Use Mazda apex seals!!!
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From: Houston
Use Mazda apex seals!!!
I have always been a believer that when rebuilding a rotary engine, you should only use Mazda apex seals. Of course if you can afford them, use the Ianetti Ceramics. They are only $1600 a set!!! Many 13B people use aftermarket seals such as Atkins, Hurley, Rotary Aviation, etc rather than Mazda seals due to price. Typically the difference is around $200 a set for aftermarkets vs around $400 a set for Mazda seals. I have heard good stories and bad stories for each seal. Some seals are so strong that you can't break them. Sounds good doesn't it? You'll just break something else in your engine which will still require a complete teardown and those extra hard seals are murder on your housings when they do work good. But they won't break! Why does that make sense to some people? We are at the point now where we are going to start seeing more and more aftermarket seals appear for the Renesis. It's only a matter of time. Someone always has the latest and greatest seal that can live through even the most careless tuning sessions. Do you really know how well your seals are made?
I've seen stock Mazda seals live on a 13B under 26 psi plus a 75 shot of nitrous to give 620 rwhp. That's tuning right there. I've seen stock seals blow up at 300 rwhp. That's bad tuning. What seems to be the issue? Is it the seal strength? Nope! I've seen aftermarket seals with both scenarios as well. Is it worth saving $200 over? Some people will contend that if it is going to blow up anyways, they may as well spend as little as possible. I contend that if you do everything properly you won't have to worry about it and a good seal will give you years of trouble free service. That is one thing I have yet to see in an aftermarket seal. No one seems to get that far. You can place blame wherever you want it but you need to be shown some actual proof that you should just trust Mazda when it comes to your seals. Here's why.
The first picture is a shot of 2 apex seals. Admittedly the one on the left is a 2mm seal and the one on the right is a 3mm seal. The one on the left is aftermarket and the one on the right is Mazda. See a quality difference? Which one is rougher? Which one do you want rubbing against your housings? It's not to say that all aftermarkets are this rough but all Mazda seals are this smooth. Do you think you should really risk it? These photos are courtesy of rotaryeng.net. I need to give credit where it is due.
http://www.rotaryeng.net/good1.JPG
Do you want to see a graphical representation of how important a smooth finish on an apex seal is?
http://www.rotaryeng.net/smooth.jpg
Here is a picture of an engine that had the above rough aftermarket seals. This engine ran for 3 hours on a dyno. The rotor housings were well within spec at the beginning of the test so no they weren't brand new. Either way, they aren't in spec now.
http://www.rotaryeng.net/Damaged-rotor-house.jpg
This is a housing that was in a well taken care of engine. It had over 150,000 miles of road use and then went into an airplane where it had about 165 hours of use. Keep in mind that the engine is usually at full throttle and at about 6000 rpm in an airplane. I personally rebuilt a 13B at 103,000 miles that looked practically new inside. I kept the original parts, ported it, and put it back together. Even the same seals. It is still in my RX-7 4 years after the rebuild.
http://www.rotaryeng.net/Perry-rotor-house.jpg
It's amazing what a little seal can do. Now, was the $200 savings worth it?
I've seen stock Mazda seals live on a 13B under 26 psi plus a 75 shot of nitrous to give 620 rwhp. That's tuning right there. I've seen stock seals blow up at 300 rwhp. That's bad tuning. What seems to be the issue? Is it the seal strength? Nope! I've seen aftermarket seals with both scenarios as well. Is it worth saving $200 over? Some people will contend that if it is going to blow up anyways, they may as well spend as little as possible. I contend that if you do everything properly you won't have to worry about it and a good seal will give you years of trouble free service. That is one thing I have yet to see in an aftermarket seal. No one seems to get that far. You can place blame wherever you want it but you need to be shown some actual proof that you should just trust Mazda when it comes to your seals. Here's why.
The first picture is a shot of 2 apex seals. Admittedly the one on the left is a 2mm seal and the one on the right is a 3mm seal. The one on the left is aftermarket and the one on the right is Mazda. See a quality difference? Which one is rougher? Which one do you want rubbing against your housings? It's not to say that all aftermarkets are this rough but all Mazda seals are this smooth. Do you think you should really risk it? These photos are courtesy of rotaryeng.net. I need to give credit where it is due.
http://www.rotaryeng.net/good1.JPG
Do you want to see a graphical representation of how important a smooth finish on an apex seal is?
http://www.rotaryeng.net/smooth.jpg
Here is a picture of an engine that had the above rough aftermarket seals. This engine ran for 3 hours on a dyno. The rotor housings were well within spec at the beginning of the test so no they weren't brand new. Either way, they aren't in spec now.
