sergejcik

hi guys
im choosing between RA classic and atkins rotary
is anyone build their motors on both of them?
thanks

RotaryEvolution

iTrader: (30)

depends on what you are trying to accomplish and what engine you have.

if you have an n/a engine and want the longest life from it i would probably suggest paying a little extra for the OEM 2 piece seals, non cryo atkins would be second, RA would be third.

if you have a turbo engine and want to sacrifice engine life for durability of the seal than reverse the order of the 3.

there's other brands of seals too, but there is threads devoted to the seals all over and plenty of opinions based on them and everyone's preferences. just keep in mind, the softer the seal is, the more it will want to weld itself to the rotor housings, this is what causes drag lines in rotor housings and on seals. contrary to belief, the bendable/unbreakable seals are soft, the OEM seals are hard, Atkins seals are nearly as hard as OEM are, RA are soft and malleable. hard seals shatter, soft seals warp and cause compression losses which can actually still cause detonation and damage to rotors(caved in compression faces), broken iron pin lands from engine twisting, broken side and corner seals, etc.

the best way to build a good engine is to build it properly, take care of it, tune it well and keep it tuned. sometimes you are just unlucky and problems come up at the worst times, but that is unavoidable so there is also some luck involved in every car. some cars are cursed with bad luck(i had one car that blew up about 4 or 5 engines, then again you should double check other people's work), others have extremely good luck.

sergejcik

hi
my engine is street ported
i was thinking ra SEALS CLASSIC, BUT THEY CLAIM they are harder , you are saying they are softer
im confused
turbos are stock 99 spec
apexi ecu

sergejcik

also 3"catback

ROTARY_ADDICT-1

iTrader: (6)

READ HERE SOME REALLY GOOD INFO ON DIFFERENT APEX SEALS HOPE THIS HELPS YOU

https://www.rx7club.com/single-turbo...-seals-983085/

Sgtblue

iTrader: (16)

Why not stock MAZDA seals? Aftermarket doesn't always = better.

TTrotary7

iTrader: (5)

I agree with sgtblue, from everything i have read and witnessed the OEM seals work fine, (unless you are building a race motor that will operate at higher than 8500 RPMs constantly) Race motors that require a more "constant" rebuild cycle would benefit from the "harder" seals, though they can damage the housing...

Mazda seals is what i am using on my engine rebuild (2nd one).

evo_koa

iTrader: (2)

exactly

RotaryEvolution

iTrader: (30)

because a "harder" seal sounds more indestructable? truth is a softer seal will bend before fracturing. a softer alloy will also be more prone to fusing to the chrome sleeve during combustion, but in the event of detonation will not shatter like the 3 i will list as the hardest seals, and not of the "unbreakable" category we generally consider.

the HARDEST seals are actually ceramic, followed by OEM, then followed by Atkins which appear to be a blend of cast iron alloy. these are just things i have noticed in how the seals react to detonation in the various and numerous failures i have seen in my time building the engines.

why do those builders really call their seals harder? i do not really know.

the HARDER the seal is the less wear you generally will find, ceramics wear the slowest followed by OEM and then Atkins seals. this is good for low power and daily use.

the SOFTER indestructable seals sacrifice longevity and potential compression losses from clawing the housings to be able to handle detonation cycles without destroying your turbo(s). BUT, if a detonation cycle is strong enough to warp the seals, it may be strong enough to break irons, dent rotor faces and/or break other rotor seals.

There is no best apex seal in reality, but some do give you a very small margin for error. i have had the unbreakable seals run through detonation and lean events that would destroy factory seals and without much harm to anything, i have also seen the wear that some of the unbreakable seals are capable of.

the anwer is, there is no good answer. some people have had great success with ceramic seals in turbo applications, some have seen how destructive they can be. every seal can wreak havoc in some way, no matter how well you think you are treating them.

carbon seals are a definite no, followed by ceramic seals as a possible maybe, if you have all your moons and stars aligned. all the others, bets are off as to what is best for any given situation, i tend to sacrifice longevity for the ability to handle a lean cycle and some detonation though... but that doesn't mean i haven't pulled apart an engine with them and had to replace 2 rotors and all their associated hardware, resurface rotor housings, or sometimes a replace a broken iron... i do tend to prefer that over a rotor, housing, seals and potential iron and/or turbo though.


there is no way to make an indestructable rotary, no matter what ANYONE sais. i've tried, many times and in many ways, the damage just changes location. i've also used just about every seal out there.

zli944

iTrader: (2)

Not being an expert in metallurgy, can't say in concrete terms which apex seals are better, only anecdotal and advice from other vendors.

I've heard from 2 separate vendors that Atkins is... not the most desirable in terms of seals. They both suggested OEM.
That being said, they also qualified that statement for 3rd Gens only; aftermarket seals might be ok for non-turbo cars.

