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Apex seal springs with ceramics

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Old Mar 6, 2024 | 05:10 PM
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Apex seal springs with ceramics

In the
Street Rotary book Street Rotary book
it says special springs are needed with ceramic seals because regular springs can wear out quickly pressing against the seal.
If ceramic seals have lower friction than steel, how are they wearing out the springs?
Do the special springs solve that problem completely or are they a wear item? That is, more of a wear item than the ceramic seals.

Last edited by j_tso; Mar 6, 2024 at 05:16 PM.
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Old Mar 6, 2024 | 07:49 PM
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They're probably harder than the springs so the springs become the primary wear item.

I have found, especially with aftermarket iron/steel apex seals, that the apex seal wears fairly rapidly where the spring makes contact.
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Old Mar 6, 2024 | 11:01 PM
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The 3mm NRS ceramic seals I purchased came with springs that appeared to have thick ceramet coating at the tips where they touch the ceramic apex seal.

As for friction and wear.

A low friction interface can be a high wear situation or a low wear situation dependent on the hardness of both materials.

Example of high wear low friction interface would be soft race sintered Carbon/Aluminum apex seals and rotor housing hard chrome surface. The Carbon/Aluminum mixture is soft and wears very quickly despite having low friction and low inertia.

Example of low friction low wear interface is hard race ceramic apex seals and rotor housing hard chrome surface while having low friction and low inertia.

However, another example of a high wear low friction interface is spring tempered steel and ceramic apex seals...

I dont know why they didnt just put a thin stamped steel "slipper" behind the ceramic apex seal instead of coating the tips of the springs.

------------
Stock Mazda steel apex seals are heat treated to about the hardness of the housing hard chrome on the wear surface and about the hardness of the spring steel on the back where the spring rides.
Unfortunately, despite their low friction they have high inertia. and material property change with heat. Both of which limit engine RPM.

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Old Mar 11, 2024 | 02:30 PM
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Originally Posted by BLUE TII
The 3mm NRS ceramic seals I purchased came with springs that appeared to have thick ceramet coating at the tips where they touch the ceramic apex seal.

As for friction and wear.

A low friction interface can be a high wear situation or a low wear situation dependent on the hardness of both materials.

Example of high wear low friction interface would be soft race sintered Carbon/Aluminum apex seals and rotor housing hard chrome surface. The Carbon/Aluminum mixture is soft and wears very quickly despite having low friction and low inertia.

Example of low friction low wear interface is hard race ceramic apex seals and rotor housing hard chrome surface while having low friction and low inertia.

However, another example of a high wear low friction interface is spring tempered steel and ceramic apex seals...

I dont know why they didnt just put a thin stamped steel "slipper" behind the ceramic apex seal instead of coating the tips of the springs.

------------
Stock Mazda steel apex seals are heat treated to about the hardness of the housing hard chrome on the wear surface and about the hardness of the spring steel on the back where the spring rides.
Unfortunately, despite their low friction they have high inertia. and material property change with heat. Both of which limit engine RPM.
how are you 3mm ceramics tracking a long
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Old Mar 12, 2024 | 01:31 PM
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I sold the 3mm ceramic seals before ever using them.

My idea was keep the same engine/turbo set-up and fix/refine it unill I felt it was reliable enough for 2 brand new rotor housings and the ceramic seals.

However, once I started using Mazda stock 3mm seals instead of aftermarket seals I never had apex seal issues. If the engine detonated hard it would break a front or rear plate at the upper dowel.
The factory 3mm seals were easy enough on the rotor housings and I was able to keep using the same set (not the rotor housings previously destroyed by aftermarket seals).
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Old Mar 12, 2024 | 02:50 PM
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Good lesson to learn. People are so afraid of OEM but they are significantly stronger than most aftermarket seals. Even in 2mm
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Old Mar 12, 2024 | 09:27 PM
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As has already been mentioned I find ceramics are really only useful for housing and apex seal wear preservation - essentially a 'buy once cry once' scenario. To rely on them to be any stronger than stock seals against a detonation event is folly.
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Old Mar 12, 2024 | 10:55 PM
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Originally Posted by dguy
As has already been mentioned I find ceramics are really only useful for housing and apex seal wear preservation - essentially a 'buy once cry once' scenario.
This is the main reason why I'm considering ceramics. It's been said that in a non-turbo they should last "forever."
I haven't seen anyone post their experience in that application or at least with a street car, probably because no one has been dumb enough to spend that kind of money for little power.
It didn't make sense when you could find used rotors or housings for $100, but those days are gone.
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Old Mar 12, 2024 | 11:40 PM
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From: sb
Originally Posted by j_tso
This is the main reason why I'm considering ceramics. It's been said that in a non-turbo they should last "forever."
I haven't seen anyone post their experience in that application or at least with a street car, probably because no one has been dumb enough to spend that kind of money for little power.
It didn't make sense when you could find used rotors or housings for $100, but those days are gone.

