Thread: Ambitious newby

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  1. #71
    I've spent most of my life being self-depreciating, and I find nobody takes you seriously. I guess I rather be thought an arrogant twat than a simplton.

  2. #72
    Quote Originally Posted by bobc View Post
    The fact is that modern machines are so complex they require more knowledge than one guy can muster, certainly if building from scratch.
    Personally I think this is one of the problems with modern technology, it is too complicated. Often I think efficiency can best be achieved through simplicity. Once a simple machine works perfectly more machines can be added to it to work in synergy, insted of add more complexity to make up for the short falls of the simpler components. That is what I am trying to do with this engine design. Could it be a complete failure? Sure, of course. It probably will be, but what I learn from that failuer will lead eventually to a success. And I think this success will come from trying unconventional ideas and from simplifying the design. Basically I have this design set up so that the only variable in operation is fuel delivery. all aspects of it's performance can be controlled by an electronic fuel injection system with myriad sensors and meters telling the computer what it needs to know to deliver the exact right amout of fuel and air pressure to achieve maximum power, efficiency, and minimum waste and emissions. What can I say? I'm a dreamer.

  3. #73
    Quote Originally Posted by brsanko View Post
    If you actually had sound advice to give you wouldn't waste your time harassing me. You're the only arrogant twat around here. You haven't given any advice, sound or otherwise, except "don't do it it's too hard".
    Ok suggest you go back and read post #4 now where does it say "don't do it, it's too hard" actually nearly the opposite.!! I even say I'm sure you'll succeed and wish you luck.!!

    You seem intent on dismissing advice from people who have made you aware of there past experience and berrating them has egotistical Nah saying doom gloom merchants just because they didn't pat you on the back or tell you what toys to buy.!!

    Now I don't give a flying fuck what some people on here (I can guess who they are anyway.!!), who don't actually know me think.!! . . .But those that do, know I'm possibly one of the most willing people to part with advice for those prepared to listen and have a bit of respect.!!. . . .They will also have gathered I'm the type that won't give you the stink off my shit if you have a bad atitude.!! . . . . Yours stinks worse than my shit so go forth and multiply. .

    *** Oh still think it fucking hilarious that you would make a major major design change because someone who probably has very little experience suggest's it.!! . . . More hilarious is that you think it's better. . ***

  4. #74
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 8 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,192. Received thanks 243 times, giving thanks to others 5 times.
    Engine design is a very complex area.
    Manufacturers are spending millions on engine design in order to meet ever stricter emissions, so don't even think it's just a case of getting the right amount of fuel in!

    Modern diesels are far more complex than their petrol counterparts.
    If you don't know what SCR, EGR, DPF, CR to name a handful are, and they're purpose, you really have a lot of research to do.

    As for the basic mechanics, extensive FEA has to be done to ensure parts are as light as possible while still being able to withstand required loads. Lots of work has to be put into thermal design to avoid parts overheating or having problematic hot spots. And finally you have to make sure the parts are manufacturable without exotic processes.

    I'm not trying to discourage you, I'm just letting you know of the lengths manufacturers are having to go to meet emissions. Each of those systems I've mentioned add substantial cost to every engine, and vehicle manufacturers are renowned for saving every penny they can, so they're not doing it because they want to, they're doing it because they have to.

  5. #75
    I understand the complexity of these things and I am trying to do as much research on these issues but there doesn't seem to be a whole lot of sharing when it comes to this kind of information. It seems like one of the biggest issues when it comes to emissions is ensuring the complete burn of the fuel while still getting as much power out of it as possible. The fact that with the scotch yoke instead of normal connecting rod design the piston spends more time at TDC this allows a more complete burn of the fuel as well as maximizing the power extracted from it. Couple that with the fact that there is less wear on the cylinder walls and pistons and rings due to a lack of pivoting, not to mention much less weight and size combining two combustion chambers in one cylinder and you have a small example of how a simplification of design can help with several issues with one "out of box innovation". I'm not by any means saying I've got it all figured out and know all the issues I'm just saying that making nonconventional designs as a hobby with no big dollar company at stake can yield results that penny pinching corperations may not even spend a minute thinking about. And if it all fails and proves alltogether futile, then I will have had a good time trying. I want to know everything, about everything, while it is obvious that this is impossible it won't stop me from trying.

