I like certainty. Newbie that I am here, I feel the need to defend almost every thread I start with "I searched already, but..." or "after googling this subject...."

Fair enough. It's fair that before I go spouting off on yet another matter that's been covered a zillion times I should have to provide some proof that I tried to independently find the answer on my own, to no avail.

This is yet another such occassion.

If you google the subject of the long term reliability of the Renesis motor, or search the matter here, you find opinions that run the range. The one thing you simply can't find, however, are hard, cold statistics.

Thee is much topical discussion about how the Renesis performed admirably during the 24 hours of Le Mans, winning the competition, and looking nearly brand new after doing so.

I like statistics. They provide me assurance. They eliminate emotion from the quest of trying to find basic answers to basic questions, and emotion can only greatly complicate such inquiries, without aiding the end goal.

So, after much ado (and blabber), I hereby ask, after diligently trying to find the answer independently:

Does anyone know how the now 2 year old Renesis motor is holding up from a mechanical reliability standpoint versus the last generation version found in the RX-7, or, for that matter, versus conventional piston based motors?

And is there an objective/comprehensive source that provides data regarding this matter?

I am really quite interested.

Thank in advance.

 

Wouldn't we all like to know that? IMO the only authoritative source for such an assessment on the Renesis engine would be Mazda and they ain't talkin'. Who else would have access to the comprehensive data needed to judge the reliability of the engine? A dealer here and there, an owner here and there with their individual data is only a small part of the picture. So, it is very unlikely you will ever get the authoritative assessment you are looking for. However, you could set up an intelligence collection operation to recruit an agent in Mazda...

 

How do you expect long-term data on a motor that is only two years old?

Since Mazda is the only source of ANY data, how can you require objectivity?

The best you can expect is hundreds of short term, parochial, biased, and un-bojective stories with varying levels of empirical data.

S

 

the 100,000th rx8 was produced around this time last year. let's say that 1000 engines have failed, i don't think its anywhere near that many, probably closer 200-300. But assuming 1000 failed engines, that's only a 1% failure rate...on a total production number that's a year old.

i didn't find any definative numbers on the number of piston engines that failed, but one site that sells remanufactured engines claims that the national average is 6% (sounds a bit high to me).

basically, like every negative thing in life, a very small, yet very vocal group make it seem like the problem is much worse than it is. not saying those that needed to have an engine replaced shouldn't talk about their experience, just that you always hear about those that are having a problem. no one is going to search out a car forum to post that they aren't having any problems and everything is working great.

 

the renesis was NOT run in LeMans.

glyphon is close to the correct numbers. but he's wrong about that "no one is going to " hell i searched and found this forum before the car was out to talk about how cool it was going to be

the real reliability numbers would be coming from the star mazda race series(ask member Lschiavo for one since he drove there-winningly- last) also the speed source racing folks, the formula women series in the uk and the new endurance series there. outside of those there is also the Astra Racing running a SC rx-8. plus there was some endurancerecords set a year or so ago. if you search Ikewrx's post you will probably find him argueing how meaningless the records were

 

So, let's start a "Poll" about this and tell everyone at RX8 club to vote?

Maybe, at least we could have an idea of how the engine might be holding up.

Something like:

No "major" engine problem
(which means NO engine failure, engine rebuild, engine taken apart for major repair)

Yes "major" engine failure
(broken engine or major component of the engine that broke, NOT accessories)

Let's also add the transmission into the "Poll" (split between auto and manual)

No "major" tranny failure
(etc, like above but tranny related)

Yes "major" tranny failure
(etc, like above but tranny related)

Also, we should add in there the clutch.

Everyone should list how many miles they have on their RX8 and IF it's modded. If the mod's are significant engine modifications (Turbo/SC) then those people are politely asked not to vote.

Furthermore, if the “poll” is setup to show who voted for what, you can track the person and car to put things together.

Sound good?

 

Sounds great.

These are the things I can't decipher from the somewhat ambiguous Consumers' Reports analysis/verdict of the RX-8 mechanical reliability.

 

most likely in a poll on a forum... the stats for major engine failure would be higher... as more people come on to post negative stuff than positive about their car...

 

^OK, now someone has to start it...I might be too lazy to do it myself. PM me if you need some help or idea's on how it should be listed.

 

It takes millions of miles of data in all sorts of conditions to determine reliability. Such tests are performed before production, but for real world figures, we will have to wait.

In the meantime, consider that long term reliability should be excellent. There are no heads to blow, valves to break, timing belts to snap.......

 

I could do it, but here's a better idea, IMO:

There are a lot of mechanical engineers on board here. Given that there would have to be many control questions in any survey, and technical refinement to the questions (to separate the minor from major problems), maybe someone with an engineering background would be in a better position to devise a much better survey than I could that would more accurately record relevant responses/data.

