bbmac

I am just about to begin a new project and am looking at high hp and want the engine to be bullet proof. I've been hearing good things about rx-7 specialties 3mm apex seals and how industructable they are, but don't know anyone personally who has them. when I called the shop to get the low down I was told that carlos gonzalas is running them in his race car, which is a bonus.. I also like the fact that it looks like the are using the factory end piece.

Anyways they FINALLY changed there piece *** website and the seals look promising. what do you guys think? it would be nice just cause they are local( no shipping and hassel) and if there is problems they are only a drive away.

Have a look at give me some feedback!!!http://www.rotaryengine.com/productp...0apexseals.htm

Chris Ng

Hmmm... puzzeling because from previous comments you have made on this forum and on the local calgary forums, you have represented yourself as someone who works for rx-7 specialties... Shouldn't you already know all you need to know about these seals?

And yes, their old website sucked.. as for the new website.. well, It has more links to press that lead you to some new pictures..but it's still kinda sucks and I see Adam has expanded his shop to cover the whole gammut of modifications you can do to a rotary motor..

As for the his new seals.. Last time I was down there, Adam gave me a demonstration of his new seals when compared to hurley, stock, atkins seals... basically he took each of the seals, clamped them in a bench vise.. all the other seals shattered, while his seals simply distorted.. upon taking a large mallet to the seals on the workbench.. adams seals dented, but stayed intact, while the other seals once agin broke and shattered.. adam's seals were not as brittle as the other seals.. The demonstration was certainly impressive to see, and I think the point he was trying to make with it was that his seals would resist breaking apart due to detonation...
However, there is a question as to the "hardness" of a seal.. is a seal is too soft, it will wear quicker, and also wear the rotorhousings quite a bit quicker as well.. Adam's seals were soft enough to bend with your hands. they kept their bent shape mind you... while the other seals would simply snap in half if you had the strength to bend them by hand..
I guess the only way to tell if they work or not is to try them out yourself though... in looking at his seals and comparing them to RA seals, they looked very similar..

just my 2 cents..

Chris

SAiamNE

uhhhhh boy.... here we go......

For what it's worth..
My engine was rebuilt there along with there new seals.. After roughly 30 000Kms on my S5 NA the compression is ~85-90PSI..

rx7_turbo2

Should the comp numbers not be ALOT higher than that? I'm pulling right around the 100psi range on a turbo motor with only 2000kms.

I don't like 3mm seals, I've written **** on them before, but I'm a nobody so....

Chris Ng

Smirk.. nonono.... I'm tired of bickering....

I was just stateing my first hand observations of the seals from the demonstrations that was shown to me at the shop..

Was your motor rebuilt with 3mm seals?

SAiamNE

No i don't believe so..

Amur_

www.rotaryresurrection.com

bbmac

Thanks for the input guys. I am doing this project with partner and the decision isn't entirely mine because he is funding the project. We haven't decided whether or not we are going to go 2mm or 3mm. I to witnessed the durability test as I worked there last summer, however they had a long end piece and I understand the material has changed since then. No offence to Adam and by no means am I trying to start something, but naturally when I asked him what he recommended he told me his seals would be the way to go but I am concerned as I will be running high boost(20 psi +) . Although Carlos may be running them I want to hear it from soemone face to face. Regardless of 2mm or 3mm does any one have any recomendations?

Amur_

https://www.rx7club.com/showthread.p...16#post4219516

Alak

iTrader: (9)

Just to throw another boxer in the ring, Im willing to bet Carlos Gonzalas probably has like 20 engines in a trailer. Im also willing to bet that he uses a new engine every race.

Im also willing to bet that I dont even know who Carlos Gonzalas is. And Im willing to bet that my *** will come into contact with a hot surface very rapidly for saying anything.



*Runs away at a very rapid pace*

black93RX7

I had a rebuild from Adam last year with 3mm seals, street port, one piece corner seals, dowel pinned and anti-dets in the trailings (capped spark plugs)

The car has had 60psi compression in both rotors since it was installed and has run solid for a year. Approx. 6000 km. Spent alot of time of the dyno (~40hrs) and is daily driven.