  6. #76
    All of these issues and areas of research are what I am trying to learn about. I have done much researchand will do much more. The engine design I have is not a prototype, or a blue print, it is an idea. I am making it as detailed as I can so that I can understand and address all of the issues out there. I'm not presenting this and saying this is the thing! Sorry if I come across that way, I'm saying "hey I have an idea and it looks something like this, what do you guys think" I've tried finding information on emissions issues and various solutions and ideas, but honestly it's tough to find. I don't even know where to start with thermal tollerances and such. So I'm putting what I have out there and asking for help to find the rest. You have given me some things to think about and some places to start and that is what I am looking for. So keep the comments comming and be as specific as possible and please offer some sources for reasearch. Right now I've jest been looking for information from free sources, but in the near future I will probably look at buying some research material. I think everyone knows that paying for knowledge is the quickest way to get ripped off so I guess I'd like to know what the best sources are as well. I know people are going to suggest school but I really suck at school and I just can't handle spending a week learning to use the power switch and wear my safty goggles correctly.

  7. #77
    Thanks Chip. If you goto someone's profile page you can click on "ignore this person's posts" or something of the like. I've done that to Jazz and so now he can flap his gums all he likes and I don't have to see it.

  8. #78
    How about outfitting the milling machine with a rotary axis instead of getting a dedicated lathe?

    Like this -

    If it could be flipped horizontally or vertically, you could do most work on that... any ideas how to get it to do that?

  9. #79
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 8 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,192. Received thanks 243 times, giving thanks to others 5 times.
    What you're basically proposing is a boxer engine (that's the general term given to flat engines with opposing cyclinders), with a scotch yoke crank/rod set-up and ported cylinders.

    None of those havn't been tried.
    Scotch yokes are problematic, because the slightest amount of play causes knocking. Reduce the play too much, you can't get oil in and risk seizing/premature wear, too much play and you can't keep oil in and it knocks. Wear is always an issue on scotch yokes due to the sliding components, and the only practical area I've seen it used is in relatively low speed hydraulic pumps, which start knocking when worn and under load. Now given that this part of the design needs to withstand millions of cycles (a quick calculation for 10'000miles covered at an average speed of 30mph and 2000rpm, works out at 40 million cycles), it needs to be able to withstand wear.
    There is also the disadvantage of not being able to tune when peak torque is applied to the crankshaft. With a scotch yoke peak torque transfer will always occur at mid stroke, as that's when the crank pin is at 90deg to the applies power.
    With a conventional con-rod design, and by varying stroke/con-rod length, you can alter where peak torque is applied to the crankshaft, which from memory is usually around 30-40% of stroke from TDC.

    Ported cylinders also come with issues. The biggest issue being purging the cylinder of spent gases. With a 4 stroke, the exhaust and inlet strokes do that very well, whereas with a two stroke you're never going to get a clean purge. With both ports open, there is still an area of gases at the top of the cylinder which even with good porting/air flow management, isn't going to be purged too greatly.

    I'm not saying those issues aren't insurmountable, but there are many reasons why the Otto-cycle engine is still the favoured basic engine design to this day.

  10. #80
    Yes, those are all points I've considered, although I don't know much about the scotch yoke wear charachteristics as the only other place I've seen it used is the Bourke engine and there isn't much information about that. You do seem to have missed what I think is the most unique feature of my engine, the fact that it fires on both sides of the pistion essentially making it a one stroke cycle engine. The reason I think this is a good feature is that it allows a small engine to produce more power and do so at low RMP. But like I said before I really want to learn to fabricate, and if this engine doesn't work out I'll still be into metal work.

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