13b4me

Spider steel apex seals...

drago86

If by new you mean a couple thousand years old. Wootz is what middle eastern/indian swords were made of. Awesome for swords but modern steels are much more suited for apex seals. Why does everyone seem to be trying to "solve" the apex seal "problem" with whatever particular material is "magic" in their minds? If you made the seals any stronger the rotors would just start denting from the detonation. Tuning is the answer to the precieved apex seal problem, not super alloys/rare gems/ ancient sword forging techniques/etc.

Tofuball

Dude, follow the link. It's helarious.

I personally know that diamond isnt a metal :P

ShadowX

How to make the metal Damascus steel was recently 'rediscovered' , or something very close...that's what I was refering to, there's a reference in the wikipedia about it -> http://en.wikipedia.org/wiki/Wootz_steel

If you're magic material comment was directed to me, you must have missed my reference to OEM seals taking the abuse. The OEM seals can take detonation up to a point just fine, they're not as fragile as most think. But if you think that there's not a better design out there, that's silly. It's not likely that a better design will be 'discovered' in forum discussions, but you can't insult someone for simply asking.

The 787B used 2mm ceramic seals, so obviously the OEM seals aren't the best solution for all applications.

Valkyrie

Teflon is good for what, 500+ degrees farenheight, right?

I wonder why you couldn't take a very strong but harsh metal like those in Rotary Aviation seals (which are known for being tough but hard on the housings) and maybe put a strip of telflon down the middle, or a teflon coating all around the seal (precision machined of course)... that way you'd prevent wear on EVERYTHING, even the rotor's seal grooves.

...but just how hot is the combustion chamber? Assuming the engine is at an operating temp of 180 or so...

I would think it's at least cooler than a piston engine since it doesn't "sh*t where it eats."

dopefishlives

Actually combustion temperatures are HIGHER in rotaries than in piston engines.

Kenku

Well, exhaust gas temperatures are in the neighborhood of 1600-1800 degrees, so peak temps at the combustion chamber are going to be a bit higher.

So, teflon's not going to work so well.

ShadowX

cooler? The EGT's on my TII after starting are in to 400C-500C range, getting up around 800C when I'm boosting. Teflon wouldn't last at idle...that's why there's ceramic coatings!

Kyrasis6

Detonation in any combustion engine is going to make it short lived so like said trying to design an apex seal to withstand it is pointless.

I think most people want the longevity of piston rings from their apex seals.

Matt Hey

I disagree to a degree. Yes, severe enough detonation and or often enough detonation will make any engine short lived but it is possible to make a tougher apex seal that will hold up to more abuse including some detonation. The apex seals live in a very hostile environment where they can crack or chip without even much abuse. Making them tougher, instead of as hard, would make them resist cracking and chipping but may increase the chances of them warping (better than chipping or cracking IMO) and likely would give up some wear resistance. The stock apex seals have too much wear resistance and not enough crack/chip resistance as most crack or chip before they wear out. I'm not the first person to buy the latest aftermarket apex seals and I believe the OEM apex seals are pretty good but manufacturers have to make compromises for production and I do believe a better apex seal can and probably already has been developed at least for some applications. There is an apex seal already that is guarenteed not to break in the engine...

http://www.performancetestedseals.com

GUITARJUNKIE28

PTS seals better than any other seal in the market place therefore create more horse power and more combustion temperature. You will be required to use more fuel to achieve a better burn and quench combustion temperatures. Do not forget, more fuel, more horsepower.

These seals do not wear the housings or rotors.



...i dunno about all that.

rx7vadim

so how do you know for sure that abel uses stock seals?

RETed

Sure.
You make the apex seal "tougher", and this usually ends up eating the rotor housing and / or the rotor apex seal grooves themselves.


Define "very hostile"?
You should not be trying to build a seal to withstand detonation - you should be tuning to AVOID detonation.
Keep detonation in check, and the design of the apex seal become a lot simpler.


What does "tougher" mean to you?
Resistance to damage usually means "harder".
Tensile strength?
That usually means "harder".
Compression strength?
That usually means "harder".
If you go opposite of "harder", then you mean more "elastic".
More elastic usually means more chances of warping.
"Less wear resistance" usually means "harder".



How do you know this?
How many test samples have you done?
Do you even know how hard the stock OEM Mazda apex seals are?
How much harder do you want them to be?


I have NEVER used an aftermarket apex seal in my engines.
I have been through all the bullshit from...
Hurley
Rotary Aviation (what are they up to now - 5th generation?)
Atkins
I used to criticize all those aftermarket seals when they first came out when people were raging about them - look at them now...
I can't afford any of those overpriced exotics that costs several times more than the stock OEM Mazda apex seals.
I've stuck with stock OEM Mazda, and they have worked fine for me.
In fact, I have accidently cause my engine to ping (hammer on metal) hard a several occasions on a new set of *3-piece* stock OEM Mazda apex seals with no failure.
I don't believe anyone has come up with an apex seal design that gives you the performance the stock OEM Mazda apex seal, period, for the money.
Sure, there are harder and more expensive...

Oh, I don't believe any hype from "racing" use.
Race engines get torn down regularly in between races.
To me, this is not a true test of how "streetable" those seals are.
Give me evidence of how well those seals do in a 100,000 mile longevity test, and then I'll look at the results.

Oh, BTW, as for the original thread subject...
Tungsten is a bad choice.
It's too heavy - requiring extra heavy springs to keep them in place.
It's too abrasive - it'll cause havoc where it contacts the rotor housing and the rotor apex seal grooves.
It's too dense - it's going to increase clearances in the rotor apex seal grooves due to it knocking back and forth in the slot.
It's almost as smart as the other suggestion of using depleted uranium...


-Ted

TonyD89

iTrader: (10)

Ted. I am sure you know way more than I about factory seal longevity. And I believe you and I respect your opinion. And I believe you are so right on the Tungston. I do not want to contridict you. Just to help inform.

"Toughness" is defined as "Resistance to deformation". Pretty much the opposite of:

"Hardness" defined as " Resistance to penetration" Wear is the "Penetration of small irregularities in the mating surface "hard surface" pulling small pieces of the softer away.

Smooth depends on the size of your magnifying glass.

Tensil strength almost always goes up with hardness. Which, to a certain degree, can increase toughness. But quickly curves back over to become "brittle" and less tough.

When dealing with steels, it's a balancing act.

Ceramics are very hard and brittle. They make good cutting tools under the right conditions. One has to wonder what happens when that thin layer of oil disappears.

Chrome gets good wear resistance from it's low coefficient of friction. Which drops even more with a thin layer of oil.

I guess it is all a balancing act in the end. But I have to give credit to the people who are trying to walk the beam.

RETed

No problem.

I've heard of:
Tensile strength
Compressive strength
Hardness
Elasticity

This is the first time I heard of "toughness" when talking about metals.
Thanx for the clarification!


-Ted

drago86

We shall make a new term to be aplied only when talking about apex seals for the good of the rotary community then.


Toughness = Fatigue Strength x Fracture Toughness x Yield strength/1.3 (2.6 for calculations done by piston engine propenents)