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Re: O-Rings as piston rings

Posted: Wed Jul 11, 2018 9:37 am
by warmstrong1955
No doubt, that if you go outside of the recommended fit, you will have leakage problems.
And to Harold’s point, I agree. If you try to get an o-ring to the same friction ‘feel’ as a cast iron ring, it will probably be out of tolerence, and too loose of a fit.

I’d like to know how it turns out too!

Other Bill

Re: O-Rings as piston rings

Posted: Thu Jul 12, 2018 8:33 am
by tornitore45
Will report, I am still far away from that part of the construction.

Re: O-Rings as piston rings

Posted: Thu Jul 12, 2018 10:28 am
by warmstrong1955
Oh sure.....keep us in suspense....

;)
:)
Other Bill

Re: O-Rings as piston rings

Posted: Tue Jul 17, 2018 1:00 am
by steamin10
Freind past used O-rings for a Tich. His solution was polished bores and two piece piston that could be adjusted on the rod for crush on the ring. This flies in the face of the way o rings are supposed to float, but it worked famously with little drag, once set up.

Re: O-Rings as piston rings

Posted: Tue Jul 17, 2018 5:39 am
by tornitore45
used O-rings for a Tich.
Interesting, but

What is a Tich? Steam? OR IC?

Re: O-Rings as piston rings

Posted: Tue Jul 17, 2018 9:41 am
by NP317
"Tich" is a small 0-4-0 steam locomotive.
~RN

Re: O-Rings as piston rings

Posted: Tue Jul 17, 2018 2:10 pm
by GlennW
tornitore45 wrote:
Tue Jul 17, 2018 5:39 am
used O-rings for a Tich.
Interesting, but

What is a Tich? Steam? OR IC?
I'm guessing that your Hoglet is internal combustion?
Hoglet.jpg

Re: O-Rings as piston rings

Posted: Tue Jul 17, 2018 3:54 pm
by tornitore45
The Hoglet is so called because is a V twin loosely inspired by the Harley Davidson engine.
Love the picture.
In Italy we call that a Porchetta once is stuffed and roasted.

Re: O-Rings as piston rings

Posted: Tue Jul 17, 2018 4:25 pm
by GlennW
Italy, what a great place!

Some day I'll make it back there.

Re: O-Rings as piston rings

Posted: Wed Jul 18, 2018 1:18 am
by Harold_V
tornitore45 wrote:
Tue Jul 17, 2018 3:54 pm
The Hoglet is so called because is a V twin loosely inspired by the Harley Davidson engine.
Love the picture.
In Italy we call that a Porchetta once is stuffed and roasted.
And delicious! :-)

H

Re: O-Rings as piston rings

Posted: Wed Jul 18, 2018 11:11 am
by warmstrong1955
Looks like potential carnitas to me, still on the hoof, speaking of delicious!

Re: O-Rings as piston rings

Posted: Wed Sep 12, 2018 2:45 pm
by tornitore45
I used this calculator and adjust the numbers to have just over the minimum recommended ring radial compression, I settled for 12% http://www.applerubber.com/oring-gland-calculator/

It turns out the number match what Glenn W posted.
The bore is mirror finish and a funny thing I noticed.
The static friction is much higher than the the moving friction. That is a known fact but usually the difference is not too great.
I put a temporary crank on the V twin and it turn fairly smooth.

Thanks to all that helped.