I am not adverse to doing the work; just not confident I could do the job as well as a gearhead.

 

Agreed...lol, me either...

 

mech eng. don't learn anything about giving surveys...

but to collect this data would be quite complicated...

usage habits.. redlining? freeway? local? avg mpg? best ? worst? mods? dyno? other factors? break downs? fixes? improper maintenance? crash? location? weather? oil used? coolant used? tranny oil used? for manual: typical launch rpm? slip clutch? tire inflation? mileage? short trip? long trip?... could go on and on and on....

the best thing is just to keep on the forum.. and see what other people are complaining about... so far seems good.... couple blown engines out in nevada and such.. but overall pretty good... if something were wrong we'd hear about it.....

so the best we can do... is find the worst the engine can perform on the forums...

basically a " my engine sucks more than yours" competition

heh

 

Just because people post about blown engines doesn't mean its a chronic, common problem. I would wager you could go to any board for a particular car and find issues that people have had. The new NC Miata's have had issues with their clutches going completely out. People started blowing F20C's at 60k. Evo's have their differentials explode.

There's alway a risk of problems when you buy a new model of car, but generally companies can't afford to have the risk of thousands of engines blowing up; Mazda already did that once with the FD. You can bet they tested the Renesis quite well, but there are always going to be a few cases.

No engineer can tell you what will happen inside an engine long-term with any certainty, unless its actually tested. You can be sure that Mazda has run the Renesis to 100k miles or so, and they have made their best interpetations of the data they can. But ultimately no one knows how the fleet will hold up over time. Most indications are that it will be just fine.

 

zoom, i think you are in a different category. you searched the forum out to talk about the car. i actually found this place and did research before i bought the car. i can't really fathom many people who aren't having any problems they need help with and want to discuss the car with other owners is going to come search the site out and start a thread just to say "i'm not having any problems what so ever". but who knows, maybe i'm wrong, but on the different car forums i've spent any amount of time on, i've yet to see that post

...and because i said that, one is surely being posted right now

also, any poll taken on this site (or any site like this) is not going to be a scientfic poll because just by the fact that we are here, we do not make up a truely random sample of rx-8 owners, at least not in a scientific sense. but, the poll, assuming enough people responded to it could show some general trends.

 

lmao.

 

quite a few people are right now thinking that is the understatement of the year
hahahhahahaha

 

Rotorocket just start phoning the various race sources i mentioned an ask how many hours the renesis is running betwen tear downs or seal failures.

hmm maybe ill do that for rxtuner.....

 

When people start getting 100-150K on the engines and start doing rebuilds, then we will be able to tell. Your not going to get much data without taking a bunch of engines apart and looking at them, imo. The engine is only a couple of years old. Try finding similar data for the LS1 or 4G63 or some other engine that's been around a while. It's not found easily either. Manufacturers are really the only corporate entity interested in such data, and just try getting something out of them...

 

I know your joshing me, but hypothetically speaking, wouldn't that only reveal something about racetrack circumstances, versus real world (or daily driver) circumstances, which could vary dramatically?

 

Another thing to consider is that even if we magically could get the "true" numbers, my guess is that they would bias high. The renesis needs that little bit of extra care that we informed readers of this site know all about, but I would expect there are lots of people out there who end up with engine problems simply because they just assumed they could treat the engine like any other engine they've had, didn't check the oil frequently and all, and boned the thing because of their own not-taking-care-of-it. I mean, even on this site, how many times have we seen the "Oh! I flooded my engine!" with the eventual admission "I moved it into the garage", even though everybody knows you're not supposed to do that.

 

no im serious. Racing is and always has been used by manufacturers for testing and developement. How the engine endures under race conditions is a very good indicator of normal on road durability. it wont tell you how it would fair being neglected or say driven at low rpms in extreme hot conditons over an extended period of time(vegas engines). but it will give you a good idea of reliability,

and calling them up is no big thing. at least a few of them I know are happy about sharign info liek that and Luis schiavo is a member here and could tell you about his engine's durability first hand.

 

Given Mazda's last financial experience with the FD's, I guaran-damn-tee you that Ford made them test the SH*T out of the engine to make sure it would be able to live to at least 120K without major issues if maintained.

This is also why Mazda may be so gunshy on the factory FI. Mazda really just needs to offer the car, and then an offroad no warranty kit FI system to shut everyone up. Mazda even said it themselves that the aftermarket would provide all the FI options you'd need.

The reliability of the stock engine in NA form is on the bottom of my list of things keeping me up at night.

I saw Bern's SA with 210,000 original miles on the car and tranny do a whopping 52WHP on a dyno (his aux ports were not working), seeing as the car only did about 100BHP stock, and the ports were stuck, thats not a bad result.