I put down 388rwhp @14psi with a T-78 last week on a mustang dyno.

With 60psi cranking compression my motor feels very strong. However I have nothing to compare it to.

Adam told me cranking compression doesn't mean anything. So far he seems to be right. According to many others I have talked to my motor should be toast. I guess I'll find out.

bbmac

thanks again guys for the input

SAiamNE

I'm not trying to be rude or anything but i'm just curious as to how you check compression then?

black93RX7

That's a very good question. I asked that exact question and was never really given a straight answer.

I guess when your motor blows it means you have really bad compression and should probaly replace it.

Chris Ng

my original motor made 70psi compression from day one.. with a td07-25g i dynoed at 371rwhp @ 14ish psi .. now keeping that in mind, you can say, wow I made alot of power, cranking compression really doesn't make a diffrence! ... on the other hand, what kind of power would I have made if my compression was at 100psi??

I guess the answer to that will come once my motor is back together and broken in.. I'll be running the same setup as before, but this time with 2mm seals, and hopefully seeing higher cranking comp #'s ... If I endup making over 400rwhp on the new motor, then I would be led to belive that cranking compression does in fact matter...

Black93rx7 - As you have said, you have no other basis of comparison.. you're making 388rwhp on your motor.. and I betcha it feels strong.. but what if 388rwhp concidered low concidering the size of your turbo? ..

offrotor2

--- again, stupid thread to start, way to go!

but anywho! Jreynish could back me up on this, (his vast knowledge on physic 'er what ever he knows...) Cranking pressure would be less that you might think on any rotary you test, cause it relies on centrifugal force to increase its own pressure.. hence the high HP on a 60 psi motor, the motor is'nt being tested @ 2000 or better yet 5000 rpm. Again Cranking pressure.... this must all a have to do with seal spring pressure er something, who knows.. but hey if your car starts on cranking pressure, dont worry about its all is good, if you HAVE to dump loads of ATF in it everytime you need to go, then..... well, Ask mom and dad for some money!

Chris Ng

You need to do a little more thinking.. Take 2 motors.. both are rebuilt.. 1 motor has low cranking compression numbers, and the other has high compression numbers.. since these 2 motors have just been rebuilt, we know that neither motor are blown.. all the apex seals are intact and all seal springs are intact..so why such the discrephency in compression readings? do you honestly belive that once the motor is spinning at 2000 or 5000 rpm that both motors are then going to seal just as well as each other? that the cause of the low compression readings at crank speeds is because of seal spring pressure? that centrifugal force is goign to equalize things?? Even then, why would the builder decide to use components that they know will promote low compression numbers?
Mazda specifies compression readings to be within a minimum range.. if cranking compression numbers don't matter, do they specifiy this simply for laughs?

okay.. so let's say it isn't seal springs that are causing the low compression numbers.. what else could it be then?? out of spec housings, rotors, seal lengths.. now if these are the cause of the compression numbers, what the heck was the rebuilder doing using these parts?

offrotor2

I am thinking... centrifugal force is how a rotary works... as for the compression numbers being different in 2 completely rebuilt motors is simple.. Not every pease is EXACLY perfect, the seals NEED to wear, and the housing needs to wear, so the 2 match (or 4 for that matter...) thats all part of breaking a motor in... as for a builder using out of spec stuff, well thats all up to the costomer. some people cant afford New housings, OR, their housings still have life yet in them.. even so, Brand new EVERYTHING, will still give you a low cranking pressure, not every peice (seals/housings) are machined precicly perfect to one another. Untill its broken in, and even then, I would'nt trust anything but a Mazda spec compression tester. Simple test to prove what I am saying.. test your pressure with 24 volts or more! get that sucker spinning, you will see, it goes up! Trust me! It will!

