Rip

I have a question concerning the material used in the ceramic apex seals is it the same material used in ceramic lifters?

ceramic lifters are made by:
schubeck racing

I was under the impression that ceramics should have such a low friction that wear is nearly elliminated. But from my experience from the RX7 club forums this was not true. And I wanted some information concerning the matter now that I own a RX8.

Also if this material lived up to the hype are there ceramic bearings?

Thank you for the help
Rip

StealthTL

iTrader: (1)

The actual formulation of that ceramic is a closely held trade secret.

S

rotarygod

Ceramics do have a lower friction coefficient than the stock apex seals. Whoever said otherwise on the 7 forum is wrong. Then again I'd argue that about most over there! The springs used with ceramic seals are actually stiffer for this reason. They can be without suffering the wear penalties of a higher spring rate.

I don't know of any ceramic bearings for the rotary. To me the term bearing is a bit strange since babit style bearings don't actually touch. The "bearings" are really nothing more than a way for oil to be used as your bearing as it is being held and applied to one area. Since bearings never touch (hopefully!), I argue that they can never truly "break in" as people think they do. This is backed up by the fact that the thin opaque film that bearings come with when new is typically still there when an engine is disassembled. This film can be wiped off with a soft tissue. Any contact would be far more abrasive. Of course I'm getting into another topic altogether with this.

Rip

I'm sorry for the confusion, yes they did say that they would lower friction, but it has been my experience with these ceramic lifters that wear is nearly elliminated. In other words I'm asking whether or not the apex seals or the housing would ever need to replace replaced due to wear?

And yes bearings operate such that the crank (or what have you) rides on a thin film of oil not the bearing. Rather the bearing is suppose to route the oil to produce the correct clearance for the oil film. So are you saying that the rotary engines will not show bearing wear? I was not sure if this was as much an issue due to the rotary's smooth rev's. But it has been my experience that all motors wear. I assume that the facilities that balance the crank is very good, but even at start up the motor will not always have sufficient oil. When one rebuilds a rotary, is it necesary to grind the crank or use over sized bearings?

Thanks
Rip

rotarygod

As long as you didn't blow the engine up from detonation or overheat it, an engine with ceramic seals should have lower wear and last longer. Keep in mind that we only have ceramic apex seals available. We still use steel side and corner seals so wear still takes place in other areas at the same rate. The rotor housings themselves "should" last much longer with ceramic seals.

No we don't "grind" the eccentric shaft or use oversized bearings. It's not to say they can't get out of spec. There is always some form of wear taking place. Even from the oil itself as weird as that sounds. Just think of water over rocks over millions of years and you'll get the picture. Small contaminants in old oil contribute to this also. The wear that takes place isn't due to bearings actually touching. They should never touch.

Rip

thank you for the clarification

Rip

diabolical1

well, from what i understand, there are some ceramic corner seals in the works for the older 13Bs. i would imagine the Renesis will have seals, too, at some point.

re-rx7

Ceramic seals are lighter however. Mostly used in racing applications. People tend to think these things are indestructible. Save the money and spend it on tuning. Mazda did their research on the rotary's.