Erdin

i think the Fd is faster of the mark but the supra will take a fd in the long run, speaking from expirence. this is in stock form.

EpitrochoidMan

God damn-it. I love reading informative posts on this forum, but some of you need to use some common sense and back-up the things you say.

There seems to be 'real' evidence that 3mm seals have benefits. To say the 2mm seals are what mazda designed them with and so they are best is just a cop-out. I will be the first one to say that most of us are probably not smarter than the factory engineers. But with the 'that's how it was designed' cop-out, you should all be running stock motors.

Take off your different off-set wheels and aftermarket suspensions, do they make the car handle better, sure, but they change the SAI among other things, and mazda didn't design it like that, so it must not be as good as stock.

Take off your intercooler upgrades, larger turbos, coil-overs, etc. For every upgrade there are pro's and con's and falling back on 'well that's how it was designed' is just a nancy cop-out.

v8eater

I got 2mm 2peice seals for sale for both rotors. brand new still in the package 190.00 includes shipping. you will not find them any cheaper. Their are for the FD, come on all you engine builders. emil me Basspl4u@aol.com

JohnRX-7UK

Hey ArtGuy.
Couldnt help noticing you have a fan mod can you give ma any more details ??

John

Krazidawg

I guess its time for me to put in my two cents. I went with the stock 3 piece 2mm. Being a novice to rotary engines my first thought after I leaned out my engine on my 87 Turbo II was "Damn when I rebuild I should go to 3mm". I went to my mechanic at Rotorsport2 and he said 2mm is the only way to go, 2mm seal better and they weigh less than 3mm therefore making more power because of the less weight. So then I talked to Dave Gibson at FC3S.org and he said if I want the added security of the 3mm just cryogentically treat the 2mm apex seals along with all the housing and internals and I would be bulletproof provided I tune the engine right and upgrade my fuel. Needless to say he is right, my car is only streetdriven and I'm going to be running 10psi low boost and 12psi high after I install my FCON and FMIC and I should be okay for at least 200,000 provided I do all the preventive maintenace.

Maxwell

keep this going- I want to hear more from jeff48

tomaszjc7

Damn I just ordered a set of 3mm seals from rotary specialties. This thread is really makin` me think. When i talked to adam from that place he said he will only sell 2mm seals to people running NA motors. He said he would never install or recomend anyone else to install 2mm seals on a turbo charged engine....?? I'm going to be running a 13b street port at 17psi with Stage II BNR's running parallel, Anyone think 2mm would still work better? And no one ever answered that guys question about the type of seals the 787B was running, or did I miss that?

tomaszjc7

HAH it doesnt matter anymore!!! http://www.ignitionsolutions.com/pro...booster.shtml#

tomaszjc7

I mean http://www.kdrotary.com/new.html

fc3s.org

We built Loi Song's (SportCarMotion.com) 94 FD engine with 3 piece 2mm seals that we had cryo treated, and it is running 445rwhp with a T04R, and just over 1bar on pump gas. People who say 2mm seals are bad, are worried about warranty work. I have no problems using them or tuning them on high HP rotaries, weather street car or dune buggy, running high boost, and having no problems.

Just my opinion, but everyone is entitled to their own.

JScott

Hey Dave, so.... what now since we can't get the 3pc anymore. Any experience with the new 2pc, 2mm Mazda seals?

See my post in the "Hurley Seals crap" thread.... but I've popped 2 engines w/ Hurley's in 2 months now.

ErnieT

iTrader: (2)

3mm seals are good to use if you are concerned about your tuner's abilities. IF you have KDR tune your car, you had damn better have 3mm seals.
That said, Demetrios K. (Reactive Racing) has stock 2mm 2piece apex seals in his car and makes 770rwhp. Nuff said!!!

BDC

You pretty much nailed the issue on the head, Ernie.

B

BDC

That, much like 95% of the claims made on this thread and on this subject, isn't a real way to empirically test this stuff, unfortunately. The claim is inadvertendly bogus; testing of differing apex seals needs a litany of ever-remaining constants as well as a _very long time_ to test it all.

If we can refer to things such as malleability, Rockwell hardness scale, durability, tensile strength, etc., then we can get to the real nuts and bolts of this. As Ernie just posted, stock seals are capable of humongous numbers. There's also more evidence coming up that 3mm may not be so great for low-end compression numbers as well as shearing loads put against the edge of the seal at tigher points along the rotor housing (near TDC and BDC respectively).

