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Chronos 11-26-02 09:16 PM

Ceramic Apex seals and high reving engines
 
My 3rd gen is in need of a rebuild and I've been doing a lot of research on ceramic seals...One of the characteristics I noticed about them is that they have less friction against the housing than stock seals. However, I also read they are designed for racing and you really don't see performance gains below their optimum range of 6k-10k rpm. This led me to wonder what I would need to have an engine run at these levels and if It would really help me in road racing (I'm not very big on drag). Does anyone know much about high reving rotories? Would they gain more power from the extra 2-2.5k of rpm or would it just make it easier to road race since I would constantly be under full boost.
I plan to eventually be running a GT35/40 or T04-R but as of now I'm on stock twins.

P.S. I know ofcourse that the ceramics are more resistant to detonation...I'm wondering about their performance gains

diabolical1 11-26-02 09:40 PM

Re: Ceramic Apex seals and high reving engines
 

Originally posted by Chronos
Does anyone know much about high reving rotories? Would they gain more power from the extra 2-2.5k of rpm or would it just make it easier to road race since I would constantly be under full boost.
well, i'm not a Gen III guy, but with this part of your question, it's important to know if this car is driven on the street regualrly. if it is, then i don't know if you'll want to make the mods necessary to create a motor that lives between 6 and 10 thousand RPM. you're talking an "almost-unstreetable streetport" or a half-bridge at the very least!

if your concerns are centered around possible detonation, then my best advice would be to build the motor with the street seals, and just make provisions for fuel and ignition to tune it correctly ... in other words, with enough fuel and spark to keep it happy under load, in the upper RPM ranges and under boost.

Carlos Iglesias 11-26-02 10:45 PM

Ceramics aren't about (direct) performance gains, they're about increased reliability.

Increased reliability from increase resistance to the damage detonation. Increased reliability from reduced wear. Increase reliability from reduced rotor chatter (at higher rpms.) And most importantly, increased reliability from the mechanical paranoia of ever having to pay for another set! ;-)

This from a guy who has had ceramic seals since '97 when they still came with x-rays charts to validate their structural intergrity.

Flyin, Racin, and Buildin Rotary Beasts,
Carlos A. Iglesias
'93 RX-7 R-1 (Racin')
'95 M3 Sport (Drivin')
'01 Pathfinder SE (Towin')
http://www.the-rotary.net

Chronos 11-27-02 06:45 AM

yep, I've seen the pictures ;) (nice case they come in too!) Ceramic seals are indeed good for that purpose, but in Jimlab's case, bad tuning is bad tuning, and although they resisted about 3x as long, they still went, just the same as stock seals...So although I recognize and appreciate the fact that they do hold up MUCH better...I'm just gonna take every precaution to tune correctly, I'm sure it's possible. Your statement about increased realibility for reduced rotor chatter coincides with what I'm looking for, better performance at high rpm with the ceramics, which now I come to the conclusion can only be reached by extreme porting, which I don't want, so I think I've made up my mind on the matter :)


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