Well I blew my engine about a week ago, and recently got it apart. I broke off a piece of apex seal in my front rotor, most likely from some preignition. This was at 14-15psi mind you. I plan on just running 12psi whenever I get the motor rebuilt. So now I have to decide on either the 2mm or 3mm apex seals. I'd like to just keep the 2mm seals in there, but for reliability reasons I am leaning towards the 3mm apex seals.

Are 3mm seals really worth it? Or should I be just fine with the 2mm seals from Rotary Aviation? Or should I go some other route?

Thanks

 

just go with good 2 mm... 3mm are more "tuner friendly" but they dont seal as well...

 

There will be no more tuning, but I would like the engine to be able to take some knock if it some how happens again. I'm still not sure why it knocked this time.

 

its because your car hates you Brian. Lol. I'd also like to know the difference between 2mm and 3mm seals.

 

I was going to go with 3mm, but I believe your rotors have to be machined... that's more money, and I'm not going to be trying to run 30psi of boost so I really don't care haha.

--Gary

 

2MM should be more the able to handle 12PSI, especially the RA seals from what i've read. My plans are to run S5NA rotors with a turbo between 10-12PSI...but that won't be done until the summer I think.

 

^ DAMN! with the n/a rotors, that will be alot of hp and compression. I have a feeling you'll find you can only do 10 max before you start having detonation problems.

 

We'll see!

 

I've been running 15 psi for 3 years now with stock 2mm seals. I would rather do that then have good rotors re-machined to accept 3mm.

 

There is a believable case made by rotary aviation that their 2mm seals are significantly stronger than stock Mazda 2mm seals when it comes to the brittle factor. They put a write up on their site about the metallurgy research that went into selecting the alloy for the RA seals, and it's not ferrous based (that's all they will say for proprietary resons).

I've had 2mm RA seals in my ported NA for a year now, and they have about 8k miles of high revving driving with premix on them. They look great. I've had them out a few times for side seal repairs, and they still measure up at 2 thou seal/gap clearance and show good round sealing edges. In any event, current RA seals are a different animal than old ones when it comes to the heat induced warpage problem that early ones had, traceable back to a contractor that fed the seals through the milling machine too quickly. Apparently the early seals got some heat related internal stresses induced on them by this manufacturer, which is no longer milling seals for RA.

I'd go with the 2mm seals and some water injection. WI changes the combustion properties in a postive way relative to the volatility of the combustion mix, effectively raising the octane and resisting preignition.

 

I understand a lot of people run high boost on 2mm seals, but my engine has blown apex seals twice now at 14-15psi. ( Once on previous owner, once on me) Will 3mm seals be able to take some preignition, or is it about the same as 2mm seals?

 

Can
You
Mill
Your
Rotors
Properly
For
The
3mm
Apex
Seals?

-Ted

 

I hope you don't mind me asking you a couple of questions not related to the post.

-Who tuned your E6K? and How long did the engine last after tunning?

I am kind of going thru this process....

 

This doesn't sound like its the fault of the seals...

 

I had 3mm ra seals in my rebuild and Kevin Landers couldn't get them to seal up, so I went with mazda 3mm. RA's website says to use them with new housings, so be warned.

 

especially because is the front rotor.... the rear seems to be the problem child, thoretically due to cooling issues.

I'd be looking into the injection system.

ALSO, you need to get a FRESH 2mm seal and clean the rotor grooves of EVERY little speck of carbon and then test the seals for clearance, top to bottom. You can't use an old seal to do this, it must be a new one.

The seals can wobble back and forth in their grooves and wear the groove into a "V" shape at the top. Even with new seals, if the grooves are out of tollerance, they will eventually break again. If the grooves are out of spec, then you will HAVE to go to 3mm Seals or get new rotors.

However, Zkeller had 3mm seals in his 500HP car and blew them up just as fast as he blew up the 2mm seals. He has since switched back to 2mm Seals, added a BIG ASSED FMIC, an Autronic ECU and 20 LBS of boost, and hasn't had a blip! Plus the 2mm seals give a much better idle as they have better compression at low RPM's

 

Previous owner tuned it, and the motor lasted around 10k. I'm sure it could have lasted longer.

I don't really want to get into EMS tuning, so I'm not going to. I'm most likely going to just get the RA 2mm seals, and run 12psi max. Still will be fast enough for me.

And Ted, please don't fill up space unless you are going to be constructive.

 

If you did a proper search, you wouldn't NEED to waste space with this thread.

You want something constructive?

3mm apex seals will give you a SLIGHT more safety buffer against detonation, but any serious detonation will kill the motor.

The problem with most 3mm apex seal install is the precision milling of the apex seal groove on the rotors.
If the apex seal groove is not totally perpendicular and / or not given proper clearances, this causes less compression and / or weaker against detonation versus a stock 2mm apex seal rebuild.

Bottom line, it's not worth it in most applications.

Stock 2mm apex seals have been proven up to 500hp levels.
I bet you're not even coming close to this kinda power levels, right?
If so, the rebuilds are bad, and / or the tuning is causing the engine failures.


-Ted

 

Owned

 

This is a commonly stated con of 3mm seals, but it's largely untrue. The only real reason they dont seal as well as stock seals is because they're all 2pc instead of the old 2mm 3pc design which seals perfectly. The 2pc 2mm seals perform the same as the 3mm 2pc. I have the 3mm's in my FD and that engine is making 125-130psi warm. I've never seen a 2mm seal engine, even with 3pc seals, do any better than that. As far as real world sealing/running difference, there isnt much between them.

Keep in mind mazda used 3mm seals in all pre-86 rotary engines, and those engines miraculously sealed just fine, until the chrome flaked off the rotorhousings, which is another problem entirely. IN fact, why do you see some of these older engines still floating around with more original mileage than the 86+ engines? Think about it...

As Ted said, the main point is the accessibility of milling. IF it can be done reasonably quickly and properly, then I see no real reason not to do the upgrade. The seals themselves cost basically the same, as do the other parts. IT can't hurt, even if it doesnt help. It could be the difference between another rebuild or a close call. True, if the engine is tuned right there wont ever be a need to find out, but everyone makes mistakes, tuning mistakes are easy to make. Don't go out and spend hundreds of dollars on it though.

 

I believe he was making just over 400 rwhp.. Brian you are an idiot for not turning the boost down before hand..I had no idea Scott blew it at that same boost level that you did. So are you going 2mm now?? When you going to have her back on the road again?

 

Thanks for the response

 

Thanks for the useful information. There are hundreds of threads with '2mm' and '3mm' seals in them, and most all of them are full of BS.

Thanks for the responses guys.

BTW- My car made 408rwhp on a 100degree day with around 100% humidity, so on a nice cool day I'm sure it makes something close to 500hp.

 

.

 

Brian.. you car makes 0 rwhp now. You should dyno it once you set the boost to 12psi.