Schnide

If cranking comp had no meaning it wouldn't be listed as a specification to check to indicate engine condition.

although the compression numbers will vary with altitude and if the starter is not functioning at full strength and if the Mazda compression reader is not used there is another thing that can cause a normally healthy engine to differ from specs.

all I'm saying is completely ignoring specs set by the factory engineers is not an entirely wise course of action.

jreynish

iTrader: (2)

alright how did my name get into this thread,
my take in sealing and cold cranking compression (no impact or affiliation against or with Rx-7 specialties)
all though centrifugal force will increase sealing capability a little with the added force a metal on metal seal is only as good as the two mating surfaces, if an engine cranks at 288 +/- RPM and pushes 100 psi on all faces then at 2000 rpm it might Push 150 psi
but and engine wich pushes 60 psi on all faces the at 2000rpm might push 110-120 psi.
these numbers aren't "hard" but just an example to get my point accross if you have a bad matching seal and housing then that is going to lower compression, and if you do and simply have weak springs then yes compression will be better at speed due to centrifugal force than it would be at cranking speed.
There are simply too many variables...
but in the end YES I do think cold cranking makes a huge difference in the final result low comp at crank lower comp at speed vs an engine with high comp at crank will = higher comp at speed relatively. But as ChrisNG said he will see... i personally look forward to seeing what he comes up with for numbers with a healthier engine. As has been said Mazda did it for a reason... they tend not to put those kind of numbers out there arbitrairily... they are usually derived from "many" tests... and research.. etc.. I choose to listen to the people that designed the engine rather than a person who merely puts them back together again. (regardless of who that person is)

Maxthe7man

Its not all centrifugal force, mazda indicates the greatest force for providing seal is gas pressure within the motor, and is also related to cranking speed, the lower the rpm, the more time there is for gas which gets underneath the seal to load it against the wall to leak out and reduce loading pressure, turn any motor slowly and you can hear the compression leaking slowly through every clearance, the greater the clearance the more pressure leaks, the faster you turn the engine, the less time you give for the gases to leak, and thats the tester has a rpm chart on it, to set a time standard for leakage rate, there is more time for chamber leakage at 200 rpm then there is at 250 rpm, so of course the readings at a lower speed will be lower.
If a motor makes 60 psi and thats all at 250 rpm, its leaking alot of its gases somewhere compared to a motor that makes 100 psi..That motor will be harder to start, more prone to flooding, and its BSFC increases substantially over a motor that makes 100 psi..
The other week I saw the difference from a 60 psi motor to 100 psi motor, end result was nearly 100 rwhp, in the same car, thats power thats build directly into the motor, ChrisNg, Black 93FD and myself have one thing in common, we all have had a famous 60 psi motor, and funnily enough regardless of turbo size we all end up at nearly the same hp level, that tells me that a 60 psi motor will only hold so much combustion pressure , enough to make between 365-388 rwhp, and no matter how much boost and fuel you throw at it, it will always end up at those levels. There is also a density correction factor for altitude from mazda, it makes sense if you start with less absolute pressure overall the compressed pressure will be less as well.. At our altitude in Calgary it ends up movin the MIN spec down to something like 76 psi or something like that, and thats a min spec not a middle of the road operating spec.
How important is compression pressure in the end, look at the mazda fsm diagnosis chart, low compression shows up as a contirbutor to alot of faults and they arent high speed faults. Its especially important with stock ecu cars that are expecting certain things to happen in certain times, with in certain parameters, if you have to do any kind of emissions test compression becomes vitally important. Max

offrotor2

I never did say that cranking comp had no meaning it... Just trying to make a simple point here!

black93RX7

Chris NG: I am really looking forward to seeing your numbers once your new motor is in. There is a good chance I will be rebuilding my motor next fall. I will change nothing else in my setup in order to gauge the difference between a low compression motor and a normal compression motor.

Assuming of course I can build the motor with normal compression

Maxthe7man: you made some really good points, do you still have the low compression motor in your car?

