Resource

I have someone that is going to make me some 2 peice titanium apex seals for pretty cheap.

From what I'm being told they will be stronger and have alot more elasticity than the ceramic seals.

Does anyone know the exact metal type that is used for the stock mazda seals?

680RWHP12A

the stock seal is made from a material called Ferratic. The rotor hsg . is plated with Elsinil. make sure those two metals can work together, wear characteristics, friction, seal chatter, amount of seal lubrication, wear, all depends on the compatabilities of the two metal types..

Manolis_D

iTrader: (2)

I was under impression that Titanium coudln't handle such high temperatures without breaking down. Ti also catches on fire if you get it hot enough, btw

-Manolis

turbostreetfighter

titanium will not work, it is a material that does not take well to abrasion. meaning that if it touches another metal even if the other metal is titanium it will gaul, trust me i have been a machinist for more than 15 years and have machined tons of titanium and it is VERY abrasive on tooling. you would not even be able to get the engine started before it would lock up and ruin your housings.

have you seen what the domestic scene has to do when they run titanium rods?? they have to have special rod bearings made to keep the rods from touching the crank!!
MWW

Resource

Rock on, this is the info I needed. It was just an idea

Thanks.

drago86

Just something to try: coat them with keronite, or another ceramic coating like it that doesnt change the surface dimensions

680RWHP12A

turbostreetfighter
in your opinion what would be the ultimate seal material? by this i mean for a high revving, high hp best sealing extremly hard to break, dont care if it dosnt last long type seal? other people, if you have input too please, im curious????,,,...

karism

A guy i know made Titanium apex seals (2 piece).
His engine isnt quite finished yet,but he recons that its going to work.
I think the problem(among others) is that the clearance has to be so much bigger,seeing that it expands 1 3/4 times as much as the normal steel seels would.So the clearances have to be real big.How will it start up ??

We all told the guy it would work,but he insisted.I`ll keep you guys updated.

jeff48

turbostreetfighter is right.

The gauling characteristics of titanium are very well documented. At the 2002 Road Atlanta Petite LeMans I had the titanium conversation with the head tech for Yojiro Terada, Jim Downing and Stephane Daoudi's 4 rotor LMP 675. I wanted his suggestions about apex seal materials and I was particularly interested in his ideas about titanium. He told me in no uncertain terms that Ianetti ceramics are all he will use and that the gauling properties of titanium made it a bad choice.

Best advice, leave the titanium where it belongs, in jets and paint.

93tourtom

Using Titanium would be a very bad idea. Titanium is very bad from a gauling "scuffing" perspective. You could use titanium for it's strength and weight properties if you used a wear coating. Unfortunately once you wore through the coating your engine would be toast. I believe what Mazda uses is a chilled cast iron material which is very brittle. Based on what is used on top compression piston rings, either a ductile iron or alloy steel would probably be the best choice. Use of a coating is also probably needed. In piston engine, either chrome plating or a Molybdenum based thermal spray are used. I don't think chrome would work in this situation since the housing is Cr plated. Another good option would be nitrided stainless steel (440B alloy), which is also a good top piston ring. The only problem with the stainless is it becomes fairly brittle when it's nitrided. Probably less brittle than the stock apex seal. Just my humble opinion.

P.S. My job is as a materials engineer to design coatings for piston rings.

turbostreetfighter

i know it has been said a million times but the OEM 3pc seals are the best bang for the buck, ceramic might be better but i have not tried them yet. i run Mazda's in my engine and have had nothing but good luck with them!!

MWW

Scalliwag

I would not mind trying titanium with my resurfaced housing. I have not read anything about it expanding that much under heat.
Since they use it on end mills and drill bits I am really confused because from what everyone here described it does not seem like a good choice for that.

On my housings I would not rule out seals that may not work well with stock housings. I want something that has the best chance of not breaking. I am hoping that since they have a better coeffecient of friction that it will give me a wider range of materials to use.
In other words I want to boost the holy **** out of a motor and find an apex seal that will withstand it.

Resource

2mm or 3mm ?

93tourtom

The coating primarily used on tools is Titanium Nitride (TiN). Which is a thin ceramic coating very different from titanium metal.

SPOautos

I know this might be asking to much and if you dont want to share I understand BUT....

What size Mazda seal are your running? Also, do you run the oem springs???

Are all the 2mm 3pc seals the same no matter what model rx7 they are for?

