Searched through google doesn't reveal much.

Where can I find wear data, material data on both the apex seal as well as the contact surface of the rotor housing, thermal dynamics and distance traveled/RPM?

...call the manufacturer and ask for a datasheet.... that's not something you're likely to find online... at least not easily.

Searched through google doesn't reveal much.

Where can I find wear data, material data on both the apex seal as well as the contact surface of the rotor housing, thermal dynamics and distance traveled/RPM?Why, aren't you long past the need to produce high school research papers? :D

Material? Carbon steel, ceramic, ham and cheese, take your pick.

Wear data? Some N/A engines last 200,000 miles or more. I think it's safe to say that unless the engine experiences detonation or excessive abuse, the life expectancy of a set of apex seals is roughly equivalent to that of a piston ring set. They serve basically the same purpose, after all.

Not sure what you're looking for on thermal dynamics.

Distance traveled is tricky, because the seals don't make a full circuit of the surface of the rotor housing until three revolutions of the eccentric shaft are complete. Blake Qualley (former owner of www.rotaryengineillustrated.com) would probably be able to tell you how to calculate the circumference of the epitrochoid shape of the inner surface of the rotor housing. Divide by three and you'd have distance traveled for 1 revolution of the eccentric shaft.

Here's a pretty decent paper on the math involved with a few other data points that might interest you.

http://www.personal.utulsa.edu/~kenneth-weston/chapter7.pdf

Once again, Jimlab, u da man.

*I had a feewing that u'd respond to this thread........*

;)

That's all you were looking for? How about how the stock seals are a ferrous based alloy (carbon of course being one alloying element, no telling what else may be in it) with a localized "flame hardened" sealing surface for wear resistance while leaving the majority of the seal unhardened to retain the ductile properties of the original alloy? I thought that was common knowlege.

Distance per rpm is easy, each apex seal travels one epitrochoid circumference per three revolutions. For 8000 rpm it would be 8000 rev/min * 28" (rough guess) / 3

And its internal displacement by four stroke piston standards is 1.3l, while it consumes the same amount of air as an equivalent 2.6l piston engine would in two revolutions, and its total internal displacement is theoretically 3.9l. There are two power pulses per revolution for a two rotor.

A friend of mine did an engineering analysis of a TII shortblock for a project and came up with factors of safety for the various parts ranging from 1.5 to 6ish. Apex seals came in at about 3-4, but this was for a non pinging engine making ~200ish hp.

The more info the better.

keep it coming.

It's for a friend of mine that's a machinist. He is doing some research on apex materials for a project.

It's for a friend of mine that's a machinist. He is doing some research on apex materials for a project.It's my opinion that ceramic is a waste of time and money, because the expected lifespan of a high horsepower rotary isn't measured in hundreds of thousands of miles, and ceramic seals break just as easily as carbon steel seals under detonation.

Sandy Linthicum had Roger Mandeville tune his Motec ECU for SCCA competition. From what he told me, they broke two sets of ceramic seals @ 10 psi before finding out that the Motec harness was wired incorrectly from the factory, but the lessons are twofold; 1) ceramic apex seals aren't bulletproof, and 2) that you can detonate and break apex seals even at stock boost levels, which some people were reluctant (if not incapable) to admit.

Despite opinions to the contrary, ceramic seals take out your turbo(s) just as easily as carbon seals, as you'd expect from any type of hard debris hitting an Inconel turbine wheel spinning at 100,000+ rpm. The only benefit they may provide, besides extended service life, is to save rotor housings when they break. However, I've never seen evidence to support that, and it's likely just more propaganda from the same people who don't think they'll damage turbine blades.

In my opinion 3mm seals are also a waste of time, unless A) your engine already had them, or B) you can't afford new rotors. The racers who build multiple engines don't waste money or time on 3mm seals in my experience, because 2mm seals seal as well, handle as much boost, and don't require as much lubrication to reduce wear. 3mm seals are an option for saving a 2mm rotor that no longer is in tolerance, but going to the expense and trouble of machining rotors for 3mm seals for a fresh engine is a waste otherwise.

