Anyone Know how an RX-8 rotor compares to the one founds in a second gen. I know they are lighter and was thinking about building a new motor for my '88 with all original except the rotors...and possibly eccentric shaft But i cant find any info on such a project. Anyone tried this?

 

Do you realize what you're trying to do?

Do you think you are magically going to gain the same power as the RX-8 engine just by swapping rotors?

Do you know how different the RX-8 engine is using the side-port exhausts?

Do you know the RX-8 motor uses a 3-stage intake system?

Do you know the RX-8 motor redlines a lot higher than any of the FC stock 13B's?


-Ted

 

Racingbeat I believe tried the Rx-8 rotors. In their project car they found not appreciable difference in power between them and the s5 N/A rotors. just use the s5 rotors, they're gonna be waaaaaaay cheaper

 

i would like the idea of the rotor housings/ ports more, or maybe turbo rotors in an rx8 engine

 

I think someone on this board e-mail'd Dave Lemon of mazdatrix regarding this, but I think he popped his rx8's motor and tossed in some S5 NA rotors instead and he felt almost no difference between the two, anyone have that e-mail?

 

I would think the S5 rotors would not work correctly as they do not have the keystone type side seals used in the Renesis. These seals are there supposedly for sealing the combustion chamber better with the side exhaust ports. This same feature would also seem like it would make it more difficult to use the Renesis rotors in an earlier engine.

Vince

 

I ran into my old mechanic (he now works at a Mazda dealership) and I asked him if the Renesis swap had been done yet (RX8 to S4/S5). He did not know of anyone doing it, but when it comes to cars, anything is possible if you have the funding. But he did say that the rotors gained no real HP.

 

This is about as good as the rotary has no rev out and can go to the moon.

The FE rotors also are balanced based on oil volume dynamics and not static as the FC.

Henrick "sorry if I miss spell your name" swapped the FE rotors in his FC not the other way around. He claimed he saw no gains over this S5, S4 rotors in the S4 and S5 motors. You also have to use some S4, S5 rotor parts to keep from chewing the crap out of the internals.

And for the repeat the FE motor is getting its more drastic power from its dynamic staged intake and electronic TB and 6injectors for fuel atomization, in conjunction with its drastically retuned ignition with modern MAF/MAP style tuning.

 

I remember the thread in question an I believe Dave at Mazdatrix was using them in a race car of some sort. I believe there wasn't a noticeble difference between the S5 rotors. The Rx8 rotors are lighter I believe and have a higher compression ratio. I think the only advantage to using the Rx8 rotor is they are about $200.00 cheaper than series 5 rotors. One thing to note though is I think the Rx8 rotors use a 1.5mm apex seal so the rotors have to be machined to accept the 2mm seal of the 13b.You also have to use the 13b corner seals. May have to use the Rx8 front and rear counterweights. I'll see if I can find the thread in question.

 

Here is the threads in question:

https://www.rx7club.com/forum/showth...RX-8+rotors+FC

https://www.rx7club.com/forum/showth...RX-8+rotors+FC

 

Where did you hear this?

The FE uses 2mm apex seals and has an additional oil scraper or oil seal that is a widget. The rotors are .3 higher then S5 compression 10.0 compared to 9.7 and is .24lbs lighter then S5 rotors.

 

I thought I read it somewhere on here, but I think I was wrong. I posted that before I searched for the threads about it. Seems the machining is to make the apex seal groove deeper so they can accept the taller 13b seals. What about the counterweights? No one has mentioned them.Will the S5 ones work or am I correct about the Rx8 ones?

 

And are'nt the side seals in completely different spots than ALL the other rotors ever built?

 

The only difference between the RX-8 rotors and S5 rotors is the compression ratio. The RX-8 has 10:1 ratio as opposed to the S5 rotors being 9.7?:1 Not much of a difference at all, maybe a few hp. Go with the S5 rotors because they are less expensive and you can make up that small amount of hp somewhere else.

 

No, too much of a hassle, sides I figured people would just skip to the end to find the resolution. I did read the first 1.5 pages but got annoyed and just posted what I thought because it was all bullshit with no real answers, I just went back and read the .5 pages I skipped and congrats on your answer.

 

Not really...

The RX-8 rotors are "shaved" for later closing of the side ports.
The RX-8 rotors run thinner (top to bottom) apex seals due to the fact that there are no peripheral ports; these seals will most likely flex and bow-out with the earlier 13B engines peripheral exhaust port.
I think even the side seals are a different dimension.


-Ted

 

There is also mention in some of the earlier Mazda specs about an improved gear profile.

 

Found the thread and the e-mails from Dave Lemon at Mazdatrix. http://www.teamfc3s.org/forum/showth...ght=dave+lemon