 

I do have to mention the history of the rotary up to the Renesis because that is relevant information. In 10 years come back for relevant information on the long term durability of the Renesis. Hopefully the 12A/13B history will shed some light on what you'll probably see though.

I'm actually going to go backwards in time starting with the most recent. The 3rd generation RX-7. Good luck finding one of those engines that makes it to 100,000 miles. If you hit about 50,000 you were getting near the end. I have seen 1 make it to 100K though. This must mean the engine sucks or was the problem elsewhere and not with the engine? The cooling system was the worst of all the RX-7's, the engine made the most heat in the engine bay as it had the worst ventilation and airflow of the RX-7's, the engine made the most power of all the RX-7's. What seems to be the culprit here? Heat. The excess heat due to inadequate cooling caused the housings to warp at some point and for coolant to leak into the combustion chamber. This warrants a rebuild. Add to this the complicated twin turbo system that was terribly unreliable in itself and it appears that the engine is terrible for longevity. It isn't in the right conditions as with any engine. That car masked the real cause of engine issues and made people think the rotary sucked. Not true. When you see people talk aobut the RX-7 engines as being unreliable, they don't really know what they are talking about. If I pulled away most of the cooling ability from your piston engine and ran it too hot all the time, it wouldn't last long either. Also remember that many people tried to improve the performance in the wrong ways and blew their engines up themselves from detonation. That's also not the engine's fault.

The 2nd generation RX-7. 2 versions, a 6 port nonturbo and a 4 port turbo. These cars are much more likely to be found with higher mileage. Many turbo models have blown up but when you see the average upgrade path of the kids that usually own these, it's similar to the 3rd gens. These RX-7's strangely enough are the ones that you see abused more than any other generation. Anyone who went to Sevenstock can tell you there were more bad looking 2nd gens there than any other generation. It's not uncommon at all to see a 2nd gen go over 150K miles on the original engine. When I first got my first 2nd gen I too modified it in very bad ways. I even had the ceramic from 2 separate spark plugs fall through the engine! They made a mess and the eing kept running. I pulled the engine out at 136,000 miles and it would still pass emissions. I had another engine that I had built that was ported that I swapped so I didn't pull the engine because it was dead. It had been severely overheated a few times as well too. I've seen T-II's go over 170K on the original engine. You can find alot of these cars will die but their engine's won't. They'll get wrecked or have some other issue but the engines in the junkyards will usually still run. It doesn't mean they shouldn't be rebuilt though. The nonturbos have the ability to go over 200K miles. The key is in taking care of the engine with oil changes and not doing stupid things like I did. Alot of people don't take care of their engines. How is that an engine reliability issue?

The 1st gen RX-7's had some nearly indestructible engines. These things just seem to go and go. The 1st gen had the best cooling and had the best ventilation under the hood. They also made the least power of the RX-7's. See why they last so long? My friend Dave has personally had 2 1st gens that had eclipsed 250,000 miles and still ran. Mine is just getting broken in at 106,000 miles. Bernie at Sevenstock dyno'd his 12A that had 220,000 miles. It only did 53 rwhp but the carb secondaries weren't opening and the engine only puts out 110 fwhp anyways. If his carb worked properly he'd probably still have dyno'd right around where it should have. Not too bad for an old car with a questionable history.

You're probably noticing that if relibility kept getting lower as each successive RX-7 generation came out, how poor is it now? You have to remember that you don't have turbos heating up the engine bay. You don't have turbos heating up and putting more stress on the oil and the coolant. You aren't pressurizing the engine. You have alot of things going for you that the 3rd gen RX-7 doesn't when it comes to reliabilty. You have better cooling that the 3rd gen did. That alone is the biggest part. These traits alone should take it back to the realm of the 1st and 2nd gen RX-7 nonturbos assuming people take good care of them. That would suggest that the engine is more than capable of hitting 200K miles easily as long as you take care of it. That's the biggest issue affecting reliability. The more you modify an engine and increase it's power output per it's size, the lower the long term reliability will be. How long will a Renesis last, take care of one with regular maintanence and let us know. There have been rotaries that just plain wore out somewhere after 350,000 miles. Let's see how close the Renesis can come.

You want empirical evidence, come back in 10 years when the miles have been racked up.

 

In the thread:
https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/renesis-side-seal-discussion-38411/

David Haskell said the following:

"I have built 18 of these motors for racing in Grand-Am Cup. I have not seen any issues with the side or corner seals. We have run motors for 50+ hours in racing conditions with an average of 4% loss of power. This is about the same as a raced piston motor. I don't really have any mechanical issues with the motors, and we run them in 3 hour races with an average rpm of around 7400."

I think this is pretty convincing evidence along with the other racing series mentioned in this thread that there are no major reliability problems with this engine.
--R