2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

eccentric shaft????

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Old Jan 10, 2007 | 09:08 PM
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eccentric shaft????

how hard is it to swap out the rx-8 eccentric shaft to my 87 na??? is it just a bolt on or will i need to goof with it. and will it increase my redline?
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Old Jan 10, 2007 | 09:11 PM
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no it wont increase your redline. you dont need to swap your e-shaft... the n/a e-shaft can handle up to 500hp with out breaking. if you are wanting to up your redline you need to rebuild and cryotreat your engine and go with a standalone fuel managment system... and a port job to help out on power.

Last edited by rx7b13; Jan 10, 2007 at 09:18 PM.
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Old Jan 10, 2007 | 09:19 PM
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It should bolt right in. Its lighter, and while that won't improve power or raise redline, it does lower the inertia of the reciprocating assembly, allowing for faster acceleration.
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Old Jan 10, 2007 | 09:20 PM
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kinda like a lighter flywheel
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Old Jan 10, 2007 | 09:22 PM
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Originally Posted by rx7b13
no it wont increase your redline. you dont need to swap your e-shaft... the n/a e-shaft can handle up to 500hp with out breaking. if you are wanting to up your redline you need to rebuild and cryotreat your engine and go with a standalone fuel managment system... and a port job to help out on power.
Tell me... how does cryotreating internal components raise the redline?
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Old Jan 10, 2007 | 09:26 PM
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i didnt mean for the cryoteating to help raise the redline... its just something that would be good to do while the engine is apart and if you are gonna run higher revs then the cryotreating will help the engine from blowing and apex seal and a coolant seal
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Old Jan 10, 2007 | 09:37 PM
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Originally Posted by rx7b13
i didnt mean for the cryoteating to help raise the redline... its just something that would be good to do while the engine is apart and if you are gonna run higher revs then the cryotreating will help the engine from blowing and apex seal and a coolant seal
No it wouldn't.

Cryotreating improves resistance to wear, not brittleness.
It would have no effect on coolant seals. Cryotreating has no affect on silicone, viton or rubber.
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Old Jan 10, 2007 | 09:42 PM
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it increases the strength of the coolant channels... i know there is no way you can cryotreat silicone. MY APOLOGIES I DIDNT MEAN THE COOLANT SEAL I MEANT THE COOLANT CHANNEL
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Old Jan 10, 2007 | 09:52 PM
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The Cryo Treating Process:
How does the process work? The part or parts are placed into a processor and then slowly cooled to -317°F. It is held at that temperature for 20-60 hours depending on the part and material. It is then slowly raised to +375°F, then allowed to slowly cool to room temperature. Although not apparent to the naked eye, the changes to the part are significant. First, it creates a much denser molecular structure. The result is a larger contact surface area that decreases friction and wear. Second, it relieves internal stress, a result' from manufacturing, eliminating potential failure points in the part. And contrary to popular belief, this process actually decreases brittleness when done properly.
As stated from www.300below.com It decreases brittleness when done properly. You were correct in the fact that it decreases wear tho.

To get the redline you wish to find, you have to first lighten the complete rotating assembly. Rotors (Racing Beats http://www.racingbeat.com/FRmazda2.htm ) E-shaft counterweights and flywheel. Along with that, you would need the ability to cram the air necessary for the engine to breath properly. This would be some sort of crazy port job, custom intake and a turbo that can flow the required ammount of air within its efficiency range.Then you need the ability to expel said air after ignition. The rotors and counterweights alone are 2300 bucks from Racing Beat. You would be looking at roughly 10k into an engine properly built before stand alone.

Im sure there are other things that need done, but from what I have learned about the rotary and the countless performance piston engines I have built, that is what I know is the good start to what you want.
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Old Jan 10, 2007 | 10:19 PM
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Cryotreating does not affect yield strength, so it would have no affect on the cracking of water jackets.
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Old Jan 10, 2007 | 10:31 PM
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Originally Posted by turboefini88
The Cryo Treating Process:


As stated from www.300below.com It decreases brittleness when done properly. You were correct in the fact that it decreases wear tho.
I fail to fall into quick belief from a sales pitch with no empirical data. The theory of cryo treating is the change in temperature allows the conversion of retained austinite into martensite, and none of the data I've read on the subject shows that it would affect yield strength or brittleness.

Regardless, none of this has any affect on the fact that the seal grooves crack from overheating, and improving wear characteristics on such a part will not prevent this.
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Old Jan 11, 2007 | 08:12 AM
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I have my doubt about cryo treatment. Can somebody link me/refer me to an SAE (or some other technical publication) that actually has real data?
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Old Jan 11, 2007 | 09:26 AM
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www.sae.org They have a search engine onsite.
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Old Jan 11, 2007 | 11:54 AM
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Originally Posted by turboefini88
www.sae.org They have a search engine onsite.
So they do. It's not very helpful. Anybody know of a good technical source for this type of information? Something along the lines of material engineering(?).
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Old Jan 11, 2007 | 09:08 PM
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Honestly, there's not a heck of a lot on it. Everything I've read has been through private papers I got at school.
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Old Jan 11, 2007 | 09:16 PM
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waste of time and i doubt the OP realizes that the engine needs to be completely stripped apart to replace the e-shaft. it's not like a piston motor where you can drop it out the bottom of the motor. i came to this conclusion by the term "bolt in", well yes if you mean removing every bolt on the engine then yes i guess it could be considered a bolt in upgrade.
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