High comp Rew semi p NA
Joined: Mar 2001
Posts: 31,833
Likes: 3,232
From: https://www2.mazda.com/en/100th/
3mm carbons would be better for high rpm than 2mm steels. The reason i say 3 mm for carbon seals strictly, is that they will wear less quickly than 2mm carbons. The only reason to go with carbon seals is they are cheap, will work in n/a's, and are light enough and soft enough for high rpm use. Ceramics are better in basically every aspect though, except that if they break they wreak carnage on engines. Steel seals will be more durable than carbon,, but don't tolerate as high rpms as the other two without causing wear on the housings. When it comes to picking seals, you can't have everything 
Old [Sch|F]ool
Joined: May 2001
Posts: 12,856
Likes: 568
From: Cleveland, Ohio, USA
I wind the wee out of my engines on 2mm Atkins seals and they last a good long while. At least, the apex seals aren't the engine's main wear item, and the rotor housings always look okay. Revs are limited more by the rotating assembly than anything else. I clearanced everything but I still am leery about holding it up by 10k, you know? 9500 is just fine though.
3mm carbon-aluminum may be better than 2mm iron but good enough is good enough sometimes. I wonder which seal would show lower friction. Supposedly ceramics are worth a good amount of power just in reduced friction.
One nice thing about the carbons is that they're one piece. With two piece seals, you either have to worry about a small corner piece falling into a bridge eyebrow, or if you have the aftermarket style long corner piece, then you have to worry about a huge exhaust (or intake
) port leaving the long piece poorly supported.
3mm carbon-aluminum may be better than 2mm iron but good enough is good enough sometimes. I wonder which seal would show lower friction. Supposedly ceramics are worth a good amount of power just in reduced friction.
One nice thing about the carbons is that they're one piece. With two piece seals, you either have to worry about a small corner piece falling into a bridge eyebrow, or if you have the aftermarket style long corner piece, then you have to worry about a huge exhaust (or intake
) port leaving the long piece poorly supported.
So now there's two guys here saying 3mm "might" b better than 2mm on a high rpm na? is there someone here that tried a 3mm carbon for high rpm na? Before I get my renesis rotors cut I want to make sure it's gonna work can't really afford mistakes.
I wind the wee out of my engines on 2mm Atkins seals and they last a good long while. At least, the apex seals aren't the engine's main wear item, and the rotor housings always look okay. Revs are limited more by the rotating assembly than anything else. I clearanced everything but I still am leery about holding it up by 10k, you know? 9500 is just fine though.
3mm carbon-aluminum may be better than 2mm iron but good enough is good enough sometimes. I wonder which seal would show lower friction. Supposedly ceramics are worth a good amount of power just in reduced friction.
One nice thing about the carbons is that they're one piece. With two piece seals, you either have to worry about a small corner piece falling into a bridge eyebrow, or if you have the aftermarket style long corner piece, then you have to worry about a huge exhaust (or intake ) port leaving the long piece poorly supported.
3mm carbon-aluminum may be better than 2mm iron but good enough is good enough sometimes. I wonder which seal would show lower friction. Supposedly ceramics are worth a good amount of power just in reduced friction.
One nice thing about the carbons is that they're one piece. With two piece seals, you either have to worry about a small corner piece falling into a bridge eyebrow, or if you have the aftermarket style long corner piece, then you have to worry about a huge exhaust (or intake
) port leaving the long piece poorly supported.
Joined: Mar 2001
Posts: 31,833
Likes: 3,232
From: https://www2.mazda.com/en/100th/
every competition engine from the mid 1970's to the 13J-M had 3mm carbons in them, they are pretty proven. a 2mm seal should seal slightly better, but wear slightly faster.
The carbons are ideal for revving the **** out the engine, and are relatively cost effective. The 3mm vs. 2mm is only really gonna affect the life expectancy. If you're goin carbon, go 3mm all day long
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