Author Topic: a very small 4 stroke engine : 1.35cm3  (Read 1681 times)

Offline Zephyrin

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a very small 4 stroke engine : 1.35cm3
« on: May 23, 2020, 09:48:27 AM »
I present you my last engine almost finished and running; a mini 4T of 1.35cm3, (0.08cu in) (bore and stroke: 12mm).,
I wanted a 4 stroke engine, spark ignition, with a reasonable noise level, good power and not running too fast. The goal was to get an engine capable of moving a small mechanical diesel shunter for the 45mm,  gauge 1 track at 1/32 scale more precisely.
So I designed a model inspired by some early engines with a camshaft parallel to the cylinder driven by helical gears, with also a low compression ratio, about 4.3; the cylinder head having a large combustion chamber with face to face valves, quite in the style of the Wyvern and Centaur from ET Westbury, from which I also copied the rocker arm style. The cylinder head has 2 valves controlled by rocker, but I reserve the option to test an automatic intake valve if all goes well.
I also put a water tank for cooling, rather than a water jacket and its associated pump, radiator and fan owing to limited space.
There is also a large flywheel (relatively!) for the smoothness of operation for such a small engine, leaving me the possibility to put a second one on the future drive side.
There is for the moment a traditional ignition with breaker and HT coil; I  had to make some home made spark plugs, mini too, the 1/4 x32 being too bulky on this tiny cylinder head, especially with the carburettor too close to the spark plug, not easy to adjust air intake without receiving electric shocks!
After a rather long running-in, mostly because of my "shop-made" helical gears, it has no more stiffness and started easily, responds well to settings for air, fuel and ignition timing, and runs like a clockwork, but alas, far too fast for my taste, between 2500 and 5500 rpm, the noise being not the expected "put-put-put", but in an acceptable range.
I’ m actually doing an electronic ignition and rebuilding a more advanced carburettor than the simple mixer, and do some power tests to see if the rest of the program is feasible.
but I'm currently making an electronic ignition from a gas lighter as shown in the Jan Ridders website.
I’m also drafting a final version of my plans, but I’m not expert in this field !
I will post some pictures of the building of my engine, after the final result, I agree that this is not the usual way to proceed, but I have to select lot of pictures in my computer…




Offline Roger B

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Re: a very small 4 stroke engine : 1.35cm3
« Reply #1 on: May 23, 2020, 10:27:13 AM »
Excellent  :praise2:  :praise2: Fitting a spark plug and valves into a 12mm bore is not easy. Did you use piston rings?
Best regards

Roger

Offline MJM460

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Re: a very small 4 stroke engine : 1.35cm3
« Reply #2 on: May 23, 2020, 01:00:37 PM »
Congratulations Zephyrin on a great runner.  It is a really neat and compact design.

MJM460

The more I learn, the more I find that I still have to learn!

Offline fumopuc

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Re: a very small 4 stroke engine : 1.35cm3
« Reply #3 on: May 23, 2020, 02:12:10 PM »
Hi Francois, very nice.
I should put something similar on my retirement list.

Kind Regards
Achim

Offline nj111

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Re: a very small 4 stroke engine : 1.35cm3
« Reply #4 on: May 23, 2020, 04:15:15 PM »
That is fabulous! Thank you for sharing here.
Nick

Offline awake

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Re: a very small 4 stroke engine : 1.35cm3
« Reply #5 on: May 23, 2020, 05:16:42 PM »
Wonderful sound - so even and consistent. Congratulations!
Andy

Offline Admiral_dk

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Re: a very small 4 stroke engine : 1.35cm3
« Reply #6 on: May 23, 2020, 07:30:44 PM »
Impressive that you got it running so well with such a small design  :praise2:

Offline Art K

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Re: a very small 4 stroke engine : 1.35cm3
« Reply #7 on: May 23, 2020, 11:25:39 PM »
Zephyrin,
You have built quite a nice running engine. I hope it works for your shunting engine!
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline Craig DeShong

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Re: a very small 4 stroke engine : 1.35cm3
« Reply #8 on: May 23, 2020, 11:27:43 PM »
Not a lot of room for miss fit machining with a displacement so small.  Runs and sounds great!  Superb job :ThumbsUp:
Craig

Offline Zephyrin

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Re: a very small 4 stroke engine : 1.35cm3
« Reply #9 on: May 24, 2020, 08:19:01 AM »

Thanks for all these appreciations and comments,
My engine is not as small as the famous "tiny" published some 10 years ago by putputman, with its 3/8" bore, and its superb hit & miss versions by Gail Graham and Georges Britnell, unsurpassed...