Think about this issue carefully, folks, and don't buy into some of the things that alot of people will try and sell you.

B

JScott

That said. The low end Hurley's just aren't up to the task of 400+rwhp IMO. My new Mazda 2pc, 2mm are holding up well. 11.54 @ 121.5 mph w/ a lousy 60ft. I got booted and couldn't work on the launch....

Shamrock.James

can someone give me a weight differnce between 2mm and 3mm seals??

hyper7

ok, well im not to say what is the best, however i will state what my uncle's friend at racing beat told me along with another friend i made over there last week. 3mm seals are a waste of money! for a fews reasons as stated, they will create more friction, will still break if motor is untuned, and expensive for not having any performance better than stock 2mm. As everyone should know any seal is going to break unless the car is tuned. detonation is the enemy NOT the apex seal! 2mm factory mazda seals are in racing beat's bonneville rx7.....i wonder why! as far as weight difference between 2mm or 3mm, what would it matter? if you are looking to lose weight lighten the rotor. it seems that people are mistaking that 3mm are better but it really comes down to them thinking they are and feeling that thicker is better, when in reality it is not. remember what ive said came from a source who has been working on rotaries for 31 years. Krazidawg's post is a perfect example of why 2mm is the way to go.

Shamrock.James

the amount of force placed by the apex seal on the housing dramitcally increases as the RPM rises therfore any difference could be massive. the weight of the rotor has nothing to do with it.

RETed

Damn, I can't believe this thing is still going...

And I can't believe I never mentioned this...

Paul Ko @ K2RD had a Brinnell hardness test (not Rockwell - different scale) done on the stock 3-piece 2mm apex seal (before Mazda changed over to the 2-piece 2mm ones now), and the results were interesting.  The stock seal showed 60 hardness at the tip versus 40 hardness at the "back" end of the seal - this shows the significance of the electron beam hardening process done to the stock apex seals.  I *KNOW* the Hurley are are not hardened, and I think the Atkins ones aren't either (hell, Atkins has explicitly stated you can't even run over 15psi with THEIR apex seals!), and I have a feeling the Rotary Aviation apex seals are not either (but no proof of otherwise).  This hardening process cost money, and all the "cheap" seals do not have such a process done - this is why they are all cheaper.

These guys try to push it off as "breaks in quicker" and "doesn't damage the engine when they fail" advertising, but it's all in the physics.  Anyways, this is off on a tangent...

Bottom line, if you detonate the motor, it's going to kill both the 2mm or the 3mm apex seals...


-Ted

maxcooper

Heavier seals are said to be more likely to "float". I presume this means over the cusps of the rotor housing (combustion area and above the exhaust port). It makes sense, but I don't really know how significant the effect is.

I have been shopping for seals lately and while I am hesitant because of the price, the ceramic seals are very light and come with very heavy springs. That seems likely to keep them sealed against the rotor housing very well. I would be concerned about heavy springs with metal seals, but apparently the ceramic seals are easy on the housings, so the heavy springs are okay. I did have some minor chatter marks even with stock Mazda 3-piece 2mm seals on my last motor.

-Max

JScott

So, how's everyone else doing w/ the new 2pc Mazda seals, and the new R.A. seals as well? My Mazda's are holding up fine but it's also been winter and I haven't exactly been driving the car that much or that hard. I have made several wot runs and of course my 2 trips down the 1/4 mile before being booted last fall.

The R Aviation seals sound VERY promising so I hope they're doing the job for those already using them.

re10

Then why are they still selling them

rxAustin

Just to add more fuel to the fire:

Fichtel and Sachs found that increasing seal size from 1.5 mm to 3 mm dramatically reduced chatter.

Anyway, 3mm seals give you that much more margin against getting a bad tank of gas, sucking some air into the fuel, etc. (things that can happen regardless of tuning)

WaachBack

iTrader: (21)

Ok, could someone please post only the facts about 3mm vs 2mm here:
3mm:
1.
2.
3.

2mm
1.
2.
3.

madsci

3mm
1. Stock on all 1974-1985 engines. Require machining to use 1986+ rotors. Bad machining = binding.
2. Extra margin of safety.
3. Probably slightly less RPM capability.
4. Greater beam strength
5. About $66 each from Mazdatrix because nobody buys them

2mm
1. stock on all 1986+ engines
2. will handle any amount of boost as long as nothing ever goes wrong
3. slightly more RPM capability
4. Probably largely responsible for the common conception that 1 ping will destroy a rotary