Thanks,
STEPHEN

Scalliwag

Hmmm so I wonder what would be a good candidate for a really strong seal? The lower the expansion, higher temp, a lowest elasticity the better.
I wonder if there is a grade of stainless that fits the bill?
I have heard of really hard seals that were tried during development that tore the hell out of the housings but I never heard what the materials were.
I would love to put my housings to the test with something like that.
I would just keep cranking the boost until something gave way! R&D on that could be alot of fun!

peejay

Yep. There is only one 2mm seal made by Mazda.

Scalliwag

Here is a great site for finding out whatever you want to know about metals and alloys http://www.asminternational.org

turbostreetfighter

i see that this is going to turn into a seal thread, but i use OEM 2mm 2pc apex seals, springs , side seals,corner seals, gaskets sets and bearings. detonation is the enemy and even if you find a seal that can take detonation, the next weak link is the bearings as you will knock them into oblivion if you keep banging on them!! Folks it has been proven that the Mazda seals can withstand up to 1200 h.p. w/o detonation but only 200 h.p. detonating. basically you can use any seal you want but if you detonate, even the almighty 3mm will eventually break. i will say that the sealing properties of the 3pc unit is far superior over the 1 or 2 pc seals. especially at the lower RPM's. a good idea would be to make a 3pc 3mm seal.

oh yeah, Scalli the TiCn coating on tools is not the same as pure titanium. that coating is used on top of Cobalt tool steel to increase wear characteristics. that being said i dont think you would have an advantage of using TiCn on seals because seal dont have a wear problem.


MWW

MWW

Resource

Damn you detonation!

nimrodTT

Ferratic I've heard of, but what's Elsinil? And where did you find that information?

680RWHP12A

A Really old Mazda book i read 12 yrs ago.....I dont remember who wrote it or what it was called, but I got it from the Cal State Northridge Library, and I BET its still there if you search for any books about the "Wankel Engine"....so if you happen to be in the area......

ronny76

You could also try to make the apexseals of beryllium,if you are able to get it.

Scalliwag

I did some research on Stellite 6 and everything about it looks really good except for the price The tensile strength (point of pressure it breaks at) is twice as high as the higher strength stainless steels. The yield strength (point at which it starts to flex) is the same. That means the **** does not bend but that does not matter. Bending or flexing is almost as bad as breaking in our application.
It is used in a lot of pumps and is supposed to have a really good coefficient of friction. The price is spooking me though. No solid numbers but the examples did not look good.
Here is the description from their website:
"Stellite 6 is the most widely used cobalt base alloy and exhibits good all-round performance. It has excellent resistance to many forms of mechanical and chemical degradation over a wide temperature range, and retains a reasonable level of hardness up to above 800°C (1470°F). Particular attributes are its outstanding self-mated anti-galling properties (which result in its wide use as a valve seat material), its high temperature hardness, and a high resistance to impact and cavitation erosion. The alloy is ideally suited to a variety of hardfacing processes. It has less tendency to crack than Stellite 12 in multiple layers, but is more wear resistant in abrasion and metal-to-metal or galling conditions. It can be turned with carbide tooling. Stellite 6 is used on valve seats and gates; pump shafts and bearings, erosion shields and rolling couples. It is often used self-mated. "

drago86

Beryllium is VERY brittle, which is why they mix it with 60% aluminum to get AlBeMET which was used in F1 racing engines. Beryllium, also i believe beryllium galls rather easy (unsure) and is INCREDIBLY toxic to about 50% of the population. It is also EXTERMLY costly. AlBeMET would be the absolutly perfect metal to make a rotor out of however,....mmm,.. 2.5 pound rotor... of course ceramic metal matrix materials are just as good. Aeromet 100 would probably make a good seal although it too is very expencive. Titanium would only work if it was coated with a coating like keronite, and even then, as soon as the coating wore through, the seals are scrap, and you would still have the problem of Ti's high expansion rate. People seem to try and throw titanium at everything, while it does have some very nice properties, it does have many downfalls that make it not sutible to many applications, especially a wear iteam like a seal. You want something very hard, like ceramic to prevent wear, with a good friction coeficent, again like ceramic, with as little expansion as possible, like ceramic,a ver light material to keep it from floating, like the carbon aluminum seals, or ceramic seals, and springy enough to withstand detonation, like some steels. Ceramic seals are the ultimate seal in everything but a detonating motor. If its detonation resistance your after try aeromet 100 or another "super" steel. The only real problems with this are cost, and seal weight, which wouldnt be an issue if you observed the stock redline for 2mm iron seals approx 8500 rpm or 3mm at approx 7000