Rotary Aviation apex seal report
 

I just tore my engine apart which had about 20k miles on it running Rotary aviation apex seals and springs. I was slowly losing compression until it got bad and I took the engine apart. Found some of the apex seal springs flattened, same with some corner seal springs. Also 2 brken corner seals. I did run a little lean in boost sometimes, and expierenced detnation. Which could cause this, so I understood.

When I took a close look at the rotor housings I found chatter grooves running all the way around the rotor housing. They are light but are on the whole housing. They get deeper on the part between the exhaust port and the spark plug holes. I dont know if the apex seals caused this or what. I will post pictures of it tonight.

Who did the rebuild? Did you use the RA springs as well? Tracy admitted that the springs were reliable up to stock boost levels. How much boost were you running? The springs may be the cause of the chatter marks because of them not putting the right amounts of pressure against the apex seals causing them to float. I'm no expert but that sounds logical to me. Also if you broke 2 corner seals that was either some major detenation or your side seal clearence was too tight.

Chatter is usually caused by overheating or lack of lubrication.

I never overheated the engine. Temp was always around 90C according to the wolf3d. Lubrication was fine, I premix about 1 ounce per gallon of gas. When I took the engine apart everything had a film of premix on it so lubrication isnt the problem either.

Did you use the RA springs?

yes, read the first sentence, he used both seals and springs.

how much boost were you running? i'm using both seals and springs too, now i'm kinda wishing i just used mazda stuff...... oh well, it'll take quite a while for me to hit 20k anyway. i'm running 15-16 psi though.

harrison

Here are some pics. I was running 8 psi, but leaning out. I just ordered some new corner springs and mazda apex seal springs.

Do you guys think I can sand this smooth, because I was told by someone it would work. The grooves arent very deep, just not smooth.

You and me both, I think when the funds are available again. My motor will likely be coming apart, and the RA seals/springs will be replaced with Mazda parts.

Agree...
I'm using the RA seals and mazda sprigs. I'm actually at 18 psi T70 no problems... Kaboosky made 520 whp @19 psi with that set-up ... though, neither kaboosky or myself have get 10K so time will tell...

BTW I sanded the housing with 320grit sand paper for about 15min each and they turned out like new. I ordered some new mazda apex seal springs and RA is giving me a new set of seals if I send them this set so they can look at them.

Can you tell me please the difference between RA Apex Seals from Mazda Apex Seals??? I would like to understand better the information I have... :bigthumb:

The Mazda seals are compatible with the housing surface,it appears the RA ones are not.

No thats not it. The RA springs are not heat treated like the Mazda ones. The RA springs are best used in a NA application.

I once had made some apex seals from machine tool steel.These scored the housings like the RA seals have.Because of too much friction,the apex seal would 'weld' itself to the housing surface and tear off a tiny piece of tip,which scored the housing.This left lots of scoring and very little compression,because the seals were incompatible with the housing surface.

You either use Mazda OEM (Ferrous or Carbon) or you use the BEST quality Ceramic Seals (like NRS, that I personaly specify and supply to many shops), everything else in a steel type is a piece of shit and will fuck your housing and rotor slots very quickly or they will distort like plastic as soon as conditions get hard....

Expensive lesson to learn.

Were these new rotor housings? What did RA say when you talked to them (i.e. have they actually changed anything in their seals, or did they just send you another identical set?)

Sounds like it's time to tear apart my brand new motor... :(
-Manolis

This is chatter !!!!

Those housings clearly show apex seal wear on them, which is not a good sign.
They actually remind me of housings which Hurley seals were used on.

I've got RA seals and my housings are all scored up like that too, not chattered but scored. The engine had 8k miles on it and the housings looked almost perfect before I used the seals.

I'll probably use OEM Mazda seals next time.