The consensus in this thread seems to be OEM and I'll thumbs up to that as well.

RotaryEvolution

iTrader: (30)

i actually used to prefer Atkins to OEM, because when they fractured they would only break the sharp edge off the long seal instead of fracturing into multiple pieces like the OEM seals would. however in terms of durability in the face of detonation, Atkins and OEM are about equals and semi low on the list.

multiple fractures of an OEM apex seal almost guarantees rotor and housing damage and possible turbo damage. the tiny bit the atkins seals spit out generally would only put a scuff in the exhaust port and almost all parts would be salvageable(i saw this scenario on at least 10 engines, it was readily repeatable). that is not to say i think atkins are the best seals, they however have a place on the list of parts saving internals that i have listed ahead of OEM. when an OEM seal goes south, it takes other things out with it, expensive things.

the only thing bad i can say about atkins seals is they are still semi fragile for turbo use, but so are Mazda seals.

so yes, i guess i am defending atkins, even though i no longer use them in turbo engines. i do still think they are a great alternative for non turbo engines. i used them a decade ago and i haven't heard any mass hysteria of engine failures, in fact almost all of those engines are still out there, somewhere.

for stock applications, OEM works "okay". even mild mods can put your engine at risk with them though. the main reason people suggest OEM is their hardness allows them to have the best longevity(aside from ceramic, but i already talked about that). people don't often suggest the other seals because they tend to claw and gouge housings, ALL aftermarket seals have the ability to do that, which is why for long term wear OEM is probably best. if you ever plan on making over 300whp, yeah, get rid of OEM and expect more regular teardowns and internal cleanings/inspections/touchup work, the headache is necessary unless you enjoy seeing half an engine trashed along with a turbo.

part of owning a rotary car is learning how to do this stuff on your own. since people have been leaving the shops behind for this, i will admit that it is in all your best interest to learn how to build your own engines. it won't be your first or only rebuilds if you keep the car for any number of years. only the well off with clean fingernails can own a rotary car and never have to worry about dirty hands. i have had my personal car's engine apart roughly 5 times since i bought it in 2003. if i had to pay a shop to do it, i would have ditched the car a long time ago due to the financial hardships it would have given. going with OEM seals won't save you any form of future headache if you ever have even an inkling to modify the car.

i've built over 400 engines, used many types of seals and semi retired from it all now, i try to be as unbiased as possible when giving any advice. i have nothing to benefit from here anymore.

BLUE TII

iTrader: (9)

I don't have near as much experience of RotaryEvolution in building so many engines, but possibly more experience racing/rebuilding my own rotary.

I agree with what he says, and offer another alternative/compromise that I arrived at.

3mm OEM apex seals.

On my S5 TII it shifted the cast iron side housings to the weakest link (they break before the apex seals), though it may be different on an FD (FD side housings are stronger).

3mm steel seals don't like high rpm though.
8,000rpm redline and don't sit on it like you can with 2mm seals or it will chatter your housings.

I haven't found 3mm RA RA/Super Seals to be tougher than stock 3mm, but weaker. After a while they get tiny fractures on the wear surface from friction/welding and crack in half.

I am sure RA is "tougher" than stock when new (based on my experience with 2mm RA and stock), so RA still would probably be strongest for high power drag racing where the engine is being rebuilt before 20,000miles.

RotaryEvolution

iTrader: (30)

i can vouch for that, the 3mm OEM seals are twice as hard to break as the 2mm but the weight they carry makes them hard on the housings at high RPMs. 3mm are still destructable but i saw failures much less in the engines that ran them over the 2mm. you will produce more wear with 3mm as a tradeoff for the reliability assurance.

i have never found it necessary to run any of the bendy seals in thicker forms over 2mm. atkins, OEM and ceramics being the only exceptions since i consider them to be very similarly categorized to OEM in fragility and hardness.

Brettus

I just recently blew an engine with RA seals in it . The seals survived but as rotary evolution mentioned the damage just shifted to elsewhere in the engine . Plus there was the beginnings of some bad wear lines around the housings which I put down to the E50/RA combo I was running. After much reading and thought . I decided to run stock seals along with a high concentration of ethanol as an octane boost . Along with this I decided to tone down my power ambitions to levels I know are somewhat safe . Fingers crossed .

bpdchief

iTrader: (7)

We run stock Mazda seals in the FC turbo and had no problems for years. Until recently when the wastegate line burned through and yeah, total destruction. Tearing it apart to see what the damage is. I run Atkins in the FD. No problems. 2 rebuilds, very little wear to the housings. I have a friend who runs goopy seals on his fd. He just had some detonation, that was enough to dent a rotor and crack a corner seal, but the engine and the seals survived. Pretty convincing evidence that they are pretty good but they do wear the housings. The more reputable engine builders here like Rotary Evolution are people you should listen to.