boowana

Here's what I got, not from my normal sources, but a very reliable source indeed.
The RENESIS Engine was run under laod for the equivalent of 25 consecutive INDY 500 Races at...are you ready?... 17,000RPM. WOW!
The same engine was then installed into an employees car in Japan (obviously not an RX-8) and driven in all kinds of conditions including stop * go, city and highway for an additioanl 100,000 miles.
NOT A SINGLE FAILURE!:D :p :D :p :D :p

For those of us who might be harboring lingering doubts about the reliability of rotary engines..................

FORGEDDABOUTIT!!!!!!!!

zoom44

thats great boowana. now have you seen this

wakeech

gerblush dishln gasuh?? teskfun kalik xervib...

words cannot describe.

long live the rotary.

Quick_lude

Cool.. first mod: Remove rev limiter. :D

wakeech

wait a sec, that's at totally stock spec?? not at all different from what we're gettin' from the factory in the front of the 8??
if it's a bit different, whatever... if it's exaclty the same, holy @349*$ @#$*U, this'd be nearly the best engine of all time...

ZoomZoom

I will pray to god every night that this is true.

ZoomZoom

Bowana... what are you hearing about NAV and sunroof be offered?

roachman

Zoom44 are you suggesting that this is what every owner gets??

Boomana, very very cool engine. Have you heard about Nav??

zoom44

according to that webpage mazda is giving those to people in japan who preorder. and boo how long did it take to drive the second car to 100,000. japn is a small country and it seems to me it would take longer than the engine has been around. that is really amzing stats though. 17,000 rpm!!

Hercules

*drool*

rpm_pwr

This sounds too far-fetched for my liking. Firstly, how do you rack up 100,000,miles (about 160,000kms) in Japan of all places, in such a short amount of time?

Secondly 17,000rpm sounds WAY too high to me. It sounds like one of those 'friend-of-a-friend' stories. Let's see:

max RPM b4 e-shaft flex causes rotor drag on housings:
<'02 13b = 8500rpm
all out factory race 13b with modified centre housings = 12,000

Now you're saying that a stock RENESIS can hold 17,000rpm UNDER LOAD? No way. God I wish it were true though

-pete

rpm

That’s great news to hear about the reliability of the engine but the major problem with Mazda is not the engine. It's their service department that needs a major overhaul.

Hercules

Consider the engine's age, not the due date of the car.. the Renesis is about 2+ years old. After heavy driving in Japan I'm sure they can get 100k miles out of the engine.

As per the 17,000RPMs, I don't see why not either. BMW has a piston engine running at 18k now, engines which have a much lower theoretical limit because of pistons going up and down in a shaft, instead of spinning around in a rotor chamber.

Either way the redline is 9k and the max is 10k, and that should be plenty for your revving needs

Buger

If it was a one off engine, perhaps Mazda could have made a custom e-shaft that could handle the higher revs during testing?

Many people also don't know that 17,000 rpms mean that the rotors are doing 5666 rpms. I think there is definitely more power in the higher rpms but the rx-8 was tuned for a lower, more conventional rev limit (if you can call 10,000 conventional).

Brian

danger

you know what?!? that would be F*cking awesome if this news were true..

:::crosses fingers:::

rpm_pwr

and from buger:

So why build a 1-off motor for endurance testing? What are you testing then? I want to beleive this as much as you guys. I guess I've just met too many people with "17,000rpm rotaries" in my life.

-pete

Buger

Hi Pete,

I see where you are coming from but I didn't mean to imply that they made the engine differently just so that it would pass the endurance testing. The renesis engine wasn't in production though so wouldn't it have to be a one off or two off or something?

Your earlier post seemed to imply that the limiting factor was the e-shaft flex. I assumed that race engines may have different coatings, different seals, etc but the same e-shaft. A couple of questions that I have no idea about:

Are there custom e-shafts built for racing engines?
Is the e-shaft considered part of the engine?

If they did have custom e-shaft to use with thier endurance test rig, it may not test the same e-shaft flex that happens in production cars but it would certainly give very useful information on stuff like:

What is the wearability of any new coatings that they may have used on the housings?
What is the wearability of any seal built with a new material?
What is the wearability of any seal built with a new design?
How will the above new components wear with higher compression ratio of the renesis?

