dubrc

Im tearing down my block this weekend, and I think Im going to go with 3mm seals if I can get my rotors done locally. Anyone in Ontario machine rotors? much thanks

Paul

IAN

iTrader: (3)

Not sure who can do it but why? Is your stock rotors out of tolerance?

You could call Dave at Mazdee's to see. He might know someone.

1-905-619-8813

Ian

dubrc

thanks

Sponge Bob Square Pants

I was also wondering why?

jreynish

iTrader: (2)

it is my understanding that for it to be "milled" properly for 3mm apex seals then you would have to blueprint each rotor.
Also with 3mm apex seals you are adding 150% rotating mass, increasing wear of both the seal and the housings!
Mazda rotors have a hardned part of the rotor grouve stock! when you mill the rotors for 3mm then you are removing the most of that hardned material!
But then again, simply food for thaught

Fingers

Adding 150% rotating mass? Yes, 150% of 2 ounce combined weight of the six apex seals.

jreynish

iTrader: (2)

rotational mass increases exponentionally with radius. It doesn't seem like such a huge difference but think of it, how many times will that apex seal rotate arround the same place? That is alot to add just that little bit of weight that many more times. I could be wrong but that is my take on it. From what I know from rotational physics that would seem to fit.

Fingers

Rotational mass of a 3gram per corner change at the apex of a 900gram rotor means facking squat.

If you're going to be using the rotational physics argument, at least stop squeezing it out of your ***. Take the actual measurements of the rotor, and the center of rotation, and figure it out.

Besides, if it's rotational mass, the other two sides would counterbalance the one apex seal in question.

The difference would NOT be significant enough to notice, nor significant enough to cause slow throttle response.

jreynish

iTrader: (2)

it is not the mass of the rotor, I am arguing it is the mass of the actual apex seal! the apex seal isn't attached to the rotor, if it wasn't for the rotor housing the apex seals would simply fly out.
The apex seal is what causes the extra wear. But you are most likely right! that it is insignificant. However There was a reason mazda didn't make them 3mm, do you increase the thickness of piston rings when you run more boost?

Offrotor

Ed's a mechanical engineer.

Jrey's a physist.

Common knowledge...

Offrotor

what about the 12a? 3mm stock!

Offrotor

whats 1mm in this BIG Beautiful Country of ours anyhow??

hotty

I personally like the 2mm's.. I will be the first to admit I dont know all the pro's and cons, but from what I have seen.. 2mm is better.. besides.. jeff is right.. there is hardened material on the rotor's and I would keep it on my rotors ..
Offrotor.. couldn;t you have combined all 3 of those posts into 1? Is that too hard?
Daryl

IAN

iTrader: (3)

3mm seals = Junk rotors that need to be machined saving grace from book ends!

Or you might be tuning and expect pinging!

blkrx7

>you increase the thickness of piston rings when you >run more boost?

<cough> Sometimes, and you might change the number of rings, the material, or increase the thickness of the ring-lands. None of which really applies to a Rotary here...



There are a thousand pro's and con's to 3mm seals, none of which were asked for by the original poster.

No reason to turn a simple question into another one of 50 debates on the topic. A simple "ensure your doing it for the right reasons, and here are a list of companies that do it" would probably suffice. You might even throw in a good beat-the-guy with 'use the search button' stick for good measure.

(not directed at anyone in particular)

Paul

Edit: Speeeling!

dubrc

well it looks like I opened up quite the can of worms. I know there are various pros and cons to the 3mm seals, but that is why im looking for someone who does it, as they'd be the best to ask. 2nd, I'll be tearing my block apart this weekend, so I don't know what shape the rotors are in yet (already have some book ends, a candle holder and other rotor turned decor stuff )

--Paul

gambone

iTrader: (3)

I went to that big lake and took a **** and didn't stand back fare enough. I've been dicking with these motors since when most of you all where born, I hear this and that and it goes on and on. So I came up with a few rules 1, I don't hear from thoes that don't do

Offrotor

hotty...(I dont feel comfortable calling you that but oh-well)

I posted 3 times cause a had few thoughts one after another...? never had that happen to you???? Let it up on me dude... hursh it down a bit.....

jreynish

iTrader: (2)

offrotor incase you didn't know (simply for information) actually I am in engineering, not physics.
also there is an edit button on the bottom right hand side of your posts, third from the right, click on that it will allow you to ammend or add things, as long as they are withing 15 mins of initial post time.

deggial

but maybe they will try to sell you on the idea, simply for profit. Best to do some research first, so you can ask intelligent questions, and hopefully get intelligent answers

Sponge Bob Square Pants

Don't trust any rotary shop that can machine the rotors for 3mm seals. Just because they can do it doesn't mean they can do it properly! You do not want to risk ruining a great engine by not shopping around and asking questions.

A good place to start might be Pineapple Racing.
They promote 3mm seals, and are also one of the more respected shops in North America.
www.pineappleracing.com

I know RX-7 Specialties also machines their's in-house. I haven't had work done there, or talked to anyone who had rotors machined so I cannot comment on it.
I was told that Ari at Rotary Performance (www.rx7.com) thought that Adam's milling jig for rotors worked pretty good. This is just hearsay though, so don't live by it.

You should still go 2mm, but that's not the question here

Aaron Cake

iTrader: (1)

Well, any machine shop worth being called a machine shop will be able to do it....

chris_stampe

Is that a fact? How exactly is it done?

HUGH

I have heard the same thing. I have also had my engine be the proud recipient of RX-7 Specialties 3 mm apex seals. I dynoed at manifold pressure (7 psi?) @ 269rwhp on a DYNOJET 248 CHASSIS DYNAMOMETER with supporting mods but no turbo upgrades. I am sure that the 3 mm apes seals is responsible for me not getting 270rwhp...than again I could just turn up the boost.

rx7_turbo2

None of the rotors I've seen milled for 3mm have been done properly. Now granted it's only 3 or 4 sets of rotors, but not a single one was correct. All of them were milled using a jig that milled them to one side instead of down the middle. In addition some of them were not even milled straight, they had a nice big "wave" in them. Some pictures were posted up, doing a search should find them. Only two of the sets I've seen were done by RX-7 Specialties. Not sure who did the others. None the less the 100% screw up rate I've seen was enough to totally turn me off 3mm seals.

I run 2mm stock seals. Mazda has a hell of alot more money in and for R&D than any of us do, and they use 2mm. And they have warranty claims to think about. If 3mm made a more detonation proof and more reliable motor Mazda would be the first one's running them. And they are not, that speaks volumes in my opinion. No one has ever come out and revealed the science behind why 3mm is stronger. All we ever get is "There thicker moron, that makes them stronger, I've been building motors since you were in diapers" There are WAY to many variables to make a blanket statement like that.

As far as I'm concerned and once again it's just my simple minded opinion but... 3mm seals are great for builders who want to use damaged rotors no longer good for 2mm, and make a few extra bucks.