PeteInLongBeach

Great topic, but the following statement just amazes me :

Eric, just what do you think the whole oil injection system is for? Why premix? What is oil for ?

I don't understand how anyone can arrive at this point of view...

DocBeech

iTrader: (1)

I think Eric is saying he does not feel that the 4 injectors placement is the reason for early failure.

olddragger

iTrader: (3)

dont forget in this is also the issue with side seal springs going bad from exposure to exhaust port heat. So the lubrication/cooling is critical in that area also. Since that is a heat failure( its thought to be that anyway) and not friction based it would take longer to show.
That is the one main difference between this engine and all the rest.
Eric knows a lot more than he is posting. Believe me.

Point for me is I am not going to trust the mop.

EricMeyer

OK guys, first off I only know what I've experienced. Our team's experience is in a race environment. Here is how I define race environment:

-5,600 to 8,700 rpm pretty much every time the car is operated on track
-1,500F+ EGT's pretty much every time the car is operated on track unless it's a yellow flag in which the EGT's are still over 1,000F
-Constant load. This is coming off the various corners in 3rd gear at 60 mph or whatever and then running wide open throttle (WOT) up through the gears to 5th or 6th at 120+ mph. Brake. Repeat process. Load, load, load, load. Basically I've got the throttle pegged at 100% for the majority of each lap for either a 15 minute qualifying session or an 8 hour enduro.
-About two dozen motors worth of rebuilds and observation
-.89 and .93 Lambda data (google if you don't know what Lambda is).
-With and without OMP function
-Various amounts of premix
-Lots of data collection
-The greatest number of hours we've seen is 25 as after that our power slowly falls off (side seal spring).

When running in the above environment WITHOUT the OMP function we have experienced huge, huge, side seal spring failure. Huge. Please note that I did not use the word "Apex" anywhere in the previous sentence. We've had newly refreshed motors last 6 hours. We've had refreshed motors last 2 hours. Side seal spring failure with no OMP function.

This has been my experience and leads me to MY THEORY of the coorelation of OMP to the #1 failure mode of the engines (which was the original post of this thread). To my knowledge (and I could be totally off here), the failure mode that leads to low compression that leads to warranty rebuilds at Mazdas facility in Virginia has to do with carbon buildup in and around the apex seal groove which prevents apex seal travel which restricts the apex sealing function which causes compression loss which leads to low power and/or inability to start the car. And I could be way wrong here but this is my understanding.

Apex seal wear is (according to all the smart RACE engine guys I've talked to) is actually much more of a rotor housing wear which is caused by the bowing of the center of the apex seal during its normal function and this over time wears a groove in the softer aluminum housings and this makes for an escape or compression leakage. This is very much like a scored piston engine cylinder bore which lets compression escape around the rings. This groove decreases the engines ability to retain higher compression and therefore higher power.

Again, I could be wrong and our experience with the OMP has and does have a huge coorelation to side seal spring failure. Not apex seal or corner seal. At all. We've been reusing the stock apex seals for a lonnnng time. We've also tried ceramics and they last so damn long its crazy (in our operating environment).

It would appear that the new S2 oiling location to the Apex seal area (not pointed only to the side irons) is to address something specifically with the apex seal function. I would suggest this is an effort to both lubricate, reduce friction and reduce heat (the beneficial byproducts of lubrication). I would feel confident in saying that this is to reduce wear and friction of the apex seal to the rotor housing, reduce the rate of housing wear and therefore give the engine a longer ability to make higher compression.

Now......isn't this different than gummed up Apex seals? It is my understanding that the gummed up apex seals are the main reason why the street motors end up in warranty. Pulling a poorly combustionable motor oil from the engine and then trying to burn it in a combustiion process leads to some nasty, nasty, nasty deposits. Two stroke oil is preferred----why? Because it has better combustion properties. Why don't people premix with motor oil? Because there is a better product for this. The motor oil deposited via the S1 side irons lubricates but also leaves a nasty residue which gums up sealing grooves. A seal needs to freely travel to operate properly. We have replaced our source of lubricant to a remote reservoir and use two stroke oil and the resultant deposits are much less. They're still there but they are much less.

If one were to dissconnect the side iron lubrication function of the S2 motors and retain the new apex seal squirter location (using or not using premix) I'll suggest to everyone that the failure mode of these engines would still be side seal springs. Which is the basis of my theory of what the S1 OMP was designed for----prevent side seal friction/spring failure----not to reduce apex seal wear.

In summary, I don't think the S1 OMP function was to address apex seal wear. It was to address side seal spring/seal wear. Again, this has been our experience under our operating parameters. Perhaps long term street wear is different.