You are right Craig, but you can note that I left some length on the camshaft for a centrifugal regulation, I read and learn avidly on this forum...

A hit & miss control would certainly make the sound more realistic for a small shunting loco, between idle and loaded...but as I have difficulties with the carb, I hesitate to add further trouble with a hit & miss control !

No Roger, no piston rings, a long and plain cast iron piston with 4 oil grooves.
I will post some pictures of the parts.

Offline Zephyrin

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Re: a very small 4 stroke engine : 1.35cm3
« Reply #10 on: May 28, 2020, 09:28:15 PM »
I put some pictures of the building of my little engine on my Google album

https://photos.app.goo.gl/aDQ5aQCqALkuMuGs9

I tested the electronic ignition made with a gas lighter as shown by Jan Ridders on his website, and it worked a treat,
I will do a neat lttle ignition box to replace the ugly coil and cable...


Offline Roger B

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Re: a very small 4 stroke engine : 1.35cm3
« Reply #11 on: May 29, 2020, 07:52:49 PM »
At the end of this link there are some pictures of Johan van Zanten's Gauge 1 Deutz mining locomotive with a 2cc engine.

https://www.model-engineer.co.uk/albums/member_album.asp?a=6778

It was also written up in MiM,

https://www.vth.de/maschinen-im-modellbau/unsere-beitraege/minenlok-mit-verbrennungsmotor


Best regards

Roger

Offline Zephyrin

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Re: a very small 4 stroke engine : 1.35cm3
« Reply #12 on: May 29, 2020, 09:17:36 PM »
Thanks for the links Roger, spot on.
magnificent model, impressive work, a tiny Hit and miss to drive this little Deutz shunting loco, very akin to the models of Gail Graham.
A hit and miss engine is probably more comfortable to use...
but as my engine is running now, I will have a go with my version of the shunter, making a H&miss version of my engine would be a spare wheel, just in case...

Here  is the link for the PDF of the plan my little 4St engine.

https://ti1ca.com/7dzxwa8z-Gedeon-4T-v2-Gedeon-4T_v2.pdf.html

FM

Offline MJM460

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Re: a very small 4 stroke engine : 1.35cm3
« Reply #13 on: June 01, 2020, 11:48:01 AM »
Hi Zephyrin, a beautiful little engine which will look and sound fabulous in your locomotive.

I have been thinking about the issue of governing the hit and miss action, and can understand that the tiny size might mean that governor weights will have too little mass to operate the valve latching mechanism.

Hidden in your locomotive body, a little electronic governor might be able to operate a mini-servo for the valve operation to get the miss part of the action.  You might be able to get pulses for a “count” for rpm by shining an infrared LED through holes in a gear wheel, or special wheel, onto a photo transistor.

There would be no need for a complex PID algorithm, simply a switch between two servo Positions based on high and low rpm limits with some hysteresis.   

The electronics can be made quote small, and you already have a battery on board if the processor power can be separated from the ignition system, otherwise a separate 4.5 - 4.8 V battery pack.

It could be easier to implement and more reliable than a conventional mechanical governor in such a small size.

MJM460

The more I learn, the more I find that I still have to learn!

Offline Zephyrin

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Re: a very small 4 stroke engine : 1.35cm3
« Reply #14 on: June 04, 2020, 02:50:27 PM »
Hi,
Thanks for advice MJM,
electronics, well, actually, I just dropped my homemade electronic ignition, really unreliable in my hands, I'll work on that...later.
But there are example of working " tiny" H&M regulated engine, by G. Britnell & Gail Graham, 3/8" bore size, that small!

I've rebuilt a new carb for my "Gedeon" engine, I don't receive electric shock anymore during the tuning of air and gas...phew!
I could add a tiny hole for air bleed when idling, to limit smoke, or make a new carb, in steel and longer to prevent vapour lock
my engine run fine, I'm having fun with it : I will do tests for a gear train for transmission...


But I find the torque a little bit just to move a loco forward, she will stall constantly...but I'm only at the beginning of the tests.

Cheers