When talking to Francesco Ianetti (maker of the ceramic apex seals sold through Mazdaspeed) about seal material and width, he mentioned that 2mm seals had been tested reliably to 45 psi. He also mentioned that various widths had been tried, including 4mm and 6mm, and except for accelerated wear, none was proof against detonation or an improvement over a good 2mm seal. "3mm" and "ceramic" simply became the "magic bullet" around 1998 that everyone seemed to think was the best possible combination, but after a year or two, the madness had worn off. :)

besides extended service life, is to save rotor housings when they break. However, I've never seen evidence to support that, and it's likely just more propaganda from the same people who don't think they'll damage turbine blades.



I pulled apart an engine in late August 05 that had damage to both the rotor and housing. The engine let loose at 11psi. I'll tell you what though, I was in the car, and heard audible detonation! The damage was done, but the car didn't let go just then. We were tweaking ignition a little more when the motor finally took a shit. The motor is trashed long before oyu would ever hear audible detonation on a rotary, so this leads me to believe the the ceramics may be stronger.

I personally use only stock mazda seals. I've had a set of hurleys and they were complete shit -and another heavily hyped seal at introduction.

Everyone I know personally wh has used RA seals has warped them in no time. I know that rx7store has had to redo ALOT of motors during the brief time they were using them.

I would conjecture that ceramic seals do more damage and wear/tear to the rotor housing due to it being a harder material. Would this be true?

I would conjecture that ceramic seals do more damage and wear/tear to the rotor housing due to it being a harder material. Would this be true?I didn't see any excessive damage over a mazda seal. Sometimes you make out ok with a popped motor, usually you don't. The turbine was undamaged. Keep in mind this thing pre detonated so hard it dented the rotor.

I have the RA seals.

So far after 15K+ miles no problemo.

This is the first time that I heard that they have warped.

The only problem that I heard is that if u use their springs, as oppose to the factory ones, they may "sag" from the heat beyond 10psi according to the guy at RA that i spoke to on the phone.

I have the RA seals.

So far after 15K+ miles no problemo.

This is the first time that I heard that they have warped.

The only problem that I heard is that if u use their springs, as oppose to the factory ones, they may "sag" from the heat beyond 10psi according to the guy at RA that i spoke to on the phone.

I have two friends who used RA seals. Both lost compression shortly after break in. By losing comp., I mean compression numbers dropping to 30-50 psi. Not blown. Are push starting the car and letting them idle for n hour or too, they would slowly regain compression.

I pulled apart an engine in late August 05 that had damage to both the rotor and housing. The engine let loose at 11psi. I'll tell you what though, I was in the car, and heard audible detonation! The damage was done, but the car didn't let go just then. We were tweaking ignition a little more when the motor finally took a shit. The motor is trashed long before oyu would ever hear audible detonation on a rotary, so this leads me to believe the the ceramics may be stronger.My first indication that my second engine (a junkyard core) let go was the sparkly dust behind the car as the rear turbine was destroyed (running ~14 psi with full mods and M2 reprogrammed ECU). That happened in September/October of '97 and the engine continued to run pretty well at higher rpm, if smoke and idle badly, until it was pulled in May of '98. In fact, at a local club dyno day in December of '97, it put down 238 RWHP @ 10 psi with a downpipe, midpipe, stock catback and stock IC. It had low compression on both front and rear rotors and when disassembled, looked like someone had tried to hammer them round.

My first engine, on the other hand, suddenly died while cruising at 70 mph without prior warning (broken corner seal came loose) and would not idle. I was able to limp it home, but it was not drivable and only had bad compression on the rear rotor. Both had stock apex seals.

I don't think there's any valid correlation that can be made between level of detonation, apex seal material, and how long the engine remains usable after the catastrophic event leading to its demise. Ceramics are stronger, but only marginally so. By the time you know you have problems, it's too late regardless of what your apex seals are made of. The only real questions remaining are how much internal damage has been done, and whether the engine will keep running. :)

My first indication that my second engine (a junkyard core) let go was the sparkly dust behind the car as the rear turbine was destroyed (running ~14 psi with full mods and M2 reprogrammed ECU). That happened in September/October of '97 and the engine continued to run pretty well at higher rpm, if smoke and idle badly, until it was pulled in May of '98. In fact, at a local club dyno day in December of '97, it put down 238 RWHP @ 10 psi with a downpipe, midpipe, stock catback and stock IC. It had low compression on both front and rear rotors and when disassembled, looked like someone had tried to hammer them round.

