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Thread: the clean two-stroke thread

  1. #136
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    Quote Originally Posted by ken seeber View Post
    One doesn't feel too bad when you might consider adding a few injectors or a valve onto a 2 stroke

    Attachment 346647Attachment 346648


    Instead, I think the opposite, which should not be added, what should be done is to simplify what is already there. What there is is good, but if it is simplified we will do it twice as good.
    That is why I have dismissed the DI concept as the only solution and start focusing on SDI.
    I want to evolve the QUB Hill and Blair concept (it's like a TPI but without the electronics)
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  2. #137
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    Quote Originally Posted by ceci View Post
    Instead, I think the opposite, which should not be added, what should be done is to simplify what is already there. What there is is good, but if it is simplified we will do it twice as good.
    That is why I have dismissed the DI concept as the only solution and start focusing on SDI.
    I want to evolve the QUB Hill and Blair concept (it's like a TPI but without the electronics)
    Is having an ecu on board such a bad thing?
    Ecu with injectors can do a lot that a carburetor can not, way more fuel control and some interesting engine control too.

  3. #138
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    Quote Originally Posted by Flettner View Post
    Is having an ecu on board such a bad thing? Ecu with injectors can do a lot that a carburetor can not, way more fuel control and some interesting engine control too.
    I remember the last carbureted Honda cars. In order to make those carburetors behave as required under all circumstances, they had become incredibly complicated.
    Yet their ECU-controlled injected successors were better in every way and possibly cheaper as well. Mechanically-controlled injection certainly wouldn't have been...

  4. #139
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    Quote Originally Posted by Flettner View Post
    Is having an ecu on board such a bad thing?
    .
    It is expensive and heavy, since it is not only the ECU but also the sensors, pump, injectors, battery and others.


    Quote Originally Posted by Frits Overmars View Post
    Mechanically-controlled injection certainly wouldn't have been...
    Not to be necessarily mechanical

  5. #140
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    Quote Originally Posted by ceci View Post
    Not to be necessarily mechanical
    If you do not control the injection electronically and not mechanically, then what else is there? Just a pump coupled to engine rpm? Surely that won't do.
    (With 'mechanically' I meant 'with moving parts' , like a centrifugal governor, a pressure-sensitive bellow, a springloaded hinge moved by air flow, etc.)

  6. #141
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    Ceci,

    I do like the Blair simplicity as much as I do like the Husqvarna X-Torq. Essentially incorporating some clever separation and re-routing of the scavenge system without much extra hardware. However, I just don't know if, for instance, this was applied to a bike, could this get anywhere near Euro 4 or 5.

    I posted the BMW cylinder head as an example of the lengths that manufacturers are going to meet driveability, performance and also meet emission goals. I was just amazed at the complexity and number of fiddly components in the design. Yep, I'd hate to see that the 2 stroke has to go to such lengths to become clean, may just as well just go with volts and amps.

    Personally, I do (unfortunately) think that we have to accept a greater level of complexity to become clean.

    No misfiring for us.
    "Success is the ability to go from one failure to another with no loss of enthusiasm.”

  7. #142
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    Quote Originally Posted by Frits Overmars View Post
    If you do not control the injection electronically and not mechanically, then what else is there? Just a pump coupled to engine rpm? Surely that won't do.
    (With 'mechanically' I meant 'with moving parts' , like a centrifugal governor, a pressure-sensitive bellow, a springloaded hinge moved by air flow, etc.)
    You refer to this employee a century ago in Goliath CP 700 engine which is from Bosch.




    In exchange I mean this Spanish (I know you understand Spanish, but I don't know if you know how to read it, that's why I will try to translate it "googletraslate" (The system is made up of three parts: two pumps, one of membranes (with carbon fiber sheets) and another line, and an injector.
    The first is located behind the rear transfer of the cylinder and through a hole made in it sucks the gasoline from the tank taking advantage of the upward stroke of the piston. When it goes down, it creates a compression in the crankcase, from which a fitting emerges that drives the piston pump, located after the first pump and sends the mixture to the injector. This, coming from a kart carburettor with a carbon fiber guillotine, thus receives an injection of constant fuel, self-regulated by the engine rotation speed.
    The whole secret of the operation of such a simple and ingenious system lies in the adequate calculation of the surfaces and diameters of the two pumps, to take advantage of the internal pressure and depression effects of the two-stroke engine.) )





    It doesn't have to be a very bad idea when big companies have copied it,

    https://patents.google.com/patent/US...+stroke+engine




    https://patents.google.com/patent/FR...+stroke+engine

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  8. #143
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    Quote Originally Posted by ken seeber View Post
    Ceci,

    I do like the Blair simplicity as much as I do like the Husqvarna X-Torq. Essentially incorporating some clever separation and re-routing of the scavenge system without much extra hardware. However, I just don't know if, for instance, this was applied to a bike, could this get anywhere near Euro 4 or 5.

    .
    If KTM is approved for Euro 4, the QUB also, since neither system uses transfer A


  9. #144
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    I do agree that some complexity will be necessary for a clean machine, but when everything is established and working properly, then it isn't "complex" anymore! (only when it is new and and needing development).

