Originally Posted by ultimatejay

And that's all that matters to me and all the other racers out there. If you want fuel economy, go buy a Honda.

Originally Posted by t-von

. The fact is the older side port pp exhaust 13b's will never equal the Renesis in terms of power AND emissions. There's no comparison. However, the total power advantage will always go to the older 13b's.

Originally Posted by t-von

???? Uhh no one said anything about fuel economy. To each his own!

Originally Posted by diabolical1

why do i get the feeling this is going in a direction of an argument? anyway, i'll try to clarify what i was saying before, and whether i succeed or fail, i'll hope to leave my side of the argument here.


when i quoted Rotarygod earlier, i was merely taking what he wrote (as it was written) and emphasizing it because i see (and hear) so many people attributing the power difference between the last production older 13B and the current MSP to the higher compression rotors, if not wholly, then mostly. i simply disagree with that and that's why i highighted it. when i responded to your question to him, i was just trying to point out that comparing the stock Renesis to older bridges and peripherals is pointless because you're using a different context. what's the use of saying older race ported engines make more power than Renesis engines that go through what i'd oversimplify as calling a "retune" (to go from 230-ish to 280). as far as i'm aware there's no change in the engine itself to facilitate this. the older race engines having more power is the result any logical mind would expect. if comparisons must be made, why not leave the comparison limited to an older 6-port with similar porting?

i realize racing is quite important to you, but for the majority of Rx-8 owners, and the handful of people that put Renesis engines in older Mazda, how many of them have racing in the forefront of their minds and would furthermore be willing to daily drive an obnoxious car? that's all i'm trying to point out. using a 6-port block (or even a turbo block with 9.7s) if you were to reach 280 (on stock or streetports) you'd have something prohibitively expensive, no emissions, and just bloody LOUD! Logan (GtoRx7) eclipsed 230 (wheels) on an RE block, if my math is right, that's on par with high 200s at the flywheel. so it is possible. however, how many Logans do we have out there?


280, pathetic? would you call an older streetported engine making 280 pathetic? again, keep the porting similar and then make the comparison. look, i'm not misguided enough to feel the need to compare the old to new. i have both. i enjoy both. i see each for what it is and that's where i leave it. however, your comparison is decidedly lopsided and with all due respect, to me, invalid. sorry.



first of all, you are absolutely right, you're comparing two different eras of rotary engines, and that's kind of why i see it as being pointless. i am not so out of touch that i don't realize there are many factors at work to make the Renesis do what it does. it's not just the zero overlap/side port exhaust or intake setup or electronics, or porting, it's the combination of everything. i realize that, and if it sounded like i was simply saying it was zero overlap or whatever, then i guess that's on me. maybe i should have taken the time clarify better.

for racing applications i am well aware that the older engines have an edge. they have decades of development and on-track experience, plus they can now benefit by modern electronics to shine even brighter. whether Mazda chooses to address the Renesis' shortcomings through time, we all have yet to see.

i don't know if i'm any clearer than i was before, but essentially i'm leaving the all-out, no-holds-barred stuff aside (i.e. radical porting) when i say the uses the side-port exhaust (and what it brings with it) to make more power than a comparable older 13B. surely, you can see that the sideport exhaust is the fundamental difference between the two, so electronics, rotors, intake, ignition, and the like would naturally get second billing even though they contribute to the overall package.

Originally Posted by Rxmfn7

With my N/A 20B setup, I am using Rx-8 rotors. Id love to have the time/money to get it all running and tuned, get a baseline number, pull the engine and rebuild with 9.7:1 13b rotors, and re-test again under the same circumstances. This is about the only way you will ever be able to see a direct comparison of what effect just the rotors themselves have. Unfortunately, I (nor most people) dont have the funds or time to do just a back to back comparison. And, without that, comparing 2 different peoples engines with different variables is pointless, apples or oranges no matter how similar they may be.
One of my favorite quotes from people sigs is rotarygods:
"If you aren't testing, you are guessing."
Unfortunately sometimes this isn't feasible, so you have to make a decision (guess) based on what you "think". I "think" rx-8 rotors will be a good choice for me.