My first engine, on the other hand, suddenly died while cruising at 70 mph without prior warning (broken corner seal came loose) and would not idle. I was able to limp it home, but it was not drivable and only had bad compression on the rear rotor. Both had stock apex seals.

I don't think there's any valid correlation that can be made between level of detonation, apex seal material, and how long the engine remains usable after the catastrophic event leading to its demise. Ceramics are stronger, but only marginally so. By the time you know you have problems, it's too late regardless of what your apex seals are made of. The only real questions remaining are how much internal damage has been done, and whether the engine will keep running. :)

I wasn't stating that an engine can't sustain damage and run well for some time. But we knocked hard enough that I was like holy shit! Did this thing just detonate?!! I've blown my fair share of motors and never heard predetonation ona rotary engine. Typically they will have fatal damage long before oyu heard them knock.

I would conjecture that ceramic seals do more damage and wear/tear to the rotor housing due to it being a harder material. Would this be true?Not in my experience. Ceramic is harder, but more brittle.

I wasn't stating that an engine can't sustain damage and run well for some time.I know, just adding my experience.

Typically they will have fatal damage long before oyu heard them knock.Agreed.

Agreed.

Which makes me think that their is the possibility of them being more durable in the presence of detonation.

The engine had 10k or so on it on leading only. Maybe 1k with trailing hooked up. Now this is only one motor, one situation. Obviously not enough evidence to draw any conclusions in stone. But its not the first time I've seen a dented rotor from detonation(which is typically from pretty severe knocking), and those cars went boom instantly. And without audible knock before it let go. Obviously audible destructive is going to be more destructive.

Which makes me think that their is the possibility of them being more durable in the presence of detonation.I'm not arguing that they don't hold up "better". I'm arguing that the difference is negligible at best and irrelevant when the outcome is the same. :)

One "nice" thing about rotory engines is their ability to limp home, instead of being stuck on the side of the road after they have a hiccup.

MEDDLE,

Ur friend's RA seal ailments sorta sounds as if they lost spring pressure.

I'm arguing that the difference is negligible at best and irrelevant when the outcome is the same. :)

Point taken. I know form personal experience that they definatly aren't easy on the motor when they go.

One "nice" thing about rotory engines is their ability to limp home, instead of being stuck on the side of the road after they have a hiccup.

The first time I wired up a haltech I wired the cas to the plug, not directly to it. I had my timing 50* off and the car drove decent! I couldn't figure out why I couldn't time the car. d'oh

MEDDLE,

Ur friend's RA seal ailments sorta sounds as if they lost spring pressure.

Both people had their motors assembled by rx7store. Rx7store uses mazda springs. Kan has also told me to avoid RA seals. He told me he won't tune a car if he knows it has RA seals in it.

One "nice" thing about rotory engines is their ability to limp home, instead of being stuck on the side of the road after they have a hiccup.I think you've got that backwards. Rotary engines are notorious for failing dramatically when they do fail, and it's more or less a crap shoot on whether you're going to get home or not under your own power.

I must be lucky 6/6 times. ;)

I think you've got that backwards. Rotary engines are notorious for failing dramatically when they do fail, and it's more or less a crap shoot on whether you're going to get home or not under your own power.

As long as it doesn't die when it goes, you can usually get them home.

I've driven a car that didn't pulse on any face of the front rotor about 40 miles one time. My pump tune wouldn't support 23psi for some reason.

I must be lucky 6/6 times. ;)

BATMAN, isn't you cra pretty stock? How are oyu popping so many?

As long as it doesn't die when it goes, you can usually get them home.Yes, as long as it doesn't die immediately, usually you can limp home.

Unless you window the block on a piston engine and lose your oil pressure or supply or hydrolock it, you're getting home 99.9% of the time. They shrug off detonation that would require a rebuild on a rotary.

well 4 popped, all at 14psi

1 - Forgot to add oil (long story)

2 - overheat.

