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Renisis rotors

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Old 09-10-04, 10:04 AM
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Renisis rotors

any methods to drop the compression on them
Old 09-10-04, 04:48 PM
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Why bother when you have the 8.5 c:r and 9:0 c:r rotors?
Old 09-10-04, 05:09 PM
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because its a lighter rotor
Old 09-11-04, 08:46 AM
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I believe there isn't much left to machine on a RENESIS rotor. It is true you can retrofit one into older 13B's, but I think there is a side seal issue.
Old 09-11-04, 08:55 AM
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Originally Posted by badfish229
I believe there isn't much left to machine on a RENESIS rotor. It is true you can retrofit one into older 13B's, but I think there is a side seal issue.
yeaa, right now they are still loosing power with the renisis rotors.....I'll find the link
Old 09-11-04, 08:58 AM
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http://www.racingrotary.com/rx8rotors.htm

mazdatrix info, I trust mazdatrix
Old 09-11-04, 10:29 AM
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what year 13b has the lightest rotors and wats the compression on them?
Old 09-11-04, 11:50 AM
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Originally Posted by Aesop Rock
yeaa, right now they are still loosing power with the renisis rotors.....I'll find the link
You didn’t read the bottom update.

Update August 2 2004 -

I have an "update" since that original response ----- We took the "RX8 Rotor" engine apart (having MASSIVELY over-revved it when the trans broke in practice -- probably hit 14-15k at least, AND did it 3 times. Broke a few tension bolts, cracked gears, spun a bearing, etc.but still ran the whole Thunderhill Double National weekend!!). We ran it on the Dyno (dyno had been up-graded to full computerized) before taking it apart (did not know how much damage had been done). Rebuilt it, AND changed the porting some, AND used 89-91 rotors, ---- AND got about the "same" low power !!! REALLY puts a question mark back on/about the RX8 rotors. So --- WE still have not seen any MORE power from them, but WE are seeing (WITH the porting we had been using) "about" the same power ?????? Obviously, more testing needs to be done. Dave Lemon ---
Old 09-11-04, 11:51 AM
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Originally Posted by Aesop Rock
http://www.racingrotary.com/rx8rotors.htm

mazdatrix info, I trust mazdatrix
have an "update" since that original response ----- We took the "RX8 Rotor" engine apart (having MASSIVELY over-revved it when the trans broke in practice -- probably hit 14-15k at least, AND did it 3 times. Broke a few tension bolts, cracked gears, spun a bearing, etc.but still ran the whole Thunderhill Double National weekend!!). We ran it on the Dyno (dyno had been up-graded to full computerized) before taking it apart (did not know how much damage had been done). Rebuilt it, AND changed the porting some, AND used 89-91 rotors, ---- AND got about the "same" low power !!! REALLY puts a question mark back on/about the RX8 rotors. So --- WE still have not seen any MORE power from them, but WE are seeing (WITH the porting we had been using) "about" the same power ?????? Obviously, more testing needs to be done. Dave Lemon ---

Hmmm....

Different porting and "about the same HP", doesn't make any sense to me, maybe they were somewaht vague on the explanaiton.
Old 09-11-04, 01:28 PM
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basically its still shady....and not really worth it
Old 09-11-04, 01:58 PM
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very strange
Old 09-11-04, 08:30 PM
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interesting.....
Old 09-11-04, 11:51 PM
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Has anyone approached mazda about supplying over-length side seals?
Old 09-12-04, 04:00 AM
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And about the weight of the rotors, rx8 rotors are still heavier than race lightend S5 rotors.
Old 09-12-04, 09:44 AM
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I asked about using longer side seals to a member of the RX-8 Forum. Here's what he had to say:

Originally Posted by MarkJ
Renesis rotors do not have significant enough material in the recess to
drop cr enough for major boost. Longer side seals are intended to eliminate the
excessive clearance found in Renesis rotors so they can be used in engines with peripheral exhaust ports.

The side seal clearance on the RX8 looks to have been done by Mazda on purpose.
As the rotor crosses the exhaust port the exhaust gas would be trapped between the
outer oil control ring and the side seal corner seal area. In the old days practically zero
side seal to corner seal clearance was the hot set up. When Mazda adopted the side exhaust they had to prevent this blowby. Mazda had added a third oil ring to prevent the
gases from getting into the crankcase, and shortened the side seal to purge this gas.
But this is why you hear complaints of oil in the intake and hard starting/flooding problems.
It's strange how there is increased clearance for the side seals. This can quickly turn into a problem when porting the motor.
Old 09-14-04, 05:07 PM
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I have used RX-8 rotors for a PP N/A engine. It made 284 hp@8600 rpm compared to a similar 9:0 cr PP engine i built last year (it made 276 hp@8200) The real gain as i see it is in the midrange where the "RX-8 engine" picked up 10-15 hp. The hp on these engines is flywheel hp and the "RX-8" engine has since dyno'd in June been to a reputable rolling road where it made 303 hp converted to flywheel hp. All i can say is that RX-8 rotors works great for PP engines and the car an RX-7-83 rally car won it's first victory on a 1km long hill climb event 1.5s quicker than second car which was a Mitsubishi EVO 6 turbo rally car! On third place, 3 seconds behind the RX-7
was a N/A Escort with a 2.3l Pinto engine. I said go rotary!
Old 09-14-04, 07:24 PM
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I'm waiting on a certain supplier for reply if or not the RX-8 side selas can be dupplicated. Should have a reply in a week or so.
Old 09-14-04, 07:28 PM
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Originally Posted by Lasse wankel
9:0 cr PP engine i built last year (it made 276 hp@8200)
I hope that's an error! You meant 9.7:1 compression right?
Old 09-15-04, 01:23 AM
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No i really did use 9:0 cr rotors becausse cuctomer didn't have the money for new 9.7 cr rotors. How much increase in hp do you think is available with new side seals? Hopefully this winter i can build a 10:0 cr dragracr PP engine with big inlet holes, that should be intersting hp wise!
Old 09-17-04, 08:45 PM
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Originally Posted by Lasse wankel
No i really did use 9:0 cr rotors becausse cuctomer didn't have the money for new 9.7 cr rotors. How much increase in hp do you think is available with new side seals? Hopefully this winter i can build a 10:0 cr dragracr PP engine with big inlet holes, that should be intersting hp wise!
That would explain the power increase you experienced.
As for power increase with the new side seals there should be some significant difference. Even with the longest side seals available from Mazda presently for the rx-8 the clearance is way beyond the maximum amount normaly used on regular motors to operate efficently.
Old 09-20-04, 12:23 AM
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I hope very much that longer side seals can be available in the near future! Today i have the fortune to build another 13B PP rallycross engine for a customer in Sweden. Goal is to achieve at least 290 hp with a torque of 190 ft/lb at flywheel. I shall use a new Gene Berg carb but don't exactly know what size i shall go for? 52-56 mm i think should be good for hpand torque. I have seen vacuum drops for about 0.2 bar at 9000 rpm with aWeber 51 IDA. Any inputs carb gurus?
Old 09-23-04, 06:54 PM
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was at atkins the other day, a guy came in asking questions about the rx8... wanted to know how much lighter the rotors were... on a scale, the rx8 rotor atkins has weighs the exact same as a 3rd gen rotor...
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