I was hoping that someone who has cracked open many, many, many high mileage engines could clarify this. It is pretty common knowledge that when replacing apex seals one should also strongly consider replacing the rotor housings too. Why? Because they have been grooved or scored. Just about every engine builder I know will demand new rotor housings to start with and I hope people think about that for a bit. Even if the initial failure modes are apex seal wear related, that does not overrule (IMO) that function of the OMP is for Apex seals. Removal of the OMP toasts the side seal/side seal spring function and this is the hands down weak link of the motor without OMP.

I believe the only people who can add value to this theory are those who have seen numerous high mileage street engine teardowns and I encourage everyone to abstain from comment or speculation until they can contribute their findings of RENESIS high mileage failure. Speculation and "my brother in law opened one of these one time and he told me XYZ" is what we don't need right now. Neither is 3rd party here say.

Brian, can you comment here?
Paul, can you comment here?

I'm sure other qualified engine builders are much more well versed than I on this and apologies in advance for not mentioned you if you've got a ton of experience in this field.

Cheers, and always looking to learn something.

See you at the track.

Eric

9krpmrx8

iTrader: (46)

Edit:

Thanks Eric, I was expecting a post like that. I am patiently awaiting responses like this and was hoping Brian, Paul, Charles, RR, MM, RG, etc. would post up for an educated discussion on the topic. You may be exactly right. I am off to read

olddragger

iTrader: (3)

Nice Eric. You see guys, Eric is one fellow that has invested a lot of money and time in racing this car. He has experienced and learned a LOT. True his enviroment is a little different but some of the basic principles are still relavate. We are fortunate to have Eric with the years of working with this engine who doesnt mind freely posting what he has seen. Most professtional racers of the rotary engine will not do that. I understand why they dont and thats cool. I have said it before and i will say it angain---Thanks Eric.
Once compression starts going down in this engine--then thats it. Doesnt matter which way it starts. The difference between us street guys and Eric is this. A 10 hp lost to us is hardly noticeable, to Eric its a lost race. So he is on top of things wayyyyy before we notice anything.

I have another thread going on in which i wondered why the engine coolant has a double pass design and not a single pass. Thinking a single pass coolant system would offer more cooling to the exhaust port area. Presently the coolant only picks up between 10-16F as it passes the exhaust ports. On a single pass system it would pick up double that?
This is relavate because of exactly what Eric is saying. The side seal spring. The lubrication that is provided is not enough to adequtely cool it. Then take into account what the OP is saying and you have a possible very volatile situation. I have no idea if a single pass system could even be built but I too enjoy talking about things.

I do need a sohn adaptor--just havnt gotten around to it.

The carbon issue is well known--it is one thing my water meth system helps with but everyone cant run that.
Dont forget also that the gas we burn (and who knows what it is now a days) leaves more carbon than the oil--so be as careful as you can with your choice. You can steam clean the engine every week if you want to.
I plan on calling Swain tech to see if their valve sping coating could possible help with our side seal springs. Our springs are pretty small so they may not be able to help.
But good discussions and I am enjoying this thread.

MazdaManiac

iTrader: (3)

Through cooling.

shadycrew31

iTrader: (6)

Also from what I found my side seals had shrunk, not sure the cause of this. Most of my side seals had a gap large enough to slide another side seal into.

Again I had little damage to my apex seals. I did have low compression mostly due to carbon build up on the corner seals and side seal shrinkage.

9krpmrx8

iTrader: (46)

I never got a chance to tear apart my two previous motors but when this one fails It will be documented. But both the previous engines died in the same fashion, which was power loss and eventually constant stalling.

EricMeyer

Never really figured out why with the data. The EGT's dropped an honest 25F+ with the addition of the OMP. Sometimes it looks like about a 40F reduction. 25F for certain.

At .93L and no OMP we were seeing 1,700F and 1,600F sustained. Lowering to .89 (and still no OMP) we dropped about 100F. Still saw the side seal spring deterioration (wear witness marks on the peaks and valleys) to the point where the spring(s) no longer performed their original function. Taken to a more extreme measure and continuing to push the car even though I knew it was down on power, the springs would get thinner and thinner and thinner (again, no OMP and either Lambda). You could get them to break and the side seal would cantilever and clip a port. Havoc central.

About a year ago I was headed into our shop and it was raining outside. Had the wipes on. Pulled into the shop and turned the car off. Started it back up a few hours later and the wipers were still on from the rain outside. The rubber blades made that terrible screeching sound because the windshield was dry. Then it hit me. This has to be the same thing that was happening in the motor. No lubrication. Super hot and that side seal was just skipping right along there the entire time. This would explain the spring witness marks because that seal was oscillating. Bouncing up and down and up and down in 1,600F weather. I recall seeing something for the first time with the irons that many a smart builder had yet to discover. They had discovered the side seal spring thickness (hard to measure the thickness deltas) but none of us had ever seen want amounted to little bouncing screech marks on the irons. Couldn't feel them. The light was just right and I could see something. Added the OMP the next day and got 20 hours on that motor with less than 1% power loss. 22 hours and she was about 5 rwhp down. Yanked the motor. Tore it down. Saw the beginnings of seal spring wear. Everything else was cherry. Working on the second motor to duplicate the results. My gut is saying that the WOT environment and the heat is a big contributing factor. I betcha if we fattened her up a ton we could get these things to live longer. A friend runs his at .85 and gets about 40 hours he offers (racing environment).

