jpre

I tried searching a bit, but didn't find anything related.

Max7

Why? you rebuilding? curious? 12A? 13B? 20B? Turbo? N/A? going for 200HP or 600HP?
try over in the Rotary Performance and Single Turbo section, this has been covered many times, and it still goes on. there is no perfect answer.

jpre

Oh, now I see why my search wasn't as successful as it should have been. I believe I was only searching the 1st gen forum. I'm not rebuilding. I guess I was curious as to why 3mm were used in SE's and not 2nd or 3rd gens, or if engine specific, N/A 13B stock 130hp then.

lemonade

3mm are obviously stronger, but i think at high rpm they dont work as well...or something

OnlyOnThurs

12A have 3mm as well (i think)

REVHED

2mm seals are slightly more wear and rpm friendly as they are lighter and have less contact area. 3mm seals supposedly offer a bit more protection against detonation hence why they are often used in turbo rebuilds.

REVHED

Yep, 1974-85 engines were 3mm.

1badFB

iTrader: (1)

Well the way I see it, the bigger seals do less damage to the housings as they glide along it, while the smaller 2mm apex seals do a little more damage since they appear to have a sharper skinnier edge. The main difference to the two in my eyes are their weight. I think mazdas idea when they changed to the smaller apex seals was to keep them seated on the housing better at high rpms. I get a picture in my mind of the 3mm seals hopping a little bit more as they go over the little transition (bump) in between the 2 halves of the peanut shaped housing, whereas the 2mm seals keep in contact more as it takes less spring power to push them back down over the little hump. This is all in my head tho so if im not right someone plese correct me.

Siraniko

iTrader: (13)

I have been using 3mm seals for almost 25 years and I never had problems with it. And no, I drive my cars like I stole them. This is on N/A application. turbo?? no on-hand experience here.

steve84GS TII

Stock 2MM seals are PLENTY strong.They are lighter and inflict slightly less friction on the rotor housings.Mazda has,over the years,whittled down the width of their apex seals as newer/better materials and manufacturing preceedures came about.Theres nothing wrong with 3MM seals on a factory/mild engine,they just represent older technology.
The main advantage to 3MM seals, when rebuilding a performance engine is that they are able to absorb more abuse when your tuning to the max and trying to eek out that last bit of HP.... I.E. racing....typically when forced induction is used.For a zingy,high strung N/A engine,Id stick with 2MM,short of carbon seals,like on a bridgeport/PP.
If your going to run a consistant setup and not constantly tweek the boundries of your engines power/tuning,then 2MM seals will be fine.If you build up a 1st gen engine your pretty much stuck with 3MM since there were no 2MM 12A rotors.The SE 13B can be built with 2MM FC rotors,but thats another debate altogether(rotor compression/weight/interference)
I run stock 2MM on my S5 TII engine with 14psi of boost and a streetoport.I was ready to fork out for 3MM seals when John @ Mazdatrix built my engine.His words,"Save your money."
I used the money to help pay for more new parts in the rebuild.In my opinion one of the best things you can do to make a more reliable engine.Nothing like new housings,rotors and seals.

Directfreak

iTrader: (2)

Well said Steve. I too run 2MM seals in my car - well over 400 rwhp and plenty of boost.

Blake

I agree with most of the other comments. 2mm seals are strong enough for just about anything, provided the tuning is perfect. 3mm, while not quite as good at sealing, do offer a bit more margin for error in the tuning department. Guys like Peter Ferrell (PFS) oftentimes get militant about the subject (believe me, Peter once cornered me and gave me an ear-full on the subject for about 15 minutes), claiming 2mm seals are the ONLY way to go, but they are usually expert tuners who don't find any advantage in having a margin for error. Peter also claims 3mm seals chatter, but he's about the only one I know that believes that. Rob Golden has had a lot of success with them, at any rate, and I've never had a problem myself.

So...2mm if you are an experienced tuner or paying one to do the tuning for you, 3mm for mere mortals who might hear a ping or two in the process. Of course, non-turbo cars are best off with 2mm seals, as there is little risk of detonation-induced failure unless you are WAY off on the tuning (ignition timing).

Pele

iTrader: (28)

Hell, don't the RX-8's have 1mm apex seals?

Siraniko

iTrader: (13)

If 2mm is the best one to use, please explain why most people are machining their 86+ rotors to accept a 3mm seals. Im not putting you on a spot but there have been prior debates over this issue and I consider your input very informative.

thanks

Pele

iTrader: (28)

It's been said before. Boost handling and strength against detonation in turbo apps. N/A won't subject the seals to that.

Blake

Who are "most people"? There are only a few possible reasons to machine out 2mm rotors for 3mm seals, that I can think of. (1) Turbo applications, (2) NAs with worn-out apex seal groves, to save the rotors, and (3) NAs running carbon-aluminum seals (rare, in these days with ceramics for racing). What am I missing? Certainly, people don't do it for better sealing and the added strength is only in the detonation department, which is not really an issue for all but the worst NA tuners. The cost of machinging a good set of rotors would be a BIG downpayment on a set of ceramic seals, which are better in every respect -- you can double-spring them like carbon seals, but without increasing wear, so the sealing on the major-axis is better and, hense, gives you significantly more torque. You can even get ceramic seals with a 3mm base, chamfered to 2mm at the sealing edge, which works because they don't wear down. Ceramics are allowed in just about any class, so no one competitive is running anything else.

Siraniko

iTrader: (13)

So for N/A application, which one would you choose.

Directfreak

iTrader: (2)

Whatever the engine came with.

Siraniko

iTrader: (13)

doh! you just earned a cookie.
Well, Im asking as I just never had any problem with 3mm seals from day one on N/A application. Currently, Im contemplating on which seals to use in my next P-Port project.

Siraniko

iTrader: (13)

I would like to apologize to everyone especially to blake. I was bored and I was asking too many stupid questions.

Blake,
If you're planning to attend SS8, I would like to buy you a beer. PM me your # or I will pm you mine.

Thanks

Blake

Not sure what you're apologising for, but I've never turned down a free beer in my life and I don't plan on starting now. I will be at SS8, staying at the Hilton and attending the banquet. Arriving Friday evening and leaving Sunday morning, via John Wayne. Anyone else wishing to buy me a beer can find me in the Hilton lounge prior to and following the banquet. My number is (503) 819-0974.

Siraniko

iTrader: (13)

I was referring to my noob posts. At any rate, I agree with your posts and as I said, I owe you a beer!!! Im not attending the banquet but I will be there on Saturday. I will call you then.