Teflon encapsulated silicone O-rings‏
 

Has anyone used Teflon encapsulated silicone O-rings‏ when building and engine? They are supposed to be indestructible and work for both water seals and for oil control rings.

fwiw, I think Pineapple uses them.

Here' some reading for you..........

http://www.nopistons.com/forums/inde...howtopic=67208

I do have them in my car, about 15K, lots of track time and so far no problem. Pineapple's Orings are viton I believe.

Paul

Somebody's giving you bad info. Along with the nopistons thread on the Rotary Aviation TES inner o-rings having poor quality control and prone to failure, stock oil control rings work perfectly fine and the 'upgraded' ones don't last as long as stock based on everything i've read. In my opinion, if it ain't broke, don't fix it.

The pineapple rings are indeed viton (not TES) and I've used them in many of my recent builds.

http://www.pineappleracing.com/index...PROD&ProdID=99

I think, honda uses those kind of O-rings..

If Viton weren't "good enough" then I'd be sourcing Kalrez or Teflon Encapsulated Viton, not silicone.

Dave

Well I used Atkins Viton oil control rings in my rebuild so I guess I will fine out. I'm runing a full synth oil too, which is why I went with the Vinton.

Terry7

Terry,

have you read something that lead you to believe that synth would harm the factory oil control rings? This is the first I've heard something like that.

I have read somewhere that Viton works ok, but is designed to work up to 400 degree. The challenge is that it can get up to 500 degrees where the seals meet the irons. I will look for the info about Viton and temp.

In the rocket business, we use the teflon encapsulated Viton only in certain situations. In most situations, a standard elastomer like Viton or Chemraz or EP works best. Teflon is a polymer, and polymers are usually too hard to seal as well as a soft elastomer. Polymers are also worse about taking a set over time, and loosing their sealing ability compared to an elastomer.

1) Chemical compatibility - the chemical we are sealing is so reactive that straight Viton alone will get soft or swell when exposed to the chemical we are sealing.

2) Low sliding friction - if we have a rotating mechanism and we are trying to use the smallest possible power to turn it, then we use the teflon encapsulated elastomer o-rings.

Again, these are the ONLY two times that we use a Teflon encapsulated viton o-ring.
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I have had no problems with new stock Mazda oil o-rings, from street port motors all the way up to my 370 hp Peripheral port road racing engine.

What would you use for hydrocarbon and engine coolant?

Generally, Silicone does not have great properties resisting hydrocarbons. Viton is considered to be better. But then again if the teflon is doing all the sealing, and the silicone is never exposed to the process materials, silicone may have better resistance to setting.

Friction shouldn't be the issue, as this is a static seal.

Dave

No, I don't remember reading anything specific about stock oil control rings not working with synth oil. I have read everything I could about dino oil and synth etc. in rotary engines. As far as I know it is still an unanswered (Mazda) question when it comes to synth oil. I weighted it all out and came to decision based on all I had read as a whole. In my mind there are two possible reasons not to run synth, and I know this has been beat to death. How synth burns in the combustion chamber and the only other thing synth could possible effect - the seals in the engine. I did two things for my rebuild, modified it to inject two stroke oil (I don't premix) and switched to Viton oil control seals. I will lay to rest the effects of these changes after so many miles, provided nothing else fails before it starts to burn oil on start up.
I really only run synth because of the turbo’s anyways no other reason.

Viton is the best choice for exposure to oil and gasoline.

Another bad thing about teflon encapsulated o-rings: they do not stretch for installation. They are only really good for face seals (Our rotor housings are face seals.) Teflon encapsulated seals are too stiff to be stretched out to go over an oil control ring, and then they won't elastically retract back into the groove. Bad choice of seal material for center of rotor oil control rings.