If it were legal to try some stuff in our series I would but the cost of testing is crazy nuts. We get about 3 honest hours on a set of tires racing up front and that goes for about a grand. The new Pirelli's slicks are $1,300 and go away after 2 cycles and/or 1 hour. The cost for a half a season of motor testing is crazy, crazy.

Have a great weekend everyone. Headed to the shop to break in a new motor on the dyno, yank it and put it on the trailer.

E

MazdaManiac

iTrader: (3)

Going leaner than that ~.90 Lambda is going to give up a LOT of power in your application.
I don't think that lowering the EGTs is going to survive that spring much longer than what you are experiencing.
I've gone on and on about the OMP's primary function being cooling the stuff that sees exhaust ports, so I don't think I need to do that again here.
The side seal springs, I believe, are not failing just from the heat, though. Have you measured the change in the side seal length on the motors that failed the springs? How about a change in form of the corner seals?

I'd love to see the side seal springs made out of stainless.

ASH8

And "How" much Oil does a functioning EMOP system actually use?.

Over two years of ownership, 40,000 KMS, I can virtually set my watch to the quantity of Engine Oil I use.

Metric measurements.

1000 Mil per 5000 Kilometres of distance traveled ( I use the same 1 Litre bottle (1000 mils) of engine oil for top off which lasts 5000 KMS, my Service intervals ).

Break that up into a single kilometre, that is 0.20 of a mil per kilometre. (1000 Metres).

That is then (in my case, S2) divided into 6 Nozzles, that is just over 0.03 of a Mil per Injector Nozzle...minute.

To put it into some perspective 0.20 of a mil of Fluid to look at is approximately the size of a DIME, your smallest coin.. that amount of oil is then divided into 6 Nozzles...per 1000 metres or a Kilometre.

Naturally, I am NOT suggesting that my PCM/EMOP's injects this quantity Every Kilometre I drive, I have just used this to get some perspective on how little OIL is used in Mazda latest MOP arrangement.

It could inject 1 mil every 5 or 6 Kilometres or 3.5 Miles, too many variants, BUT, I am pretty sure the ON and then OFF period of the EMOP's is consistently the same cycle time of about 1.5 seconds, I don't think it is Variable or longer, but it could be., I get the 1.5 seconds from when I hear EMOP's run at every engine Turn OFF.

Which is very little Engine Oil 'Injected' into Apex and Corner Seal for LUBRICATION...let alone real "Cooling".

Another reason why I Pre-mix, as I don't believe Mazda have got the amount of oil "injected" right...IMO

To suggest is has nothing to do with Lubrication is just ludicrous.

ASH8

Side Seal SPRINGS were Modified by Mazda from 1st February, 2009 Production...now Pink paint coded.

Anyone know the Physical Difference from original Blue Painted ones.??..

Apart from that No further changes to engine Internals, as of December 2010.

EricMeyer

Never measured corner seal height (or other). Tried side seal clearance from 2 to 20 thou total w/no differences in power or life. The spring has been and continues to be the achilles heel for us. Reduce the spring fail rate and engine life goes up.

Open to more ideas. I'll start measuring corner seals. Honestly the spring has been the issue. I would have to think that the actual rotor temps are below 300F and its that dang hot exh gas reeking havoc. Any idea MM of how that exhaust gas is influencing the side seal in its groove? Additionally, the area of weak spring has no rhyme or reason to WHERE it fails. Sometimes 1 spring on the front rotor. Sometime a rear. Sometime the rotor face toward the center iron, another time not. Sometime the spring breaks near the corner seal or in the center or on the other end of the spring. Weird. In all cases it breaks where it is thinnest (which I'm sure you know but share for others).

olddragger

iTrader: (3)

Ash-- does seem like very little lube doesnt it? But little is better than none. On the track I can use 1/4 quart in one session (approx 50 miles?) and that is with S1 OEM mop settings. That is reasonable I believe. On the street--- i know what you mean--doesnt seem like enough at all.
I do wonder if the actual side seal spring has basically changed with that new part number?
Are there any S2 engines on the track now?

Does pre mixing really doesnt get to the side seals well?

With the side port design it would seem that having the oil nozzles built into the irons would be better? They could be positioned in a more avantaeous way so the oil itself would not be subjected to the combustion process as much? I have never understood Mazda's placement of the nozzles--but what do I know?

