Tronics

I'm not sure if this is an issue in the RENSIS as it was in the 13b's. But the 13b's had to be re-built around every 60k-80k miles. Could their possibly be more potential for the RENESIS if it is rebuilt? Has mazda addressed this issue? I don't remember ever reading/hearing anything about this. Thanks in advanced.

RX8Lover

drew

I would say no, 13B's and rotary engines in general are actually very reliable, what causes them to fail in 3rd gen RX-7's (probably where you heard that) mostly is the fact that they are turbo'd and usually driven HARD, a major reason for failure is improper tuning for modifications.

There's no reason why a N/A rotory engine won't last ~200K miles if taken care of properly.

I have 101K on the original engine in my FD and it still runs close to perfect.

O.R.A.

Knock or overheating is the only thing that'll kill a Mazda rotary, as far as I know. Those things keep spinning forever with decent maintenance.

Heck, I know plenty of people starting out with 100,000 mile 12A's on their Spec RX-7 race cars and winning...

khoney

BS. 160K and still going strong (with synthetic, BTW). Bet you heard that from a pissed-on salesman :D

CERAMICSEAL

Unfortunately this is not entirely untrue,although the numbers are a bit skewed. After 1989 it is rare to see a rotary last much beyond 100k miles.I would say the average is between 70 to 120k miles. From time to time I see one that has exceeded maybe 160 or so( this is unusual). The culprit is the oil metering system adopted that year. Earlier models ( with mechanical oil metering) often met and surpassed these figures. The most modern system has a lot of changes incuding a pump by Mikkuni and dual nozzles directly at the housing.

SA22C

This instantly set off my BS meter, but I'm not as familiar with the FC3S as the SA22C/FB33, so I decided to do a little research. There is nothing that I've found that indicates that the electronic OMP is any better or worse than its mechanical counterpart. In the course of my research, I never found any contention that NA motors were any less durable in '90 than in earlier years.

So in short, I don't buy it. Durability was decreased by the addition of the twin turbo system for the 3rd generation, coupled with insufficient cooling. There is no reason to suspect that the Renesis will have the durability problems of the 13B-REW.

mikeb

I like you pic matt

CERAMICSEAL

Don't throw the bs meter on alert for me my friend. I have more experience with this stuff than you realise.
There's nothing wrong with either style of metering system apart from the fact that the electronic style eventually suffers stepper motor failure. That's not the problem. The electronic version is designed from the start to supply less than the previous one. This is in order to reduce hydrocarbon emissions. That unfortunately comes at the expense of some apex seal life. That's a fact. If I might speculate, it is my observation that those driven a little harder( more revs) last longer. The ECU/PCM uses MAP sensor, TPS and I believe tach to decide how much oil to provide.
I've seen automatic lady driven cars with 60k miles have engine failure. Broken apex seal/s.
You are correct in pointing out the reduction in life with addition of turbos(although I've even seem extreme cases with these, like 170k on an original motor of a customer of mine. This is very rare.)
The first time Mazda made a significant change to the metering system since 89 was 99 when the rotor housings changed to facilitate revised metering nozzles and the addition of a tiny o ring seal(smaller orifice in nozzle providing a more constant supply) These are the housings presently available in the US. N3Y1 replacing N3A1.
By the way if you observe some of my previous posts you may note that I'm a little bit more than a fan and I also own all generations so don't cast stones at me quite yet.

SA22C

I cast no aspersions on your character, I've just a) never heard of the later model NA cars having shorter engine lives than the older models and b) have found no evidence to support that claim. That being said, it would appear that you run a shop, and I don't, so you have the benefit of practical knowledge.

At any rate, neither www.nopistons.com nor www.rx7club.com has any mention of s5 engines being less durable, and there are some very knowledgeable guys on both boards.

8_wannabe

Unwarranted allegation. I read all (5) of his posts too. Besides taking a real good jab at Ike who was being a druid one day, gettingan8 has offered generally constructive comments. I agree he should offer a positive comment from time to time, but he is not just posting to be an @-hole; he is offering legitimate concerns.

CERAMICSEAL

I think you mean Tronics (who has 5 posts.) I also read his posts and he seems very neutral and intelligent. His attack of ikewrx (often considered a troll) may have been even a little overzealous.
He asks pertinent questions and he does actually own an 8.

CERAMICSEAL

Hey Ryan,are you suggesting that without being modded you won't break apex seals and that detonation is the only cause of the same?
And by the way I do generally agree with your assessments.The cooling systems are finicky and difficult to get the air out of.This becomes exaggerated by amateurs making mods.The same applies to engine management alterations without proper consideration for fuel supply, ignition timing, intake air temps, pre-existing gas leakage(combustion gases that is)etc.A lot of people who are tinkering don't understand any of these functions.

daedelgt

CERAMICSEAL, the fact is, that the FD runs a much greater amount of oil injection that is nescesary. If you look at the oil injection for the 8 and the FD, you will notice a large disparity between, what should otherwise be the same amount of oil injected. The reason, is that the 8 is able to much more precisely monitor the conditions of the combustion chamber, and can adjust as nescesary. I believe I can recall an SAE paper on the subject I read not too long ago. It was about race built Mazda motors vs the factory 13B-REW.

wakeech

and the fact that there aren't any more big holes in the perhiphery of the rotor housings.

FD's were unreliable because of the over engineering and price cutting of the 13B-REW. S5 motors aren't any less reliable than S4's, and actually improve on a number of little niggly problems that really stick out on motors that're +15 years old.

in short, all this talk about rotor motors NEEDING to be rebuilt every couple of years is baloney. don't put any stock in it.

SpacerX

Also addressing the other part of Tronics' question, I recommend you read through Canzoomer's posts HERE

Bottom line, as far as "potential" of the Renesis goes, evidence seems to suggest fuel and timing maps are all that's necessary to achieve significant gains in both power and economy.

daedelgt

My car will be 12 years old in about 6 months, and it has never had a rebuild. 55k miles on the odo and I'm still pulling 19in/Hg.