2 cycle rotary valve engine

Discussion in 'Plans' started by nx06563, Oct 3, 2019.

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  1. Oct 3, 2019 #1

    nx06563

    nx06563

    nx06563

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    I have built several 4 cycle engines and would like to learn about 2 cycle design concepts. I have also looked at an article on a split single 2 cycle and understand the concepts but don't know 2 cycle design well enough to think about designing one. Port timing is evidently just short of rocket science.

    Does anyone have plans for a 2 cycle with a rotary valve. I am looking for a design with a disk valve and not a shaft rotary valve. I built a version of a Jan Ridders engine with a shaft rotary valve and it was a nightmare to get running.

    Thanks for taking time to read.

    Hogan
     
  2. Oct 3, 2019 #2

    rklopp

    rklopp

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    The Nalon Viper is a disk valve “Diesel” 2-stroke. Ron Chernich published the plans. I built two, a Mark I and Mark II. They look great, run great, are powerful, and LOUD! Being compression ignition, they require accurate machining.

    http://www.modelenginenews.org/cardfile/viper.html
     
  3. Oct 3, 2019 #3

    WOB

    WOB

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    There is not too much to be found on rear rotary disc valves, but here is what I discovered: http://modelenginenews.org/index.html
    On the index page, scroll down to " Engines" and expand that topic. You will see "model engine development" and under that will be "Constructing a Replica Super Fury" . Under that, rear rotary disc valves are covered in some detail. Next, back on the index page, go down to "Design Center" under "Resources" Look at "Hot Engine Design". There is useful info on valve timing. Also look at "Model Engine Development part II".

    If you digest all this stuff, you should be able to design your own rear rotary disc valve induction to convert most any conventional model 2-stroke that originally had a shaft valve. I know of no published plans available for a rear rotary valve glow-ignition engine that have been published. I was not interested in a diesel, so I did my own. I successfully converted a Jones 605 ( http://www.hemingwaykits.com/acatalog/Jones_605___Colin_Jones.html ) to rear rotary disc valve and it runs very well.

    WOB
     
  4. Oct 4, 2019 #4

    XD351

    XD351

    XD351

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    Some of the ATOM series of engines ( atom 3 and 5 ) are rotary valve spark ignition two strokes designed by Edgar t. Westbury and he also designed a boxer two stroke with a rotary valve ( i think it was called champion ) IMG_0051.JPG IMG_0051.JPG
    The photos show a version i made from barstock a few years ago -it was the first IC engine i ever built and from drawings i got from a supplier here in Australia , i also bought castings but they were unusable and the plans were almost indecipherable.

    I had a look for my plans of the craftsman but can’t find them but they are available from E&J Winter boulton scale models . Current price was $25au but I can’t say whether they would post overseas .
    You could also look around on ebay or the like and try to pick up a used twin aero engine and base your designs on it , there are many that used rotary valves ( i believe the wasp was one ).
    With the craftsman i found the crank design extremely problematic as it is a bolt together job and i found that when the engine fired it would twist and cause the engine to seize - i ended up tig welding it but that led to distortion and a lot of work straightening it , one day i might go back in and make a new crank and silver solder it together .
     
    Last edited: Oct 4, 2019
  5. Oct 4, 2019 #5

    Bazzer

    Bazzer

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    Hogan

    With regard to starting characteristics there really is no difference between a shaft valve two stroke and a disk valve of the same cylinder configuration.

    You can get an engine running without resorting to rocket science on inlet porting, exhaust port timing on very high performance two strokes with a tuned length pipe is another thing though.

    I have not built complete engines but have built disk valve conversions for high performance two strokes (6.5cc, 4.5 Bhp, 32,000 rpm) I will dig out photos and drawings this evening.

    Regards

    Barrie
     
  6. Oct 4, 2019 #6

    lohring

    lohring

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    This is a little off topic, but I'm in the middle of writing a series on high performance, glow ignition engines. They cover the history as well as the issues that are important for performance. The first parts are below:
    namba.com/content/library/propwash/2018/october/14/ History
    namba.com/content/library/propwash/2019/april/24/ Piston & Cylinder Fit
    namba.com/content/library/propwash/2019/october/4/ Head Design

    Lohring Miller
     
  7. Oct 4, 2019 #7

    Bazzer

    Bazzer

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    Hogan

    Here are a few pictures of the disk valve that I made for the MB40 pylon racing engine, this replaced the rear induction drum valve of this prototype engine, we could never quite get as much power from the rear induction setups as the shaft valve version of this engine.

