That’s what I suspected from all the posts I’ve read, just wanted to verify.

 

dont the ceramic seals, not seal well in the lower rpm band?

 

I'm surprised I haven't already posted in this thread about my own opinion

In general, I recommend (and we use) OEM 2mm seals in the majority of builds. I've built a few engines with ceramic seals at the specific requests of customers, but we don't recommend them.

I'm interested in the ALS seals and they seem promising given the limited data available right now.

RA seals, I'm on the fence and leaning towards a thumbs down. On my personal engine with approx 4-5k miles on it, the vacuum continues to worsen with a negative trend. I need to check the compression soon to get real results. The engine has withstood three road race track days and lots of hard running on the street, with boost levels as high as 22 psi on pump gas with water injection. On the one hand the car has been bulletproof, on the other hand I worry a bit about my brand new rotor housings

Btw, I have been premixing a fair amount..... *with* a working OMP, I'm using approx 1/2 an oz per gallon of fuel.

 

ceramic seals are one piece and cause less torque due to blowby past the seal and hard starting issues, once started they are a good racing application seal which cause literally almost no wear but can break if a large detonation occurs.

pettit also sells "used but good" ceramic seals for half the price of a new set at around $600 for a used set of 6.

i have however rebuilt one of their racing engines from their old FD track car that had tossed a ceramic, it took out everything including the irons. they are good seals but still susceptible to failure even at ~350WHP.

the atkins seals are actually weaker than the OEM seals when detonation is applied to them, i have experienced several failures but the softer maerial does cause less damage when a failure does occur as they most likely will chip the sharp corner of the seal and eject it right out the exhaust port versus the stock seals basically "shattering" into many small pieces which can cause extreme damage as well.

 

GoodfellaFD3S, are you running the RA super seals or classics

 

I've heard the same thing.... Atkins are similar to the old Hurley seals. Break easily, but cause little no damage. I've been through that before, no thanks.

The RA Black/'super' seals.

 

well i should say that they are weaker than the OEM 3 piece seals, which had the shattering effect, the new OEM 2 piece seals are very similar to the atkins seals and only break off a corner of the seal which results in less damage. it only took mazda until well after production to fix this mistake.

 

Anyone running the RA classics, It seems that they are weaker then the Supers inturn on the housings, but what about detonation?

 

Stay away from RA classics, last time I took my motor down they had galled the housings and I had to re-arc the springs as they were flattened below Mazda spec. If I had had money at the time I would have replaced them. They were also very slightly warped If I remember correctly. the car still drives fine but I know the housing are being slowly converted to trash. I've been running high moly oils since I discovered the damage to try and help it out. (or to make myself feel better ...)

Most of the aftermarket seals are just soft steel, that's why they don't break but bend. They lack the low friction characteristics of the stock hardened cast iron seals and thus eat the housings. This can be backed up by JHB who does housing re-chroming and does not recommend chrome housings with ferrous seals below 60 Rc hardness.

Another issue is ANY two piece seal which has a large tip piece is worthless and the seal manufacturer has absolutely no engineering sense. Large tip piece 2 piece seals are effectively one piece apex seals as far as sealing is concerned.

My recommendation and the rule I will follow from now on is ONLY stock Mazda unless you have the money for ceramics.


I'm going to be saving up for some NRS's just to have for my next rebuild. They actually look like a great deal and seem to be engineered correctly


I'm attaching two files, the first is an example of why large corner pieces apex seals are junk and you should instantly dismiss any company who makes them. Blowby is in red, housing is in blue. A one piece apex seal would have blowby along the side where it is clearance slightly smaller than the housing.

That's another thing any 2 piece apex seal that is clearanced below the rotor housing width is also junk (even worse junk) as it would blow by along the whole face of the large apex seal piece.


Second attachment is a housing after RA seals, It's not mine but shows pretty much exactly what mine looked like. Mine were mint 60k housing before the RA seals and looked like this after like 10k miles.

