RX-8 40th Anniversary

I'm hoping that's the name of the RX7's engine, but I've started to dive down into the FD's engine and more than will likely compare it to the RX8's engine.
I've noticed that the exhaust port on the RX8 is rather, limited, to help with emissions, right? The RX7's exhaust port is much bigger and, on the housing?
Whereas with the RX8 is just an itty bitty port. The RX8 has higher compression rotors and the RX7 has lower compression rotors due to FI, and the RX8 is
N/A, So far I believe I am correct, but anything that I say if it seems off just correct me. I also watch Rob Dahm and I remember hearing something about the
Exhaust port on the RX8 is what really kills it. If we were to take out the turbos on the RX7's engine and compare it N/A, would the RX7 engine be considered
more reliable? Or is there something unique about the RX8's engine that makes it last a very long time? Of course with all engines, reliability lies with proper maintenance.
But if we do take the turbos out from the RX7, Would it lose a ton of power? I believe the RX8 is the N/A Rotary king, because the RX8 makes about 238-245 HP? And the
RX7 makes about 255-260HP?

I guess for the very big simple question, If the REW was N/A Would it be more reliable then the Rensis engine?

ciprianrx8

Emissions killed the rx8. Delete the cat, give it the oil and lower operating temperatures it needs, and you get a rotary equally reliable as those before it.
The infamous "unreliable" tag came along from retarded owners who didn't know enough to even check the oil level, let alone diagnostic shitty design on mazda's part and improve upon it, albeit at significant cost.

RX-8 40th Anniversary

Yeah, Thats what I figured with the RX8, Mine is gutted and stays cool even at 9k RPM after some slight adjustments...
I heard about the owners and its unfortunate they made the RX8 cheaper.
My plan is when the engine dies out, have it redone with a Bridgeport and exhaust port modified and get at least 200WHP. I plan on keeping mine too.

Loki

iTrader: (1)

You're not far off. I wouldn't port it, to be honest, there's no win in that. You can open the intake all you want, but it won't matter if the exhaust is constricted, which is the limiting factor for power on the Renesis. And there's nothing you can do about it beyond very light cleaning of the exhaust port.

Limiting factors on reliability are many, it's hard to compare REWs and Renesi. I don't have stats handy, but REWs wear out just like Renesis. Apex seal design was changed, oil injection management, compression ratios, etc. The exhaust port isn't the only change they made. I don't think it's fair to blame owners for all the problems, the root cause of death for a large portion of dead renesi has nothing to do with the engine core and everything to do with poor coils > clogged cats > dead engines. Secondarily, housing and side seal wear. Apex seal wear isn't really the main problem any more, but it was in the REW days.

UnknownJinX

Yes, the potato coils on the early RX-8s didn't help the matters one bit.

Also, NA FC made about 155 BHP stock while the RX-8 made about 230 BHP(6-port). Even the 4-port made 190 BHP, so there is also that factor.

It really just comes down to the fact that rotaries unfortunately don't have the economy of scales of some other performance engines, so the R&D budget was pretty tight. Given Mazda, if they had more money, they could potentially have figured something out about the emissions without sacrificing reliability.

Shower thought: you can almost see shadows of Renesis in the Voodoo engine: high-revving, low volume(only used in Shelby GT350), hand assembled, sounds great on paper, and not exactly reliable. Just not a particularly good combo for any manufacturer, it seems.

Shaozhou Zhang

First of all you don't Bridgeport a Renesis, search for it, TeamRX8 makes a good point.
Largely personal Idea, no data support:
Personal thoughts, there's a thread by 9krpmrx8 called "New renesis failing theory", a racer named Eric Myer chimed in discussed how side seals on a racing engine is very prone to faliure (especially without OMP), much more than Apex Seal. The consistent high EGT will cause the seal and seal sping to deteriorate, people who ran this engine hard regularly tend to have this problem, therefore I don't believe that "A redline a day thing", but many do.
The whole ignition+cat thing Loki mentioned is also a big killer.
5W20, nothing is wrong if you are running at 70 ℃ of oil temperature, but not 110℃.
Oil injection rate too low, far too low, I am currently going through 1L of JASO FC rated oil every 700-800 km.
S1 Oil pressure too low. FC3S, NA, 155BHP, 70psi? ,you can get over it. SE3P, 238 BHP, 9000 fuel cut off, 70psi? , ???????????????????????????
As for RX7, it does not have the highly engineered intake manifold like we do.

Read more: https://www.rx8club.com/series-i-tec...-210194/page6/

RX-8 40th Anniversary

hmm.. I checked out that thread and it's pretty interesting. But I haven't even thought of the FC's engine, those things seem way easier to work on too since it is an older car, but that's just me.
and I happened to use the same premix! I do have the LS coils though.

Loki, What part of the design with the REW that made the seals wear out? Was it just not enough oil?