorium power today is because we’ve already got mountains of the stuff and nothing to do with it.

            Australia for example has 489,000 tonnes of it as a waste product of other mining activity.
            The US has 400,000 tonnes, India has 319,000 tonnes, and the piles keep growing all the time as more materials are dug up for electronics production. China doesn’t even keep count – they just dump it somewhere.

            It’s practically free energy, but as long as nothing is done with it, it’s basically a costly nuisance or an ecological disaster.

          2. For a comparison, one metric ton of thorium produces about 10 Terawatt-hours of electricity.

            One truckload will supply a country the size of Germany for a whole year.

          3. actual solar is NOT based on indium gallium… btw still have to answer where to deploy radioactive wastes; CO2 is still nicer waste than plutonium.

    2. no, only fossil hydrocarbon based combustion engines are non-sustainable. Hydrocarbons are a pretty stable form to store energy. It is only too bad that both the biological or the nuclear/chemical pathways to produce them are pretty inefficient.

  3. con:
    – rules 3 & 4

    two-stroke(simpler), diesel

    Choosing hydrocarbons as the means of “inactive” energy storage = good idea.

    High energy density, simple storage, hydrocarbons can be synthesized from various renewable and non-renewable resources. It can be hardly incinerated, (a match or a spark won’t be able to incinerate it). It can be stored for a long time.
    Diesel engines when equiped with a drive shaft connected pump are self sustained during operation, however they can run away

    Rule of engineering No 1:
    Don’t reinvent the wheel. Understand it and improve it.

    If your new design is actually a forsaken design, there is a reason why it has ben forsaken, you will find it out .. again.

    Rule of engineering No 2:
    To start with complexity leads to failure. Start simple and improve. Engineering is based on a working principle and it’s steady improvement. Also this specific engine type has displayed certain weaknesses.

    1. Could be that the concept was discontinued due to economic factors and they can change with context. If you are designing for first world then you have to make a profit. If you are designing for third world then it just has to be cheap and reasonably effective. Things like power and performance which sell an engine to an executive dont really matter to a farmer with an old donkey running a mill.

  4. A diesel engine requires significant manufacturing precision, probably not to be found in any location where a conventional diesel engine is unaffordable. Translated: the design is the easy part.

    1. True, but an open design allows many machine shops compete over who can make the parts for less, driving to cost of the engine down.

      I don’t know if there is much to gain. Most modern diesel motors are so expensive because of the environmental laws requiring stuff like EGR and DPF.

      A quick look on aliexpress and I’m seeing small motors for as little as $226. I’m not sure I could buy enough steel to build a motor for that price.

      1. Errrr…you should check the shipping costs on the “$226” motor – the one I’m looking at is “US $605.97 to United States via DHL” giving a total price of 831.97.

        Classic shipping-charge hustle you see on EBay and Amazon; free product & outrageous “shipping” all paid to the seller.

        1. Or you could go to Harbor Freight Tools and pick up a $119 dollar engine. Oh wait, you wanted a diesel? Order a container full and pay $2500 to ship as many as you can jam in there. Back of envelope calculation, 8$ each for shipping.

          Want to bet you can already buy ‘affordable’ small diesels anywhere you might need them?

  5. But this is nothing new, and how is a diesel now “open source”? It has always been that way, if you could build it then it is yours. I think with a little more effort you could find a better post, like sterling motors for third world use. I would find the link but that’s your job.

    1. What will make this “open source” is that once the design is finalized I am willing to release my CAD models, technical data, G-code, etc. so that anyone with the know how and ability can build the exact same motor. Stirling motors are great, I love them! But they are not practical for things such as well drilling equipment, personal transportation, etc.

      1. Oh but building a motor from scratch is practical. Not using the any motor will do approche just won’t work any more. Do you know that your motor would be illegal to operate in places like North America because of the gross amount of pollution it will make? Instead of an opposing piston 2 cycle, try making a normal 4 cycle motor that will be far more reliable and make better power for the fuel used. The opposed piston layout is for the most part junk, the world moved on for a reason.

  6. When I read the topic announcement I thought the down side of this year’s HaD Prize was going to be this sort of project, and things like the EM engine, impractical vaporware that either can’t work or isn’t really workable as the competitors try to stake out Big Impressive Problems.

    In this case there is of course a long and storied history of the making of IC engines and it is (a) unlikely the OP will make any really major innovation and (b) unlikely the OP will succeed in building a working engine at all, as most people who try fail the first few times. In particular I suspect this design has problems with heat dissipation.

    I realize it is not completely fair to normal hack projects to require a prototype at this point for entry, but there really should be a mechanism for separating the moonshine from projects that are actually likely to result in a prototype within the year of the contest.

    1. Hence there is a best product category that separate “looks good on paper” from the “hastily duct taped prototype”, to the ones that can be duplicated and make as an actual product.

      There is a bit of trade off to the types of problems that you are trying to solve. The diesel engine or some of the more noble projects we have seen so far might get to the duct tape stage, but having to make 3 samples of the working product in the time frame is not likely unless you have the finances, skills and tools to do it.

      I don’t have the vision to change the world, but I do know a few things about making products. So I am putting my efforts on the product side.

  7. There is nothing in this. A guy posted one single paragraph stating that he’s designing an open source diesel engine. Nothing more.

    Well, it just so happens that I am designing an open source fusion reactor to power wheel chairs for lovely old ladies. It can also be used to unmelt the polar ice caps. That’s all. No more details yet unfortunately. Can I have an article too?

  8. Make a Lister CS clone that’s lighter &/or cheaper. Investigate a clean/cheap/SIMPLE farm engine & don’t discount the work of Sterling/late 18th century US and semi-current Chinese farmers.

    1. You’re right. It takes a lot of engineering to create a diesel that has low pollution and this looks like it comes from the opposite end of that spectrum.

      Some people think that pollution is ok for the third world as long as it makes things cheap. I disagree, of course.

  9. Has anyone actually tried to construct a working piston engine in a home shop? It’s next to impossible! Even two stroke engines are difficult to engineer, and an engine with twin crankshafts that require sophisticated timing mechanisms is not something that people in areas without available engines will be able to fabricate!

    I hate to be the one to say “this will never work”, but this will never work.

  10. It was Volvo or Saab that had developed/patented a variable compression engine, and it was indeed simple, the block(cylinders, heads and what not are mounted on an hinge, on the other side there the crankshaft, an electric linear actuator varies the angle of the hinge, and presto: variable compression ration, the thing is that it causes uneven wear in the piston skirts, and you get funky asymmetric timings.

    1. It was SAAB. GM forced them to shelve the design in ~2003 because of its cost. Either GM or BAIC (who bought most of SAABs engine and engine management properties in 2008) is sitting on the patents for that design, letting them rot.

  11. And there are lots of simple diesel engines, at home we have a Lombardini single cylinder four stroke diesel engine used as a backup generator, the engine is rated at 12 or 16kW, with 640cc displacement, it has two valves, a simple mechanical injection system and a governor to keep the rpm’s more or less the same under load, it hates having all our 3 phase motors running, and CCFL’s flicker a bit, but when there is a power outage its a blessing, it has forced air cooling, but can be run for days, the best part, consumes about 4l of diesel per 6 hours.
    The downside: the exhaust has long since rusted, so its very, very loud, but who cares.

  12. A semidiesel / hot bulb engine would be far more practical, low compression, can run on almost any liquid fuel, and does not have a very high pressure fuel pump that has to be made to fine tolerances like a true diesel. It would be much easier to make with basic machine tools compared to a true diesel.

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