Does the renesis have more rotor wobble than earlier types? Or does the new side seal shape put more stress on the springs in combo with the increased heat?
Who was it that was trying ceramix corner seals?

dang i sure ask a lot of questions.
are we there yet.
OD

9krpmrx8

iTrader: (46)

So I assume 09' + springs were changed for a reason. I wonder what those differences are and I will have to keep that in mind when it's time for me to rebuild.

MazdaManiac

iTrader: (3)

I meant after the tear-down. How much had they changed in length?

Your example is in this context is, unfortunately, completely useless.
You are averaging which tells us nothing.
How about actually measuring OMP consumption by throttle opening angle per mile?

New Yorker

As much as I'd like to know why a small percentage of stock Renesis engines fail, I'd more like to know why most Renesis engines don't fail. If there's an Achilles heel in the design, why is it not affecting most — if not all — of the Renesis engines out there? What are so many RX-8 owners around the world doing right? Why is it that a handful of RX-8 owners have such bad luck while most of us (and I include, of course, the many RX-8 owners who never make their way to this website) enjoy our cars without any particular engine problems to speak of? If most engines perform a certain way, why do some fail to? What is difference between the "failed engines" and the many more "non-failed" engines out there? If they are mechanically the same, that suggests that the culprit lies in the way they are maintained or used.

MazdaManiac

iTrader: (3)

It is actually affecting nearly all of the RX-8s ever sold.
If you take the total number of engines that have been replaced under warranty and expand that to include the people that replaced the engine on their own (without Mazda's assitance) and those that continue to drive the car in a sub-optimal state, you will come to a number that is nearly equal to the total number of RX-8s sold, minus all the cars that have gone to the wreckers or on to alternate lives.
It hot climates (where the heating effect is exacerbated), you will not be able to find more than a small handful of examples where the engine hasn't been replaced.

New Yorker

Fascinating. Would you be kind enough to share the raw numbers you base this on, please. Thanks!

9krpmrx8

iTrader: (46)

Geesh, I don't want to go off topic but...

What do you consider a small percentage? I mean they built an entire engine building facility to accommodate the demand and contracted out with CAT as well. Not to mention my dealer (largest volume privately owned mazda dealer in the US) has done a few hundred and counting. That is one dealership in a city of 5 Mazda dealers.

There is a reason you rarely see RX8's with over 100k on the original engine. And as MM eluded to, many owners are probably driving around with damaged motors without even knowing it.

You have made your opinion known before on this topic. There is no raw data because Mazda would never release that. But we have a local member who is a tech at that dealer and I know some current and past service guys. You THINK the number of replacements is low, your engine is still running fine, we get it. Now back on topic.

New Yorker

All well and good, except for one tiny fact (don't you hate those?): Renesis failures are the exception. Most Renesis engines don't fail. Most Renesis engines have not been replaced. I can't believe how you use classic, anecdotal evidence to refute that. After all, this is an important matter.

The underlying premise here — that all Renesis engines suffer from a faulty design that dooms them to failure — is a theory that runs contrary to the facts. I'm not saying your theory isn't correct; it may well be. But it's mere conjecture, and it doesn't explain the fact that every day, around the world, thousands of Renesis engines are humming along just fine, not in need of replacement. Many of them have logged high mileage; some of them even belong to the tiny percentage of RX-8 owners who post on this website.

That's all.

9krpmrx8

iTrader: (46)

Well this this isn't the thread to discuss this so please move along if you do not have anything to provide. Now back on topic. Does anyone know of any aftermarket side seal springs? I also read that Mazdaspeed Motor-sports has coated springs but could not find anything on the site.

DocBeech

iTrader: (1)

you would have to ask them after your a member.

SARRAS

Actually... that point may only hold up in the US - where your fuel is quite poor compared to other Western countries. In Australia, which is equally hot in places, there is not a chronic engine failure issue - but then we can easily access 95 Ron and 98 Ron gasoline. Of course they do fail here - but its nothing like MOST fail. So that could be a factor, the other one being that our cars have only one oil cooler - pointing to the low oil pressure issue that has been discussed when two coolers are present in conjunction with the factory oil pressure nozzles.

However, I still lean towards fuel quality as a basic cause - because there's another engine that has a massive fail rate in the US - the V6 in the Nissan / Infinity G35 series. That engine also had a bad fail rate and a factory rebuild program for the 2003 / 2004 / 2005 models. I looked into those cars here quite extensively as I was going to get one of them before I found my RX, and the bottom line here is that the Nissan V6, on our 98 Ron fuel, has no particularly prominent fail rate. So by comparison....

One last interesting point - there's a sticker inside our fuel flaps that states" "Minimum 95 RON" which is a couple of points higher than the best US gasoline - seems to be a clue there.