Author Topic: Opposed Twin I.C.  (Read 79672 times)

Offline Brian Rupnow

  • Full Member
  • *****
  • Posts: 7575
  • Barrie, Ontario Canada
Re: Opposed Twin I.C.
« Reply #360 on: January 31, 2016, 12:12:59 AM »
Here is a nifty little trick for "old school" engine builders like myself, who still use a 12 volt battery to power the ignition on their engines. Rather than have a big ball of wire wound up with the engine when it is not in use, or two separate leads with alligator clips, I purchased a microphone connector plug at Sayall Electronics. Half of it mounts into a bracket on the engine, and half of it can be attached to the wire leads which run to the battery. The connections are solder type and can be easily connected with a small soldering gun. The lowest number of connector pins available are three, but that's not a big problem---Just use two, one for the hot wire and one for ground. The two plugs only fit together in one orientation so there is no danger of plugging it in wrong.


Offline Brian Rupnow

  • Full Member
  • *****
  • Posts: 7575
  • Barrie, Ontario Canada
Re: Opposed Twin I.C.
« Reply #361 on: January 31, 2016, 03:09:18 AM »
I have just went in and reloaded the final Youtube video, using a different format to get a crisper, cleaner video with no fuzziness. It is much clearer now.---Brian

Offline Brian Rupnow

  • Full Member
  • *****
  • Posts: 7575
  • Barrie, Ontario Canada
Re: Opposed Twin I.C.
« Reply #362 on: January 31, 2016, 03:56:02 PM »
Got my laser tach out this morning and took a few readings. The lowest idle rpm without "faltering" seems to be about 1175 rpm. this surprises me a bit because it SOUNDS slower than that. The highest rpm seems to top out at about 4000 rpm, but remember, I am running with almost zero advance on my ignition timing, and it is fixed. My timing doesn't advance as the throttle is advanced.

Offline PStechPaul

  • Full Member
  • ****
  • Posts: 688
  • Cockeysville, MD 21030
Re: Opposed Twin I.C.
« Reply #363 on: January 31, 2016, 04:34:05 PM »
I estimated the lowest speed from the sound, which seemed to have about 4 "pops" per second, to be about 60*4 or 240 RPM. In my video taken at last year's Cabin Fever, I show a tachometer on my wobbler air engine, and it shows about 200 RPM, and I figured I could get it down to as low as 120. I think there is something wrong with the way you are reading the RPM - it may be off by a factor of ten, so maybe an errant decimal point:

[youtube1]https://www.youtube.com/watch?v=8naEh12f4IE[/youtube1]

Offline BillTodd

  • Full Member
  • ****
  • Posts: 530
  • Colchester UK (where the lathes were made)
    • Bill's website
Re: Opposed Twin I.C.
« Reply #364 on: January 31, 2016, 04:37:48 PM »
I think your tacho is misreading Brian, In the first video that sounds about ten pops per second to my ear , on a twin firing every rev this equates to about 600rpm

bill

Offline Brian Rupnow

  • Full Member
  • *****
  • Posts: 7575
  • Barrie, Ontario Canada
Re: Opposed Twin I.C.
« Reply #365 on: February 01, 2016, 09:18:50 PM »
I went up to Princess Auto this morning and bought a package of 10 "supermagnets" for $6.00 ---These things are incredibly strong in their attraction to any ferrous metal and to each other. I used a .344" diameter endmill to put two shallow pockets into the top of the angles which make up the framework of the engine, and two pockets into the underside of the polished brass top plate, then used J.B. Weld to anchor the magnets in place. I certainly hope I have the magnets in the correct way so they attract and not repel!!! This should take any rattling and clattering away when the lid is setting in place on the engine. I might need three men and a bulldog to get it off to oil the engine with my squirt-can.--- J.B. Weld takes a terribly long time to "set up", at least 24 hours, so I won't know until then if I have the magnets in the right way or not.