    Lohring

    Thanks for the links to your history of high performance glow plug engines, I will read these and get back to you with comments.

    Regards

    Barrie
     

    Attached Files:

  8. Oct 5, 2019 #8

    nx06563

    nx06563

    nx06563

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    WOW thanks for the response. You people have made me spend a whole day searching for the perfect project. I kind of decided on the craftsman after seeing the pictures posted by XD351.
    I found the plans (I think) on an Austrailian web site E and J Winter and have emailed them.

    Thanks for all the input.

    Another stupid question----
    Most of the 2 cycle designs are airplane type motors. Do the do well adapted to a flywheel instead of a prop? I have memories of my youth and whacking my fingers starting a Cox 049.
     
  9. Oct 5, 2019 #9

    Gedeon Spilett

    Gedeon Spilett

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    the Westbury "Kestrel" 5cc 2 st engine has an admission through rotary valve in the front of the crankdisk, obviously identical to a rear one !
    and its "Zephyr" 2.5cc as a rear valve, but I didnt see the plans
    http://www.modelenginenews.org/etw/2s/index.html

    this picture summarizes what is required to do the conversion... front vs rear valve etw.jpg
     
    Last edited: Oct 5, 2019
  10. Oct 5, 2019 #10

    Bazzer

    Bazzer

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    Hogan

    An airscrew prop has a lot of advantages, as it applies an increasing load as the engine runs faster, up to a point self limiting. A flywheel if the engine wishes will allow revs to rise to an alarming level.

    No need to whack your fingers just use an electric starter.

    Regards

    Barrie
     
  11. Oct 5, 2019 #11

    XD351

    XD351

    XD351

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    Just remember that the prop is moving air over the engine so if you run a flywheel you need to do the same with a fan .
    If you are going to build the westbury design i would take a serious look at the crank design!
     
  12. Oct 5, 2019 #12

    xpylonracer

    xpylonracer

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    Hi Lohring
    May be my system but none of those links work for me, anyone else have problems loading them ?

    xpylonracer
     
  13. Oct 5, 2019 #13

    lohring

    lohring

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    The last words describe the article's content. Be sure you don't include them in the url.

    Lohring Miller
     
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  14. Oct 5, 2019 #14

    nx06563

    nx06563

    nx06563

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    Bazzer, I understand what you are saying about using a prop vs a flywheel, but isnt engine speed controlled by a throtled carburator.

    I am lazy and usually use a model airplane carb on my engines.

    Hogan
     
  15. Oct 5, 2019 #15

    Bazzer

    Bazzer

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    Hogan

    Yes you will be fine with a carb, keep it rich at the bottom end, I have seen some RC car engines really race away on tick over if too lean, that is the last thing you want on a new engine.

    Good luck

    Bazzer
     
  16. Oct 5, 2019 #16

    raildr

    raildr

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    One of the best books on ALL engines is the 2 Stroke Tuners Handbook
    http://www.amrca.com/tech/tuners.pdf It helped me understand stuff that was beyond my old brain. I worked in a Yamaha shop way back when and Yamaha had manual on two strokes that was very good. 2 strokes amaze me, thing about the Cox TD-10. There was an .049 engine back then that screamed. I missed a chance to visit George Aldrich way back then, he was a wiz with 2 stroke engines.......
     
  17. Oct 6, 2019 #17

    xpylonracer

    xpylonracer

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    My mistake, excellent articles, looking forward to the next issue !!!!

    xpylonracer
     
  18. Oct 16, 2019 #18

    nx06563

    nx06563

    nx06563

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    Having raced outboard boats with methanol burning 2 cycles in my youth I like 2 cycles. The only problem was I knew how to work on them but didn't really understand how to modify anything to improve performance. That was a black science that I paid handsomely for.
    My quest for a twingle engine has gotten me more interested in how they work rather than just making one. First step I guess is to build one before I try to design one. I found a design in a "Motor Boys" plan book for a 2 cycle diesel airplane engine that looks like a fun build. I guess I will start there and move on to a design attempt after I get it running.
    I leave for AZ for the winter shortly so I will have to leave my shop behind for 5 or 6 months. I will continue the build of the "Owen Mate" when I return. I have converted the design to inches from metric in Fusion 360 and have the crankcase partially done.

    Thanks for all the great input. I will resume making chips sometime in April and will probably be looking for more info then.

    Thanks

    Hogan
     

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