 

my first motor i used ra classic seals,and after 3k miles i had chatter marks from hell in my housings

then i used atkins seals,and they broke and caused a bad rotor/housing

now im running 3mm oem seals. well see how it goes.lol

trying to get a little experience will them all.

 

So I thought I would be the lone Atkins post. I have be running atkins 2 piece 2mm since 2002. I had about 98K when I did my swap and I have 142,789 now so I have 44,789 on them. I ran a Camden supercharger for years at 8-10 psi (only made 220 rwhp with 70 shot so not really pushing them).
https://www.rx7club.com/attachment.p...3&d=1215962616

I locked up the supercharger with a 100 shot and the engine was still good. Put on a turbo and have been running 15 psi for 2 years (guessing 300 rwhp). It's still running.

Overall I have been happy, but I think I am slowly losing compression do to seal wear. If I do a rebuild I'll go OEM 2 piece or Atkins again depending on budget.

I have hear clearancing the ceramics is a nightmare.

 

Hi guy's,

what are your thoughts on the mt seals? (Metal Technology apex seals).
here is one of there vendors http://www.skernracing.com/apex

 

I wouldn't go that far..... it certainly takes more time and is more involved, but nothing that a good builder won't be able to handle.

 

I have not used them myself but I watched a friend struggle. I think he had to buy special tools to file them to size, which as you said takes more time.

Would you agree the average Joe who builds a 13b might not be able to do the job? I definitely would not recommend them for a first time builder.

 

I just built my new engine with these seals and so far everything seems fine. Vac is fine should be finished breakin next week and tuning begins. I will see in the long run how the seals work, I have heard good things abouth them.
If anyone else is using them please chime in.

 

i run 1 oz per gallon is that too much?

Does anyone know if you can get ALS seals for a 12a?

 

i got my apex seals, in fact everything needed to rebuild my engine(bout 7 yrs ago), from a local race builder(roger mandeville). i'm pretty sure they were all oem replacement parts.

 

super seals all the way

 

ive heard awesome stuff about RA seals..... However ive heard they are almost too hard. Is everyone that uses them experiencing housing destruction by these seals?

 

super seals suck.....may be good 4 racing .no good for day to day...oem.. oem.. oem

 

2-piece OEM in mine. great compression on my re-used 180,xxx housings... So far.

 

This information is really useful. What about the Metal Technology Apex Seals? I have a friend who uses them in his 690+hp Fd every day driver. 35lbs of boost. They have been in his car for over 2 years. Check out their website
http://rxparts.com/

 

I'm running RA 3mm super seals with approximately 5-6k on the motor so far. It took 23 psi on pump gas + water/meth injection all summer and vacuum has not changed whatsoever. Only time will tell how the motor holds up though. Oh, and I also premix ~ 6 oz to a tank, and I'm using the stock OMP. However, I as well worry about my brand new rotor housings sometimes from what I've read about these seals...

Lastly, prior to this motor I was running the Atkins seals (already in the motor when I purchased the car). At ~370RWHP the car puked 2 seals out of the rear housing, taking out the rotor housing and my secondary turbo (was still twin turbo'd at the time). FWIW, I was running around 15 psi of boost when that happened, and this was prior to running water/meth injection.

 

super seals again and again

 

What will the rotor housings look like after 60,000 miles or more?



~20k on non-Mazda seals, 1-2oz/gallon premix used. Housings were smooth before these seals installed. 8k redline max (no more than ~5k sustained for more than a few seconds) with one or two peaks above that.

Engine has ~40k on it now, and has extremely low compression. Combination of poor air filtration and high RPM probably did it in. Haven't taken it apart yet.

For a drag engine that sees maybe 200 miles per year, housing life isn't an issue. For a street engine, well... I drive my RX-7 about 30k per year. Assuming that I can keep an engine in it, which this year has been a massive issue.