I'm running some single piece, single spring ceramics out of the Mazda LPG/Pump engines that had a pretty large production run in my TII swapped MGB and 2 piece Ianetti's in my FD. I haven't had to tear down the MGBs engine but I can say my FD still has perfect rotor housings after 20k. I've also put a few sets of ceramics in customer engines. Spending a few grand on seals that don't wear out housings in a well tuned system is definitely slept on.
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Old Mar 17, 2024 | 02:51 PM
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Originally Posted by dguy
I'm running some single piece, single spring ceramics out of the Mazda LPG/Pump engines that had a pretty large production run in my TII swapped MGB and 2 piece Ianetti's in my FD. I haven't had to tear down the MGBs engine but I can say my FD still has perfect rotor housings after 20k. I've also put a few sets of ceramics in customer engines. Spending a few grand on seals that don't wear out housings in a well tuned system is definitely slept on.
What sort of compression numbers do you see with them?
Have you done any 35+psi boost combinations with ceramics?
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Old Mar 17, 2024 | 05:14 PM
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Originally Posted by rx72c
What sort of compression numbers do you see with them?
Have you done any 35+psi boost combinations with ceramics?
The single piece, single spring units from Mazda's LPG engines do read lower in low speed tests, in the low/mid 90s, most of the two piece setups on top of new housings chill at 100-110 depending on what type of overlap on the porting. I shoot for ~21-23 psi on most of the race/track engines I build so as to last the 45ish minute sprints most of my clients do, throwing another atmosphere of boost certainly isn't going to change how they behave other than if you spit a seal prepare to hand over your wallet - which in reality would be the case if you did the same on an atmo setup.
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Old Mar 19, 2024 | 07:49 PM
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Originally Posted by j_tso
This is the main reason why I'm considering ceramics. It's been said that in a non-turbo they should last "forever."
I haven't seen anyone post their experience in that application or at least with a street car, probably because no one has been dumb enough to spend that kind of money for little power.
It didn't make sense when you could find used rotors or housings for $100, but those days are gone.
a few years ago, when i realized that the older parts were drying up, i came to the conclusion that they make sense (for me, at least). so i will be dumb ... enough. i just have a few other fish to fry first.
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Old Mar 19, 2024 | 11:55 PM
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Originally Posted by dguy
The single piece, single spring units from Mazda's LPG engines do read lower in low speed tests, in the low/mid 90s, most of the two piece setups on top of new housings chill at 100-110 depending on what type of overlap on the porting. I shoot for ~21-23 psi on most of the race/track engines I build so as to last the 45ish minute sprints most of my clients do, throwing another atmosphere of boost certainly isn't going to change how they behave other than if you spit a seal prepare to hand over your wallet - which in reality would be the case if you did the same on an atmo setup.
What fuel are you using at 21-23psi

100-110psi is good compression IMO for ceramic seals
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Old Mar 20, 2024 | 10:17 AM
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From: sb
Originally Posted by rx72c
What fuel are you using at 21-23psi

100-110psi is good compression IMO for ceramic seals
Anywhere from 91 with a somewhat heavily biased meth in a water/meth mix to our standard VP 101 at every track in the area. Nothing crazy, and E85 consumption is a bit much for the application.
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Old Mar 22, 2024 | 06:20 AM
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Originally Posted by dguy
Anywhere from 91 with a somewhat heavily biased meth in a water/meth mix to our standard VP 101 at every track in the area. Nothing crazy, and E85 consumption is a bit much for the application.
Very nice. Impressive work
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