Even the one with no engine oil, i managed to drive it 2 miles to a gas station to put some oil.

The car did require a qt of oil every 200 miles (i actually drove it to and from seven stock).

here's a list of the mods on my car:

supra fuel pump
PFC
1300 secondary inj
SMIC
efini y pipe
UIM removed warm up butter flies
just about everything from the intake to the rotor face and exhaust was ceramic coated.
51R battery tray
ghetto CAI for stock box
SS intake pipes
HKS BOV
lightweight flywheel
ACT extreme pressure plate and clutch

i may have left some other stuff out

Alright, I got a question about driving your cars home when your rotary engine takes a crap.

What gear, speed, and rpm are you at while you're driving home? And I take it that you're also blowing out a cloud of smoke as well?

Alright, I got a question about driving your cars home when your rotary engine takes a crap.

What gear, speed, and rpm are you at while you're driving home? And I take it that you're also blowing out a cloud of smoke as well?

I just ream it to get home and keep the revs up at stop lights. Doesn't matter what gear, or speed. I always start with a reman for a new motor, so I'm not worried about tearing shit up further.

I was just curious because when my motor blew I couldn't drive my FC at all. It seemed like it would only run when it's either idling or over 3000 rpms. Other than that the motor just wouldn't run. So I ended up getting it towed home :mad:

Well a blown motor that idled will definatly drive home with no problems.

I was just curious because when my motor blew I couldn't drive my FC at all. It seemed like it would only run when it's either idling or over 3000 rpms. Other than that the motor just wouldn't run.Yep, that's one possible outcome. Keeping the rpm up smooths things out and creates enough power pulses that you can get somewhere despite being down 1 or 2 (or more) "cylinders". :)

my fist engine blew bad.

didn;t know it was kaboomed and just kept on driving it with full exhaust.

At the time i didn't know that i was boosting at 18psi.

But apparently it had detonated enough times to clear out 2 apex seals in the rear rotor.

I heard metal bouncing out and thought it was parts of the spark plugs.

I actually limped it to the mazda shop.

how about titanium?

it's brittle.......

Titanium is also incompatible with the chrome surface of the housings: galling is one possible outcome of running titanium on the stock housings.

I used RA seals in my large ported NA rotary and it has 120ish comp on the front rotor and 100ish on the rear after about 15k miles. I think the low compression on the rear was me having only the side seals with the largest endfloat clearance left when I was assembling the rotor (I was reusing the side seals, lol).

RA seals appear to be incompatible with the chrome housing surface too, although in a different way. They are so hard, the chrome get galled, not the seals. Have a look at the rxclub's rotary performance section for a long thread with pics of what RA seals do to housings.

They did have early problems with warping due to stock feed speed violations of their original subcontractor, which have been resolved to my knowlege.

After experimenting with rotary porting and rebuilding to the limit of my attention span, I would go for the new 2mm 2pc oem seals if I were to build another rotary. But I'm not, so it's off to V8 land for me, oh yeah!

They did have early problems with warping due to stock feed speed violations of their original subcontractor, which have been resolved to my knowlege.



The two RA motors I mentioned purchased the RA seals this past summer. Both engines were assembled@ rx7store. Again, this is not internet fanboy hearsay bullshit. These are cars I know/work on. Fuck I had to correct rx7store's tune on one because It looked like ryosuke did the timing maps.

do u think the problem is with the rx7store assembly?

Perhaps I'm "lucky" with regards to no problems on the RA seals and springs.

Then again, I did ceramic coat the rotor face.

Not sure if that had any good effects on the seals from reducing heat.

Well, I'm not going to speak against rx7stores assembly. I see no evidence that they did anything wrong assembly wise. They "tuned" one of the cars, which was a fucking joke. That car had the motor installed in the car which the owner shipped up there. Both cars lost compression upping the boost to bring them to where they should be. One was a t-78, the other a 60-1. Both had a drop in compression around 15 psi. Maybe they had a bad batch, who knows. I wish you the best of luck with your RA seals though.