Maxthe7man

Nah, it let go on the dyno, go figure.....Max

RX7specialties

This thread started concerning my apex seals!I am not going to defend the quality of our product. In fact..I don't even want to discuss the seals or my engines. I'll start by saying that "you are all correct"! Why? Because there are gains and losses to each seal! I am ?? to see that there has been no debate reguarding the strength issue! Just as a 4X4 is stronger than a 2X4, a 3mm has more structural mass than a 2mm and is factually stronger!
I fully support the testimonial from Rotary Resurection! If one wants to argue the strength...
its just plain stupid! There is a simple reason why engineers like Fracesco Ianetti offers 2 & 3 mm. He designed, perfected, and sells an amazing product and is NOT a Mazda engineer!
Mazda engineers have been admirably referred to in this thread...yet Mazda engineers were the ones responsible for designing and implimenting the 3pc. seal which destroyed the Rotary engine and its reputation scince 1986! The old 12a's and 13b's used to see over 300,000k. On average, the 86-95 engines are lucky to see 200,000 at best. When the engineers refer to compression specs. in the book(90psi)...it is a reference! To say that an eng is "worn out" at 75psi. is rediculous! The old 12a's used to run well with worn out rotor hsngs. and 50psi cranking. To the average owner, the power losses were barely noticable...
more in gas milage. What many of you may not know is that testing the compression is only verifying the seals/hsngs. in the compression location of the cycle. There are a large % of engines that read good comp. yet run poorly. The most common spot for wear on the rotor hsng. is at the intake and exhaust areas. This will cause the exhaust gases to leak into the intake cycle causing reversion (hence low man. vaccum) This is a critical area, in some cases, more so than the comp. area. Speaking of leakage..Max is absolutely right! The
"TIME" factor is HUGE! By the time the air/fuel has maximized based on the volumetric efficency of the combustion chamber, the gases will start to escape at this point! At higher RPM the gasses are Quickly exhausting through the exhaust port. One way to show this leakage does not heavily effect the overall performance is to check out the data on the RX8
engine.The Rennesis eng. uses a .0025 end gap as compared to .0002-.0003 (factory) This gap has a purpose..however, it does not ruin the overall performance of the engine based on high RPM...but the bottom eng SUCKS! Another example of a good 2mm application relative to "TIME" is our expander engine project which you can see pics of in the "Non automotive applications" section of our website. The rotor hsngs. are RX8 with no Ex. port.
we made our own port at the lead spark location as the engine uses hot gases under constant pressure to drive the rotors/shaft @ 3600rpm. Scince the "TIME" is longer based on rpm and especially the long duration of the power stroke. Again, 2mm all the way. The higher the RPM and the shorter the TIME, losses of using a 3mm becomes less! I know that 2mm seals will "Crank" higher #'s than 3mm. And at lower rpm, 2mm's make the down low power feel crisper and slightly stronger. As far as the centrifugal factor...any seal increases approx. 4 fold per 1000rpm. The 3mm's also benefit by the other thing Max said(combustion pressure beneath the seal)...more surface area exposure to the seal...more pressure!Whereas the 2mm's gain from less surface area contact to the rotor hsng. There are other factors when measuring compression #'s. Carbon (HUGE)! as the springs have a tougher time doing their job. Side hsng. wear (HUGE)..and it doesn't mean that the side seals and hsngs. are going to seal well all the way throughout the cycle.High or low comp. is not debateable just because of the apex seal size! The biggest concern to attribute to poor sealing at the apex seals and weak engines is compression differential (uneven readings)
And this applies to 2mm and 3mm the same. We use 2mm in 95% of our NT eng's. The reason I choose 3mm in high boost/HP builds is for STRENGTH! And we do build 2mm turbo engs. just like the decision we made with BBMAC today! The 93 engine mentioned in this thread has brand new rotor hsng's, lapped side hsngs. and all brand new seals...if the engine cranks at 60psi...so be it! It makes good power and so do alot of 3mm 12a's. The bottom line...both 2mm and 3mm will handle combustion pressure. Tuning is critical...but injectors fail...plug wires fail...hot spots cause preignition, and bad gas sucks! If you want X-tra insurance..go 3mm. Just ask the pro drag racers and don't say they don't know what their doing! Sincerely, Adam Heyman