    Sure, go for simplicity if it is going to make a quantum leap, but even if it is a quantum leap, there will always be attempts at development to improve it further - and you have to keep up to survive ..... and so on it goes!

    Of course, on the other hand, I have to admit that I've always been saying, the two stroke engine needs to be kept simple as possible, (using hybrid type transmission) which will then do away with the need for an incredibly flexible engine having to work perfectly over the whole rev range, but I'm not meaning a "spartan" thing without good fuel / charge management etc etc.!

    My next crusade? get rid of Schneurle type transfer, expansion chamber and crankcase pumping! ........ OP? - Yes, (already proven to be efficient) - Turbo? - yes, I think so, (initially being spooled up by a motor for startup) - turbos are small and fast becoming a dime a dozen !

    Yes we are matching emission requirements today, but they are continually raising the bar and one day our good old "normal" two stroke won't be able to keep up! - remember that realistically the two stroke in it's present form is hanging on by it's fingertips!

    BTW, these suggestions are not all only my ideas, a lot of them come from ideas which I have gleaned from others here!

    Anyway, that's how I see it!

    Then, last but not least ..... what has happened to Haufen? - the originator of the thread!
    Strokers Galore!

  10. #145
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    You will wonder why these types of injection systems were unsuccessful.

    The Martin Clerch is an INDIRECT injection with which the short circuit and the loss of hydrocarbons by the exhaust are not avoided, it is also injected when there is no current, since when the piston falls if compression is created in the crankcase, but Yes No suck intake.

    Stihl and Bosch are DI, which is not compatible with this type of pump as it pumps before TPO, and DI requires pumping after EPC.

    In drawing 2, Bosch is more suitable for DI as it uses suction from the crankcase to pump
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  11. #146
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    A long time ago the Rolls Royce Crecy used Bosh direct injection mechanical pumps like those used in diesel engines. The injection was timed to spray into the intake flow with a dribble into a prechamber to give a rich mixture at the plug. Throttling was bu varying the amount of fuel in the primary injection. It worked for aircraft applications but wouldn't have the power band for road applications. Mechanical injection pumps might be simple, but they require high precision manufacturing. Integrated circuits are complicated internally, but are made with much lower cost methods today. They have proved to be reliable and adaptable in automotive applications. Mass produced injectors and engine management electronics are readily available. Why not use them?

    Lohring Miller

  12. #147
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    Quote Originally Posted by lohring View Post
    A long time ago the Rolls Royce Crecy used Bosh direct injection mechanical pumps like those used in diesel engines. The injection was timed to spray into the intake flow with a dribble into a prechamber to give a rich mixture at the plug. ......................... Mechanical injection pumps might be simple, but they require high precision manufacturing. .................. Integrated circuits are complicated internally, but are made with much lower cost methods today. engine management electronics are readily available. Why not use them?

    Lohring Miller
    Electronics is here to stay, things which 20 years ago were an advanced idea, are now something which everybody uses (ho hum) - they do a good job and are seriously cheap - (but are we any happier?).

    Let's look at a good example, the 3D printer, essentially a very simple machine which any engineer could construct easily.
    This did not come into it's own till sophisticated electronic controllers and software to control the control hardware itself came into being, then suddenly it all blossomed and now every man and his dog has one - and what do they use them for ? - printing skulls and other grotesque "childlike" ornaments.
    These things complete can currently cost under NZ $400!! - now they moan about these "crap machines" and expect perfection to be handed up on a plate! - this all being the sort of stuff we would have given our left arm for just a few years ago!

    It's the same for motorcycles, use the old unsophisticated basic engine and adorn it with electronics to make it good to take on the road - but I think we have been caught napping this time and now have to work out a complete new design of "unsophisticated" engine to get going again!
    Later on, the old "Ho Hum' thing and criticism if it's not doing what it's supposed to do will start all over again - (nobody really with any idea of what it's actually supposed to do, or how it works of course!), but that's how it is and only a few of us actually have any interest in or know how things work!

    What I am saying is essentially what Lohring is saying, if it's been developed and it works well, it will get cheaper, it will serve us well (ie if we can adapt it for our uses) - all to our advantage!

    Building a very (mechanically simple) machine however will get us in the ballpark!
    Strokers Galore!

  13. #148
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    Does this mean I need to get my dog a 3D printer. LOL I love mine for prototyping off the wall ideas. With the current (at least here) opposed piston two stroke fever, I'm inspired to join two of our RC engines into an opposed piston twin. The compact design will make a great speed record engine. I doubt that I'll worry about emissions, though.

    Lohring Miller

  14. #149
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    Please enjoy my more than twenty year old proposal for the ultimate ligthweight two stroke genset.

    https://archive.vn/s7gTY/49bac5b7a1b...09943819dd.jpg

    Two wheel drive with an electric motor in front and rearwheel is within reach.

  15. #150
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    Sorry, I forget that we are already in the 21st century and that we are in the middle of the space age.

    The electronics can bring us infinity of advantages.

    I forgot that Álex Debóm was a test pilot of the aprilia RS250 and in the preseason he tuned the carburetion (electronic carburetion with "powerjet" injection map for each section using GPS)
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