http://www.rotaryeng.net/Damaged-rotor-house.jpg
This is a housing that was in a well taken care of engine. It had over 150,000 miles of road use and then went into an airplane where it had about 165 hours of use. Keep in mind that the engine is usually at full throttle and at about 6000 rpm in an airplane. I personally rebuilt a 13B at 103,000 miles that looked practically new inside. I kept the original parts, ported it, and put it back together. Even the same seals. It is still in my RX-7 4 years after the rebuild.
http://www.rotaryeng.net/Perry-rotor-house.jpg
It's amazing what a little seal can do. Now, was the $200 savings worth it?
Last edited by rotarygod; Oct 9, 2006 at 10:09 PM.
Shifty Bastard.
Joined: Feb 2004
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From: Melbourne, Australia.
Originally Posted by rotarygod
I fixed that while you were posting.
That last pic is amazing. I have a 12B in bits in the garage that has done less miles than that.....the housings are shagged in comparison.
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From: Houston
My own 13B blew me away when I opened it up at 103,000 miles. It looked like my 30,000 mile Turbo II engine. Both engines were very well taken care of. I have no doubt mine could easily go another 100,000 miles with room to spare if it is still well taken care of. Mine had zero signs of chrome flaking anywhere. Not even on the edges.
Shifty Bastard.
Joined: Feb 2004
Posts: 4,835
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From: Melbourne, Australia.
Originally Posted by 8 Maniac
great post... starting to think the tech garage might need a sticky of all RG's threads like this lol
I wanna rock! Rock!
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From: Monterey, CA
I'm going to go out on a limb here..
Here's a list of things that I suppose will keep a stock engine in good condition:
1) change the oil often and keep the level up
2) keep the cooling system in good condition and change the coolant yearly
3) make use of the upper rev range regularly
and for modified engines:
1) make sure the air/fuel ratio and timing are set right to help prevent detonation
2) increase cooling capacity
Is it that simple or are there other, more specific things we should be looking at?
Here's a list of things that I suppose will keep a stock engine in good condition:
1) change the oil often and keep the level up
2) keep the cooling system in good condition and change the coolant yearly
3) make use of the upper rev range regularly
and for modified engines:
1) make sure the air/fuel ratio and timing are set right to help prevent detonation
2) increase cooling capacity
Is it that simple or are there other, more specific things we should be looking at?
Great post RG ! You 
Hmm ..... those cermaic Apex seals are quite expensive .... Im sure they're good (better be good!) but thats like what 1/2 the price of the engine itself ? .....
Use good engine oil ? Synthetic. 
Hmm ..... those cermaic Apex seals are quite expensive .... Im sure they're good (better be good!) but thats like what 1/2 the price of the engine itself ? .....
Originally Posted by mikeschaefer
I'm going to go out on a limb here..
Here's a list of things that I suppose will keep a stock engine in good condition:
1) change the oil often and keep the level up
2) keep the cooling system in good condition and change the coolant yearly
3) make use of the upper rev range regularly
and for modified engines:
1) make sure the air/fuel ratio and timing are set right to help prevent detonation
2) increase cooling capacity
Is it that simple or are there other, more specific things we should be looking at?
Here's a list of things that I suppose will keep a stock engine in good condition:
1) change the oil often and keep the level up
2) keep the cooling system in good condition and change the coolant yearly
3) make use of the upper rev range regularly
and for modified engines:
1) make sure the air/fuel ratio and timing are set right to help prevent detonation
2) increase cooling capacity
Is it that simple or are there other, more specific things we should be looking at?
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Joined: Dec 2014
Posts: 235
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From: New England
MAJOR THREAD REVIVAL!!!
Glad i went OEM Seals, my builder who is used to 7s have no faith in them but with 2 new housings, the only option for me was to keep it OEM all the way!
How well have these builds held up over the years RG?
Glad i went OEM Seals, my builder who is used to 7s have no faith in them but with 2 new housings, the only option for me was to keep it OEM all the way!
How well have these builds held up over the years RG?
To be clear, you are listening to the advice of someone who...
A. never owned a RX-8
B. recommended the Hymee supercharger
kthxbye
A. never owned a RX-8
B. recommended the Hymee supercharger
kthxbye
Oh and I concur on using OEM seals. But what seals you use doesn't mean **** if your builder sucks and uses other out of spec parts.
Last edited by 9krpmrx8; Jul 19, 2016 at 12:37 AM.
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