I was wondering how you can tell if you have 3mm apex seals done on your car, i had a engine replacment done at 100000 in 1999, by mazda canada, did the have 3mm apex seals done?? what is the advantage of having 3mm apex seals??

 

Unlike the 2mm's when you detonate, you won't be as likely to break an apex seal. It's not necessary unless your a pretty serious racer.

 

Are they that much more expensive? What about the carbon over stock? Is it worth beefing them up at all during a rebuild, even if it is just a daily driver occasional road racer.

 

well they require machining of the rotors...so that can add to the cost of going with 3mm 's..but if you are out of spec for 2mm's..then it can SAVE you money...they stand up SLIGHTY better to detonation...but not much more...the rotary must be tuned well...regardless

 

Thanks johnny. By the way, your not a customimport dude are you? Also, aren't the carbon ones really expensive?

 

customimport ???what does that mean...

yes carbon is expensive...if I was to get new seals I'd go for those ones from Hurley...they great thing about those is that they can be softer...so if one get shot...it's less likely to take your housings with it...housings are expensive....

 

Don't get stock. Just get the Hurley Racing seals. They are the best bang for the buck. The 3mm's are the same price as the 2mm's...bout $350-400, but to grind the rotor's to 3mm is about another $300.

 

Nothing johnny, just took a chance. Thought you might be someone I know, through the 'net.
Thanks ernieT. Just curious because I'm sure I'll be faced with that decision one day. Hopefully a long long time from now. If I can get my ECU, that is.

 

Machining the rotors is really tricky stuff. If they are not done perfectly for the 3 mm - kaboom! My personal opinion is that they are extremely hard to do, even for a skilled operator. I would opt for new rotors and stick with 2mm, even though they are outrageously expensive. Clearance is everything on a rotary. Very few FD3S rebuilds require new rotors though......

 

I will tell you one disadvantage, you make less power with 2mm compared to 3mm...This is why Mazda do not use them in their engines for over 15 years !

 

2mm makes more power than 3mm, It is to do with better sealing and reduced friction losses.

Take two identical engines side by side and you will see a power increase in the 2mm apex engine v's the 3mm one....it makes sence when you think about it.

 

I'll buy that, after all, Mazda has reduced the size of the apex seals over the years with each new version of the rotary.

 

very interesting, I never thought about the extra friction coming from the upgraded 3 mm seals. Good point