how does it affect power? lifespan? which type of seals are better for this? what exactly is thermal expansion?





discuss

thermal expansion as in how metal expands and contracts with changes in temps? it seems like that could be a big problem.

how is this different for :



mazda seals

iianetti eramic

rotary aviation

I dont think it's much of an issue, that's what the seal spring and internal lubrication is for?

This is why clearances are adjusted for different apex seal materials...





-Ted

Mazda stock seals and RA seals will be very similar in there expansion properties, while the ceramics will change very little in comparison.

The seals are so thin that the change in expansion, even from exhaust gasses, are factored into the machined tolerance in the seal cavity I would think.They should expand around .0015” at a temperature increase of 2000 F*, which is higher than EGTs should be normally. Seal clearance is around .002-.004 so there is a little play there.



I was recently told that you can get up to 30% more torque (in certain RPM ranges of course) from ceramic seals because of lower coefficient of friction values.



But I really believe from reading a lot on the subject that the cost of ceramics far outweighs the benefits for any practical application.



And with the resent foul up of RA I will wait to see how their seals pan out over the long run.



has anyone hardness tested the RA seals against mazda seals yet?

What's this, I have not heard about this?

The hardness of a mazda 3 piece seal that I have (used) is about 1100 Hv (Vikers microhardness) with a 500N load at the seal edge and around 600 Hv with the same load at the beveled edge

What would be a good *end* clearance for one piece iron seals?



This is information that I can't find anywhere.