fdbabb

Regarding the large inner coolant O-ring seals that lie in the side housings of the 93+ 13b tts, the ones that define the border between the water jacket and the combustion chamber. Usually Teflon or some hard material guarding the orange rubber or silicon interior;

1.)When the engine is clamped together by the 18 tension bolts, isn't there still enough space for combustion gasses to go outward that 1/8 inch and come in contact with a very narrow section of the seal??..

2) If so, wouldn't a small strip about .003 inch thick and 18 inches long or so, just along the rotor's arc from a little before combustion to well past the exhaust on the inside of the groove go a long way to shield 1400-1600 degree gasses from eventually degrading the ring, if not acting as a heatsink.

3.) At SevenStock 7, I saw a vendor out of Canada selling O-rings completely enclosed with some sort of hi temp material with the orange material sealed up within. Was this also teflon w/silicon?
Anybody remember their name?

Thanks,
Jeff

RETed

When the engine is torqued properly, it will crush the metal shield down.

Unless the housings are warped or debris gets caught in between the housings, the seam should prevent most combustion from hitting the water jack o-ring.

It's not just temperature that you should be worried about.
Typical combustion pressures are over 1,000psi.
Detonation can easily cause pressures to spike over 10,000psi.
You think that seam and any o-ring can hold up under those conditions?

Yes, it sounds like it's the "TefSil", telfon encapsulated silicone o-rings.
They are available from McMaster-Carr for $10USD each.


-Ted

fdbabb

<quote>"should prevent most combustion from hitting the water jack o-ring.

It's not just temperature that you should be worried about.
Typical combustion pressures are over 1,000psi.
Detonation can easily cause pressures to spike over 10,000psi.
You think that seam and any o-ring can hold up under those conditions?</quote>

Well, you just made my point...

I _don't_ think it can hold up over time (that's the whole purpose of this post).

It doesn't really matter that "most combustion" isn't hitting the O-ring...
where ever it _IS_ hitting is going to experience degradation over time. I want to shield the seal with some sort of metal strip in the groove facing the combustion gasses.

The problem with my idea about a long thin strip is that, even if it wasn't wide enuf to undergo crushing, the edge of it resting on the rotor housing wouldn't be a perfect enuf match to prevent hot gasses from getting by it & hitting the seal. And that is what 'm trying to prevent in the 1st place.

The TefSil McMaster Carr stuff is what got put in last time it was rebuilt. What I want to know is ... Is that the best there is? (I thot the Canadian outfit I talked to at 7stock7 was onto something. ) Any room for improvement? Any cool tricks the racers use?

j9fd3s

iTrader: (3)

they used to have a little shield for the water seals, but its long dicontinued. i think you'll find the root cause of bad water seals are the fd turbos. in the rest of the rotary world the water seals will last until everything else is worn out