What seals will be better for a bridgeport 12A

Thanks

 

Steel are for 8.500 RPM and lower. With a BP your powerband must be higher than 8.500 RPM? If so you can't use steel. Carbon is good for 8.000 RPM and higher, but don't last that long. Think about 20.000 Miles.

 

You're from Christchurch, SeriesV? How did you post 17 times without me noticing that?

Aico is right. Here's the quote from the Mazdatrix website:

"Note: The carbon apex seals are designed for racing only. They seal better above 8k rpm due to their lighter weight. They do NOT last very long (20k miles on the high side), and do NOT seal well at low rpm's (like starting and at idle). Not recommended for turbo, supercharged, or nitrous engines."

http://www.mazdatrix.com/b3.htm

That's not really conclusive, but the poor sealing at low RPMs with the carbon ones sounds annoying. I guess others will be able to give a more experienced answer.

Bye,
ScruffyChimp

 

so if steel is not good above 8.5k and carbon are not good below 8k, what the hell are you supposed to use on a bridgeport? stock apex seals?

 

carbon-aluminum is not so good below 4k, due to them being of one piece construction. 2 piece seals seal better because the length is self-adjusting, however they don't make carbon-aluminum 2pc seals.

the life of a carbon-aluminum seal is in inverse proportion to how high you rev the engine and how often you are up there. (super insane 5-digit race engines will only get about 6 racing hours between rebuilds )

If you plan on ever exceeding 8500 even for a few seconds, get carbon-aluminum. If you plan on a full bridge (all four ports bridged) and you want to relieve the rotor housings, you need 1-piece seals, which generally means carbon-aluminum.

 

Yeah or ceramic. But at what $1200 a rotor I'll pass on cermaic...

Another major benefit of carbon you guys didnt mention is when you greande a motor. The carbon seals dont destroy your rotor ot rotorhousing... So its a tradeoff..

 

Only if the apex seal springs don't find their way out too!

 

What about a half bridge? Is the powerband low enough that you could use steel apex seals and still have a good engine lifespan? How much power could you expect from a halfbridge with a good induction and exhaust system anyway?

 

I plan on finding that out for myself

 

This is the case for me. FULL bridge, rotor housing matched, carbon seals are a must! If you are planning spending ALOT Of time in town idling through town, which is 2000rpm, you shouldn't be making one. If you can get out of traffic easily(SPEND AS LITTLE TIME IN TRAFFIC AS POSSIBLE, FULL bridge it is!! Half bridge isn't really worth it. Full bridge is great! Believe me!

As for hard starting, its not really hard at all. IT smells ALOT more raw(race car smelling) out the tail pile at idle, but this is what happens when you have excessive overlap and seals designed for higher rpm. As for sealing, if you just keep the engine above 3 to 4K, in part throttle conditions, you will be more then fine, afterall its a rotary, these can rev and beg to.

 

how do the steel ones seal at low RPMs. I will be doing a large streetport on my engine(daily driver or it would be a bridge). I want something that will let me spin it up to about 8k.

 

steel ones are fine/best choice for street ports. Your power peak will not go past 8500rpm with a big street port.

Steel ones seal best at lower rpm range. idle-6200rpm. After 6200, they will start to chatter and chatter worse higher you go.