Yeah thats the same way mine looked as well, and I run 100:1 premix all the time...Something material wise is just not jiving...

the pictures you posted dont seem to appear to have chatter but what id does that is abnormal wear of the housing. somoone mentioned running hot or not enouf premix, (you gauge could be off) constat exposure to heat can cause this especially if you are runing lean this is even more so.
was this by any chance the early batch of the RA seals? i build some engiens with these seals and srpings one of which is a local friend who we dynoed at over 420whp and 16-17 psi of boost and his engine sounds good so far (yes the sound of the engine can tell you a lot)
i have read a lot of the these RA this RA that but to tell you the truth i have yet to read one convincing review that shows the seals or springs at fault.

actually, chatter marks are caused by over revving. the apex seal lifts off the rotor housing and slams back down causing an indentation. rotor housing grooves run perpendicular to chatter marks. over revving also causes flattened apex seal springs.

i have seen those same marks in your picture in stock mazda engines using mazda seals. can you feel an indentation on the housing.

Well obviously these arent chatter marks but apex seal wear on my housing. Its been mentioned many times now. I ran more than enough premix. 1 ounce per gallon of gas, when I took the engine apart everythign had a coat film of premix. I dont see how my housings get that screwed up over a month of driving. Thats right I only drove it with a turbo for a month, and thats when I screwed up the springs and started losing compression.

I totally agree! I only use Mazda seals.I did try some Iannetti one piece seals,they gave not enough compression,no more wheel spinning on throttle.
Chatter marks are across the housing,where the one shown has score marks right around,they are not chatter marks.The springs probably collapsed because the apex seals were way too hot,too much friction.

Yea this sucks i dont know what to do. Maybe I can sell the set of new seals and springs I get from RA for $150 or so and get some mazda seals?

Tim, are you using the old three piece or the newer two piece oem seals in your 1st gen drag car?

I have seen LOTS and I mean lots of back yard manufactured ferrous alternatives to Mazda seals and they are all junk ! They (if they survive) will root rotor housings just like they have done to yours, they are not tested to be compatible with the rotor housing surfaces Mazda manufacture PERIOD, they are prodominantly made to cater for drag racing people who detonate engines every other day and if made (as some are) out of cold drawn mild steel bar !!! YES MILD STEEL BAR !!!! you can bend those fuckers in a vice and they will not break.............. but they are pure shit in so far as durability and wear properties on rotor housings ans rotor slots.

Mazda OEM seals are the only (steel type) seals I have seen that are long term durable on rotor housings, so if cost is an issue I recommend those. If long term costs are what you are looking at then you cannot beat quality ceramic apex seals, they last many times longer and are much kinder on mating parts than even OEM seals. You can get them in multy piece style and match the OEM compression figures, but I prodominantly run one piece style for much increased strength and mechanical design reasons (greater clearances) so the seals are far more tolerant to running 40+psi boost and up to a 400+shot of spray !!! The 2% to 5% loss in compression (due to racing spec end clearances) is not a factor when the seal is 100% reliable.

PLEASE STEER AWAY FROM THESE SHITTY NON MAZDA STEEL SEALS, THEY ARE NOTHING BUT HEAD ACHES AND A PURE WASTE OF MONEY !

very interesting rice!!

what ceramic seals do you like the best?

nrs? never heard of them....
12a seals available?

I only use NRS Ceramic Power Seals, I/and my assosiates have used all other alternatives (from various vendors). I like them that much that I am a sole distributor for them in my part of the world, we sell to lots of shops & race teams with great sucsess ;)

e-mail me

riceracing@ozemail.com.au

I am using the old two piece,it is still a 12A.
The one piece ceramics only gave 5 bar compression,like having a worn out engine.I get 8 bar with the mazda steel ones.I have had the rotor housings 'cermet A' coated,and intend to use the Mazda seals,so will I have a compatibility problem? I shouldn't have,because ceramic seals don't score the housing,but how ceramic is 'cermet A'?

ups

Those rotor housings are gone.

owner said it was sanded down and polished and came out pretty good

you shoudl post the pic of the second housing

We have one piece ceramic producing from 7.9 kg/cm^2 to 8.10kg/cm^2 on a corrected high accuracy gauge. You have some other issues to be only reading 5 bar, faulty set of seals probably ???