Offline Brian Rupnow

  • Full Member
  • *****
  • Posts: 7575
  • Barrie, Ontario Canada
Re: Opposed Twin I.C.
« Reply #366 on: February 01, 2016, 09:22:45 PM »
I think your tacho is misreading Brian, In the first video that sounds about ten pops per second to my ear , on a twin firing every rev this equates to about 600rpm

bill
Bill--I took the front hand-wheel off the engine (this was covered in black tape and had one of those silver stick on targets for the laser tach) and mounted it to a 3/8" shaft in the chuck of my lathe. The laser tach agrees with my rpm readout on the lathe, so I think it is reading accurately. I am a bit surprised, I was sure the engine was running slower than 1175 rpm. at "idle"---Brian

Offline Brian Rupnow

  • Full Member
  • *****
  • Posts: 7575
  • Barrie, Ontario Canada
Re: Opposed Twin I.C.
« Reply #367 on: February 02, 2016, 01:49:37 PM »
I sneaked downstairs this morning and filed/sanded the excess j.b. weld away and tried the brass top plate for fit. It snaps into place very solidly--and is easy enough to remove that I won't need the bulldog!!!.---Brian

Offline Brian Rupnow

  • Full Member
  • *****
  • Posts: 7575
  • Barrie, Ontario Canada
Re: Opposed Twin I.C.
« Reply #368 on: February 02, 2016, 04:07:45 PM »
Jason--have you taken any tach readings on your twin to see how slow it will idle?---brian

Offline Jasonb

  • Full Member
  • *****
  • Posts: 9466
  • Surrey, UK
Re: Opposed Twin I.C.
« Reply #369 on: February 02, 2016, 04:17:54 PM »
Sorry Brian not had a chance to see what its doing, I still need to get round to sorting out an oil baffle so it will run consistantly on two cylinders. Once I know an engine runs I kind of loose interest and move onto the next one, or two or Th :-[

Offline Brian Rupnow

  • Full Member
  • *****
  • Posts: 7575
  • Barrie, Ontario Canada
Re: Opposed Twin I.C.
« Reply #370 on: February 02, 2016, 08:11:26 PM »
This is it!!! The polished brass top plate with the embedded magnets fits snugly in place, doesn't rattle when the engine is running, and yes, I can lift it up to remove it with my fingers. This will be my last post about this engine unless I am answering a question in response to someone. It's been a fun ride!!!---Brian

Offline Admiral_dk

  • Full Member
  • *****
  • Posts: 3752
  • Søften - Denmark
Re: Opposed Twin I.C.
« Reply #371 on: February 02, 2016, 09:24:48 PM »
Another fine runner from you  :praise2:

and a great ride for the rest of us  :)

Offline Art K

  • Full Member
  • ****
  • Posts: 1761
  • Madison, Wisconsin USA
Re: Opposed Twin I.C.
« Reply #372 on: February 03, 2016, 01:24:37 AM »
Brian,
Your twin runs great! It reminds me of my R90S.
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline Brian Rupnow

  • Full Member
  • *****
  • Posts: 7575
  • Barrie, Ontario Canada
Re: Opposed Twin I.C.
« Reply #373 on: February 03, 2016, 10:30:54 PM »
I have been asked on one of the forums I post on about the temperature of the engine, and how effective the fan blades on the outside of the flywheel are at cooling the engine. I had a devil of a time hunting down my remote sensing laser pyrometer, but I found it hidden in the bottom of a drawer. (It's not something you use all that often.) The engine will run exactly 10 minutes at a fast idle on one tank of naptha (Coleman fuel). Temperatures were taken during the last minute of the run. The cylinders run at 150 to 170 degrees F. The base of the exhaust stacks measure at about 185 degrees F. The ambient air temperature in the room is about 65 F---(I had my office door open to keep from gassing myself.) I would say that the cooling vanes on the flywheel are very effective with readings like that.I checked my tachometer against the readout on my lathe, and the tachometer agrees within 3 rpm of the readout on the lathe, so I guess that pretty well confirms that the lowest idle speed of the engine is around 1200 rpm, although it certainly sounds slower than that.

Offline Brian Rupnow

  • Full Member
  • *****
  • Posts: 7575
  • Barrie, Ontario Canada
Re: Opposed Twin I.C.
« Reply #374 on: May 08, 2018, 11:50:27 PM »
I am reviving this old thread because I recently had a gentleman from USA want to purchase a set of plans for it. This involved opening about 70 Solidworks CAD drawings and saving them as .pdf files so they can be opened and printed without any specialized software. If anyone is interested in purchasing a set of these plans, I sell the complete set for $25 Canadian funds. Contact me at brupnow@rogers.com if you are interested in purchasing a set of the plans.--Brian Rupnow

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal