mrgnex

When rebuilding an engine one component seems to be the most controversial. The famous apex seal.
Unlike any other seal there are countless manufacturers and versions and of course they all believe they made an indestructible and non-wearing seal.
From what I have seen the Mazda OEM seals are the most recommended and they are what I'll be using for my rebuild.
The RX8 is different from the RX7 due to the higher RPM and lack of boost. The compression is higher though. Some companies like REC (rotartyengine.com) offer a service to fit the longer RX7 seals into the RX8 rotor using an EDM process.
I have searched around and found the following seals:

1. Stock ($360)
   
2. Goopy performance seals ($295)
   
3. REC (rotaryengine.com) treated seals ($435.50)
   
4. I-Rotary seals ($595)
   
5. Atkins Rotary seals ($199) (Or this? ($250)) or Cryogenically treated ($249) (Or this? ($300))
   
6. Atkins black satin seals ($250)
   
7. Ianetti ceramic seals ($2327.50)
   
8. E&J apex seals ($400)
   
9. Rotormaster competition (ceramic) seals ($800)
   

I would love to hear your opinions about the seals or if going with some specific RX7 seals would be worth the hassle. If I missed any please let me know!

TeamRX8

iTrader: (25)

RX-7 depth is best and for NA use; Iannetti ceramic are the best and easiest on the housing surface long term, but most costly as you see. Mazda OE is probably your next best option imo. Some/most of those are intended for turbo use and you’re not likely to need detonation protection and the harder material that in turn is harder on the rotor housing surface generally speaking. The other Iannetti seal is metallic based and designed for high pressure turbo use and they claim better surface wear than those others, but then recommend fairly high pre-mix/oil injection rate for them. The Iannetti ceramic are not tolerant of detonation, which is why they’re great for NA, but most people avoid them for turbo because a blown engine is bad enough without eating up expensive seals. They have a more expensive ceramic set than that too; the Iannetti “Gold” version. Appropriately named if you saw the cost, lol. Be advised that not all “ceramic” seals are created equal. I really don’t trust most of those claimed to be as much as the Iannetti brand.
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Pettit can also provide the machined RX8 rotors. They claim to have an improved Mazda OE seal that is not sold to the public, but whether they’ll sell them along with the modified rotors separate of a built engine is something you’d have to ask. That info is on their engine website page.

The way I explain the apex seal depth difference is this. The RX7 seals are about twice as deep as the RX8 seals. So dig two holes; one twice as deep as the other and put a fence post in each so they stick out of the ground at the same height. Fill the dirt back in around both equally packed. Then start pulling back and for on each post, which is what happens to an apex seal in general use. Eventually the shallower post will start wallowing out the the hole it’s in sooner than the deeper one that has more material around and supporting it against the force. In addition to this, the shallower seal is more prone to bowing/warping than the deeper seal when subjected to high temperature over time. IMO it was a bit of a mistake by Mazda to have done that and it contributes to wear and rebuild expense on the Renesis engine. It’s why I generally don’t recommend reusing standard RX8 rotors for a rebuild. The RX7 depth rotors can usually be reused multiple times, but obviously that could depend on other factors
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mrgnex

Thanky you for your input! I do agree that the RX7 seals are preferred, I think Mazda chose shallower seals because they are lighter and would allow higher rpm applications. Using an EDM process to allow the 2.7 mm deeper RX7 seals to be used might be a worthwhile investment.
I am aware of the fact that a ceramic seal would be the optimal N/A choice. The price however is significantly higher and might not be worth it.
To me using any other ceramic seal other than Ianetti is out of the question. Ceramic seals do not change dimension when heated up so if they used the standard apex seal tolerances to produce ceramic seals a lot of blow by would be present resulting in low compression. I have not seen any data on the manufacturing process and data backing up their claim that the ceramic seal is produced and performing right.

What RX7 seal would you recommend? Using the Mazda OEM one?

TeamRX8

iTrader: (25)

try reading the first several sentences again

also the Pettit paragraph too
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