I'm really not trying to debate you or anything, I just try to use this board as a place to throw things out and see if I can learn something new in the process.

Peace, love, happiness and all that good stuff :p ,
Brian

twifosp

Rotaries have always been reliable. It is boost that kills em, along with any cars.

The engine itself has never really been a point of failure.

It has always been heat popping the water seals and stupid tuning.

N/A Rotaries have always been touted as extremely reliable...

Boost kills. But who cares, boost rules!!!!! I want a crate renesis for my FD once someone figures out how to put a t60 on it.

Woohoo!

RX7 Guy

rpm_pwr,

I’ve talked to dozens of racers who routinely run their stock eccentric shaft equipped 12A’s & 13B’s at 12,000 RPM’s season after season without incident. I’m not trying to incite or offend you but your comment is quite contrary to my understanding. As always, I could be wrong, perhaps the racers are guarding engine preperation secrets or something. I doubt it though as I've witnessed engines go all the way from the salvage yard to the race track so it'd be very difficult for somebody to sneak in a modified eccentric shaft past me.

I have no difficulty believing the new engine can obtain 17,000 RPM as we know that the rotors have been lightened significantly. If the weight were cut in half, the stress imparted on the eccentric shaft at 17,000 RPM would be the same as that of the original rotors at 8,500 RPM. I don’t think the weight has been cut in half but as I indicated above, I think a stock engine can sustain 12,000 RPM’s for several racing seasons. If this is true, a 33% reduction in rotor weight would allow for 18,000 RPM. (10.5 Lbs. X 12,000 RPM = 126,000 L/M) = (7.0 Lbs X 18,000 RPM = 126,000 L/M).

Technically, the weight reduction would need to be evenly distributed throughout the rotor, if it were concentrated around the center, the RPM increase would be reduced & if it were concentrated around the periphery, it would be increased. IMHO, the 17,000 isn’t only doable, it’s a logical target number.

Anyway, I’ve got 256,000 miles on my 1987 RX-7's original, un-rebuilt N/A 13B; regardless of whether the limit is 8,500, 12,000 or 17,000, they’re truly incredible pieces of engineering.





:D ADD PLENTY OF LIGHTNESS :D

Mazda man

*drool also*

threeputtwash

BMW does have piston engines going that fast, BUT it's for their F1 car, which I'm thinking costs a wee bit more than $30k

Not to mention they had reliability problems on that engine throughout this past F1 season.....

Granted a rotary is easier to spin....just a question of how fast can it spin before risking failure......

I'm thinking that 17k is a little farfetched (though I wish it was true).
I mean, if they're saying that the engine is reliable at 17k rpms, then why would they have a rev limiter set only at 9k?

cueball

A street car with 17,000 RPM would be unrealistic to most people. And it would take ages to get into the power band.

MikeW

BMW's F1 engine has a stroke somewhere between 40 and 45 mm, so @ 18000 revs, the mean piston velocity is about between 24-27 meter/sec

The M3 with its 91mm stroke coupled to its 8000 redline has a mean piston velocity of 24.2667 meter/sec

Didn't Montoya hit 19000 while qualifying for Monza?

Anyway
The stress on the internal gear would be too much for 17000 rpms.

Now if there were two internal gears, one on each side, perfectly out of phase, then maybe 17000 could be possible

rototlewski

It is not farfected at all Because when john deere had the rights to build rotarys (which were later sold to Rotary power international.) They were building concept engines for the military that could rev to 16000RPMs and that was in the 70's now mazda has been making roatrys for far longer and seems to have the most experience with them they could do this reliably. Now i can not put where I found this because it was on a thread on the www.rx7club.com site and this was awhile ago. But if john deer can do it mazda can.

rpm_pwr

what happened to my post? retype:

It's called race clearancing. You make the rotor have to reach further to contact the housings.

Maybe they know something we dont! Yes a 12a seems to have a higher limit than a 13b but I can't see a non-clearanced 13b surviving at 12,000. I've seen plenty try, none succeed (for very long). I'm not saying the engine will explode in a shower of aluminium but the most I've seen a non clearanced >10k rpm motor last is 12months and that wasnt a lot of driving.

-pete