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Mill RX8 rotors for 3MM RX7 apex seals?

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Old 01-18-08, 12:13 PM
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Originally Posted by crispeed
How do you get better compression with the oil scraper?
i never said it made sense to me. i just said i read it somewhere, and now i guess it wasn't you that said it. i have NOT had the chance to work with Renesis parts yet, so i'm relying solely on what info i can get from others until i can do my own stuff. all i can say is whomever it was that said it, was someone that i felt to be credible or else it would have just washed in one ear and out the other.
Old 01-18-08, 12:16 PM
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Originally Posted by 680RWHP12A
you could also flip the rotors on a s.p or b.p application
Hey!
This thread is about milling for 3mm!!!!
Old 01-18-08, 12:31 PM
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Originally Posted by diabolical1
i never said it made sense to me. i just said i read it somewhere, and now i guess it wasn't you that said it. i have NOT had the chance to work with Renesis parts yet, so i'm relying solely on what info i can get from others until i can do my own stuff. all i can say is whomever it was that said it, was someone that i felt to be credible or else it would have just washed in one ear and out the other.

The oil scraper does not stop compression leakage from one chamber/side/face etc. to the other. Also most have found this oil scraper to produce extra abnormal housing ware in a very short time when applied to the pre-renesis housings. I have not personaly tested that claim.
Mazda states it's there to reduce blowby from the exhaust to the intake port. I believe it's there to protect the second oil seal/o-ring from the exhaust heat due to the position of the exhaust port and also from combustion temperature/heat due to excessive leakage from the new side seal design.
Old 01-18-08, 12:33 PM
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okay, i just spent a few minutes searching and came up with bupkiss. i spazz out from time to time, and misinterpret new information at times, but i can't shake the memory of seeing it somewhere. however, i'll chalk it up to my own psychosis and drop it as misinformation and a mistake on my part. it's already taken up way too much time in this thread. as i said, it didn't make sense, but whatever. i did find that you were the one that mentioned the thing about the excess housing wear though, so my memory 50% good. maybe too much rum?
This Thread

EDIT: yeah you were responding while i was writing this.
Old 01-18-08, 12:34 PM
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Originally Posted by crispeed
Hey!
This thread is about milling for 3mm!!!!
oops, sorry mr. top secret guy
Old 01-18-08, 12:36 PM
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Originally Posted by diabolical1
, so my memory 50% good. maybe too much rum?
Nah!!
It's not the rum. They say memory has something to do with age.
Old 01-18-08, 12:39 PM
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Originally Posted by 680RWHP12A
oops, sorry mr. top secret guy
'Top Secret' is a shop from Japan.
Have no clue why you thought I had any relationship with that shop.

The casting on the renesis rotor is so thin I wonder if it's any stronger than the previous S5/6 rotors? I really don't believe those rotors were meant for anything with the word horsepower in the same sentence.
Only time will tell.
Old 01-18-08, 12:54 PM
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Originally Posted by crispeed
How do you get better compression with the oil scraper?
Ask Rick Engman. He's the one who figured it out.
Old 01-18-08, 12:58 PM
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Originally Posted by crispeed


The casting on the renesis rotor is so thin I wonder if it's any stronger than the previous S5/6 rotors? I really don't believe those rotors were meant for anything with the word horsepower in the same sentence.
Only time will tell.

your right again!
ive seen alot of renesis rotor failures due to the thin casting cracking, leading to bearing failure.. (there is a really thin spot next to the bearing that prone to cracking)
this i why i would NEVER use these rotors in a boosted application where there is alot more load on the rotors..
Old 01-18-08, 01:45 PM
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Originally Posted by rotarygod
Ask Rick Engman. He's the one who figured it out.
Yeh you will get better conmpression one way but not the important way!!

When I see a renesis rotor make more power than a 9.7 rotor then I wil beleive it. Gauge compression is not improtant to me. That does not make power.
I know what's the difference between long vs short side seals and using the oil scraper vs not power wise of which it still is not higher that the non renesis rotor.

Last edited by crispeed; 01-18-08 at 01:56 PM.
Old 01-18-08, 01:47 PM
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Originally Posted by 680RWHP12A
your right again!
ive seen alot of renesis rotor failures due to the thin casting cracking, leading to bearing failure.. (there is a really thin spot next to the bearing that prone to cracking)
this i why i would NEVER use these rotors in a boosted application where there is alot more load on the rotors..
You have to remember to some 300 to 350 flywheel horsepower is a lot. and I'm talking about NA power too!
Old 01-18-08, 06:51 PM
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Originally Posted by 680RWHP12A
ive seen alot of renesis rotor failures due to the thin casting cracking, leading to bearing failure.. (there is a really thin spot next to the bearing that prone to cracking) this i why i would NEVER use these rotors in a boosted application where there is alot more load on the rotors..
Thanks, that was a good reply.