Yes you will have a comatability problem, the people who do the Cermet coating infact recommend our NRS seals as a compatable seal, or to use their own manufactured seal.... you better check with them before you buy Mazda OEM seals.

What about contamination? Was the owner running without a air filter down a dirt road pretending to be Bo and Luke Duke?

how did the bearings look in that engine?
any marks on the rotors towards the trailing end near the apex seal groove?

i've seen motors that ate the bearings for one reason or another and the rotor housings came out looking similar to that.

so, other than the score marks and flattened springs, how did the rest of the parts look?

yes , bad bearings can contribute to the premature wear of the housings. the eccentric shaft becomes unlevel and has more room move (vibrate), which also moves the rotors and apex seals.

Bearings were brand new in the engine when I assembled it. When I removed them they looked just as good as when I put them in.

Rest of the parts looked good, just the flattend springs and a couple cracked corner seals.

With the Iannetti one piece seals,problem is I had 0.15mm end clearance as they came,I couldn't make them longer.There was a brown streak on each side plate,where gas had escaped around the end of the seal.Are you saying the NRS seals are better than the Iannetti ones? What end clearance do you have to get 8 bar compression? Maybe I should buy some NRS seals.

The NRS seals come with a 0.14mm (0.0055") end clearance.
3.1455" total length on 13B seals.

Can you actually sand down the surface of the rotor housing? I was told that the housings were specially coated and could not/should not be sanded. :)

You can, just not much. I didnt sand that much to go through the coating, its still on there.

How do you get 8bar readings from a comp test with ceramics? Every car with ceramics that i have seen comp test results has been below 6.5bar. At a rough guess that is 5 cars. Not a lot I agree but wow what great compression. When you put mazda OEM seals in you get 8 bar Nooo prob.
In my FC with second hand 2 peice Mazda tips( and everything else is second hand) i am getting 7.5 bar. This engine has been seriously abused. And I mean seriously abused

so you detonated on a set of seals that had been recalled by the manufacturer with a clear explanation that the seals were flawed and not treated properly for wear purposes

and you're complaining publically as if the seals are ALL bad?

No smart one. Those seals were never recalled. The ones that were recalled had a different problem and were made AFTER mine were. I actually asked them about it, and they said the ones with reported problems were sold a while after I bought mine. Get the facts straight before you start bitching.

My understanding is that they did not have a "window" of bad seals, anything before Dec 19th 2003 was suspected bad. They provided full recall of them and upgraded to a CNC cold method of finishing the seals.

Perhaps you should get your facts straight? I mean, after all....when notified, I pulled my seals and replaced, you did not...now you have no motor. You claim you ran lean, detonated, etc...what do you think that does to springs? It certainly doesn't increase their life.

You come on here like you want some type of support or a shoulder to cry on, trying to warn others of your misfortune, but you are really not an ideal candidate for evaluating the integrity of a seal. And what qualifies "like new" versus "new" on rotor housings? You used 320grit sandpaper on your rotor housings? Are you kidding me?

1). he's not talking about the springs buddy... look at the housings - they're scored. springs have a whole lot of nothing to do with that (especially if they're too weak)

2). Read the first post again... does that sound like 'crying'? What's your problem? Do you have a personal interest in RA or something? What's wrong with somebody posting some data on the forum?

Those housings as-is look pretty trashed, and while I wouldn't personally have used sandpaper on them, there's nothing to lose here.

The RA seals do not appear to be made out of a material suitable for direct contact with the housing surface. There's a reason mazda spent so much money testing, and even then it took a few tries to get it right. If this was the only case with scored housings, I'd be suspicious that something else caused the problem, however a few people have posted similar findings...