Lightest diesel engine known to man

  1. Which would that be?

    I hear diesel engines are always heavier than equivalent gasoline ones. I saw some portable electricity generators the other day, and the truly portable ones were all gasoline-based.

    What's the lightest diesel-based electricity generator you know?
     
  2. jcsd
  3. Mech_Engineer

    Mech_Engineer 2,299
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    Saying that "equivalent" diesel engines are always heavier is somewhat misleading; how are you defining their equivalence? Displacement? Horesepower? Torque?

    The reason diesels are usually heavier on a per-displacement basis is because they deal with much higher compression ratios (over 20:1 instead of 9:1) and so have to have much stronger internal components and blocks to deal with the higher pressures. However, a diesel will also have more torque than a similar displacement gasoline engine.

    Small Diesel engines do exist. Take for example, this roto-tiller:

    http://www.minelinks.com/tools/diesel-tiller.html
     
  4. NateTG

    NateTG 2,537
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    I'm not sure what the original poster meant by 'light'. Despite weighing 1300 pounds, this could be considered a light diesel engine because it has high power density
    http://en.wikipedia.org/wiki/Junkers_Jumo_205

    1-2 cc compression ignition models are popular for modelers e.g.:
    http://www.modelenginenews.org/mate/index.html
     
  5. Mate-1.jpg

    This is amazing!

    I was just looking for a diesel-fueled electricity generator that is as light as possible. The lightest diesel engine that exists for a rated output of 1-3 kW. Which would that be?
     
  6. brewnog

    brewnog 2,793
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    You can get a little 2.5kWe Yanmar genset which weighs about 65kg. Whether this is the smallest/lightest known to man, I have no idea. Those model engines are pretty small, but I imagine someone's done a nano-scale one.

    What is your application?
     
    Last edited: May 21, 2008
  7. NateTG

    NateTG 2,537
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    No clue. That's 1.5-5 HP. I know that there are manufacturers that sell diesels in that size range. Regardless, I expect that it's usually going to be cheaper and easier to look into an off-the-shelf solution for your generator.
     
  8. I want something that I can easily carry with me outdoors for powering tools, pumps, water purifiers, maybe a fridge. Actually I may need more than 3 kW later, but portability is essential at this stage.
     
  9. How much power does a small aircraft need?
     
  10. brewnog

    brewnog 2,793
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    Well have a look at what power demand you need. Why you you want diesel rather than petrol?

    How big is a small aircraft? The smallest I made was quite happy being propelled by a rubber band.
     
  11. A real aircraft I meant. We've seen a model aircraft's engine haven't we.
     
  12. Mech_Engineer

    Mech_Engineer 2,299
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    There are definitely off the shelf protable diesel generators in your power output range. Saying you want the generator to be "the smallest known to man" is somewhat misleading as it insinuates price is not an issue and you need it to be super, super small. When you say you want it to be light, how light? It seems to me that generators in the 3kw range will weight about 100-150lbs, so that's pretty much what you will be looking at...

    Here is a nice looking 4kw Diesel unit, weighing in at 120lbs:
    http://www.peakpowertools.com/Portable-Generator-Diesel-Pramac-3700-Watt-4kW-p/gpr04601.htm

    If weight is of supreme importance (as in you need to be able to dead lift it by yourself), it's likely you'll be stuck with a 1-2kw gasoline-powered unit that weighs less than 100lbs. If you don't mind rolling a generator around, then you can pretty easily move a 150 lb model. Because gas generators are so much more common, they are available in smaller peak outputs as well as much lower prices.
     
    Last edited: May 21, 2008
  13. Because diesel engines require less maintenance, and are more reliable. Also I think I can make the fuel myself, if things ever get this bad. 99.9% ethanol is much harder to make from vegetables.
     
  14. I didn't say light, I said the lightest known to man. Expected some alternative alloys being used, dunno what those model-aircraft ones are made of, probably not steel.
     
  15. brewnog

    brewnog 2,793
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    So, your requirements so far:

    - Lightest diesel engine known to man, installed in a generator
    - 1-3kW electrical power
    - Low maintenance
    - High reliability
    - Tolerance to 'home made' fuels
    - Portable enough to be carried alone?

    If you find some way of prioritising those, let us know; because many of them are direct trade-offs.
     
  16. brewnog

    brewnog 2,793
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    By the way, the traditional benefits of Diesel engines of reliability and low maintenance (as compared SI engines of equivalent output) don't really hold true on a very small scale.

    A lot of reliability tends to be "designed in", rather than being an inherent feature of the fuel type itself; and then it's usually on industrial, medium/heavy duty engines where weight is not a primary consideration. Low maintenance is primarily a result of mechanical simplicity (as well as oil life), but these advantages tend only to be seen when running larger engines for long periods of time (thousands of hours); and very small SI engines are simple affairs anyway.
     
  17. That's cool, thanks. Regarding priorities, let's start with the lowest weight currently available at this power rating, subject to the contraint of diesel as a fuel. I'm sure that's from an aircraft engine.
     
  18. Mech_Engineer

    Mech_Engineer 2,299
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    There are no diesel aircraft engines available in the power rating you've specified. The specification is too big for R/C applications, but too small for ultralight aircraft applications. Most ultralight planes use 50-100hp engines that run on aircraft-grade fuels, not diesel.

    I think you're basically looking for the lighest commercially-available diesel generator in the 1-3kw range. Such generators will probably weigh in at a minimum of 80 pounds. You're not going to find any diesel generators that use all-alloy blocks because cost is far more important than weight for a generator.
     
  19. brewnog

    brewnog 2,793
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    Good advice.

    http://chinaxingyue.manufacturer.gl...gine/1001030490/Air-Cooled-Diesel-Engine.htm#

    That's pretty lightweight, but you'd have to build it into a generator yourself.
     
  20. Look at the rototiller you mentioned, it weighs just 70 lb with all the equipment.

    miniature-tiller.jpg
     
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