I think the savings is at least $300/pair. I'd have to check mazdacomp again. So it would be more expesnive to mill but the 3mm would be harder to break.

Compression is lower at idle but with 3mm but not relavent under load. With this being the case it won't balace out the higher compression RX8 rotors as I thought.
Old 01-18-08, 08:51 PM
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Here's an idea, buy some used 9.0 rotors, and if the seal grooves are at all out have them machined for 3mm seals.

a real good set of 9.0 rotors can always be had for like 200 dollars if you look around.


Originally Posted by GoRacer
Thanks, that was a good reply.

I think the savings is at least $300/pair. I'd have to check mazdacomp again. So it would be more expesnive to mill but the 3mm would be harder to break.

Compression is lower at idle but with 3mm but not relavent under load. With this being the case it won't balace out the higher compression RX8 rotors as I thought.
Old 01-18-08, 09:06 PM
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+1.




Originally Posted by slo
Here's an idea, buy some used 9.0 rotors, and if the seal grooves are at all out have them machined for 3mm seals.

a real good set of 9.0 rotors can always be had for like 200 dollars if you look around.
Old 01-18-08, 09:31 PM
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Attached Thumbnails Mill RX8 rotors for 3MM RX7 apex seals?-motivator1775137.jpg  

Last edited by Torque South; 01-18-08 at 09:38 PM.
Old 01-19-08, 10:17 AM
  #41  
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Originally Posted by rotarygod
Ask Rick Engman. He's the one who figured it out.
ahhhh ... redemption. perhaps it was one of your posts somewhere (here or over at rx8club), but i knew i read it somewhere. i really started to get worried about my memory there for a second. that kind of thing would bother me - although i'm trying to allow myself to let things like that go.
Old 01-19-08, 10:21 AM
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Originally Posted by crispeed
Nah!!
It's not the rum. They say memory has something to do with age.
boooo! way to go reminding me of how freakin' old i am ...

just joshin'. as i said, i never figured it. i guess i still can't ... and the only Renesis i have right now is sitting in my Rx-8 and (knock on wood) i have intentions of pulling that apart any time in the near future, so i'll have to wait for my hands-on experiences a little while longer. until then, you guys have to keep me honest.
Old 01-19-08, 12:34 PM
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Originally Posted by 680RWHP12A
there is not enough meat on the rx8 rotors to mill to 3mm, and sometimes not enough even for standard 2mm,

We've had great success cutting 3mm grooves on Rx8 Rotos for PP. N/A race engines.

Back when the Rx8 Rotors first became available, we sacrificed a new Rotor, dissected it and took carefull mesurements of critical areas were modifications would normally be made.
We've since have built many race engines using Rx8 components.

One example of late:

Name:  SNV30398.jpg
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Look at thread : https://www.rx7club.com/race-car-tech-103/94-rx-7-track-car-project-begins-506890/ pages 5 & 6. for more info.


Originally Posted by 680RWHP12A

the casting is real thin, ive seen too many new rotors go into the trash can for this reason...
This is true, just have to be carefull, and know what your doing.

Originally Posted by 680RWHP12A


also there are some mods you have to do to the side seals to get good power using rx8 rotors, not to mention throwing away the 3rd oil scraper ring...


Correct.
Obtaining good power from these rotors is not as easily done as w/ previous ones, but they will yield great power once the combination is found.
As w/ all progressions into newer technologies, it requires time, testing, and new ideas in mapping to find the tune that inevitably unleashes the extra power.

Close inspection of these Rotors has shown the Parabolic Arc of the flanks to be different in both shape and volume as compared to all previous series of Rotors.
Having found that, it becomes obvious the Thermodynamic characteristics are now different reflecting the changes in chamber geometry.
Tuning, in the traditional sense must therefore be adjusted if optimum performance is to be obtained.



Originally Posted by 680RWHP12A
for your application stick to the fd rotors if you want good results without a headache


Correct again !
If you are talking "TURBO" application, Rx8 Rotors are not even a consideration.
But on N/A engines, they do have their merits. ...... If tuned appropriately.
Old 01-19-08, 12:51 PM
  #44  
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^ thank you, good info for the N/A crowd. I will stick with the turbo rotors.
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