nah.

I kinda "assume" that there is a very tiny little small leak inside my engine. Cuz from time to time I see some oily residue inside the coolant overflow tank. and I "don't" think those came from the coolant itself.

but my engine works fine, typical compression, just a bit hotter than "usual" ... might have something to do with me living in NYC and I think Im living @ around sea level so ... -_-

Back on topic, RR, does my compression numbers sound fine for a 46K engine with 20K premixing ? -_-

 

RotaryRessurection,

You mention that the water pump experiences cavitation at high RPMs. Is this the sound I hear at 6000+ RPM's that is coming from my glovebox and sounds like somebody is pouring plastic BB's onto a table? My old water cooled PC made a similar sound when some air bubbles ran through the heater core.

 

must stay on track here--dont want to get into discussion on engine temps ---we have other threads for that---sorry.
OD

 

Ok, since no one answered question #2, then I want to ask if there are pics of high mileage 13b apex seals with or without premix showing even wear?

Once again, this is important empirical evidence of whatever hypothesis. Frankly, I'm surprised that no one has done this already on this forum.

 

No need. Mazda already "gave us" the proof.

09+ Model Renesis has an extra nozzle at the center of the housing to spray oil.

 

I'm still amazed that a rotary engine can put out as much twist as it does when looking at that little eccentric shaft. It just doesn't appear to give the rotors much mechanical advantage. Truly an amazing engine.

Thanks for the great pictures.

-1.3L

 

You need to replace or rebuild your engine.

The following table work of an engineer (IOANNIS www.rx8forum.gr) indicates that your rotor1 is out of mazda specs. In addition Rotor 2 seems to be at the margin. The table was prepared according to Mazda compression graph on the workshop manual

 

https://www.rx8club.com/showthread.p...rbles+in+a+can

Long thread. Happy readings.

 

Ok so didn't the 13b already have the center nozzle? What do long mileage 13b apex seals look like? The visual data must be out there and lots of it, right?

Secondly, even with the center nozzle for the 2009, all 3 nozzles are letting out less oil than in the 13b presumably, so that visual data will take some time to produce.

Which leads me back to the 13b data. What do those seals look like? Someone here must know and must have seen what they tend to look like. With and without premix.

 

Actually, the 13B and older rotaries did have a single center nozzle but only a single nozzle. With the side exhaust ports on the Renesis they added a second nozzle but both nozzles were aimed at the sides of the apex seals and the hot exhaust gasses, leaving the center apex seals underlubricated. Initially, the amount of oil was also kept at a minimum in the Renesis, perhaps to help with emissions and cat longevity. Later flashes have increased the amount of oil injected. Initial reports of oil consumption on the '09 seem to indicate that perhaps even more oil is now being injected so I wouldn't assume that it is a lower overall amount. Visual evidence indicates worse center apex seal wear on the Renesis than the earlier 13B.

 

Thats what I've been thinking. Cuz at 280 something RPM I should be getting something higher than what I got.

Hmm, but they said my engine is still within spec. it was done @ Wayne Mazda. Maybe I should go back and ask again. Cuz from time to time my engine might just "die" at stop light. Its rare, but it did happened to me more than 20 times this year (Im positive about the number. lol. I love my car so much)

I thought Mazda updated their spec again? calling something like under 6 point something = fail. (instead of 7. something)

but I dont know.

RR. any ideas ?

 

Interesting. So the 13b only had a single center nozzle, I never knew that. Which means the critical experiment is actually the current 2009, which we'll then have to wait a while for the data. Damn.

Did the 13b apex seals wear more on the outsides?

 

No, the data is already in. Mazda wouldna't have added the center nozzle back if it wasn't needed. That's what nycgps was trying to explain to you by saying that Mazda already "gave us" the proof.

 

Just saw your added question. Yes, but not as much and this was not as critical on peripheral port engines.

 

numbers are low but acceptable. multiply the mazda test numbers by 14.2 to obtain psi numbers. 96 is the mazda lower limit, under that and you should be awarded a new engine under warranty. Older rotaries would continue to run fairly well into the 80's, but the rx8 fuel injection system must not be as tolerant of weak compression thus they have drawn the line higher.

100-110 is fairly healthy, 110-120 is great, 120+ is like-new.

 

the waterpump makes no noise. you are either hearing an exhaust leak of some sort or a pinging condition in the engine (which is cause for immediate concern).

 

in reply to your question...no one has seen fit to buy a brand new car and then start modifying it by disabling the OMP and running premix. I would love to see the results of such too. But no one has ever done it to my knowledge.

Rx7 engines that have been rebuilt with new parts, and then run with dedicated premix, and later torn down (with relatively low mileage) you see very little wear. Problem is, the people that do this mod, are usually those who more intensively modify their car. Thus the engine in it's modified form usually does not stay together for more than 50k miles before being torn apart for a repair, refresh, porting, or otherwise change of setup.

You are surprised that no one has taken a brand new $25,000 dollar car and started modifying it from day one in such a way as to void the warranty, drove it 100k miles, THEN torn it down for an examination, all for the peace of mind of people on an internet forum? Think about what you are saying for a moment. Many people here are lucky to even GET the car, much less to do the sort of testing and evaluation you are talking about. Not many people here even have the knowledge necessary to do so, much less the money or time.

 

this bothers the hell out of me.

THE RENESIS IS A 13B. EVERY NORTH AMERICAN PRODUCTION ROTARY SINCE 1986 HAS BEEN A 13B. IT IS STAMPED RIGHT ON TOP.

Now, with that said.

Older 13b rotaries had a single nozzle in each housing. On those you saw the inverse of what you see on renesis engines. On the older ones, you saw not much wear in the center, and more wear on the edges. So the apex seal looked like ( when it had 100k on it.

Now in the renesis you have 2 injectors per housing, one on each end, nothing in the center, and the seals look like ) with 100k on them.

The result of both is the same...blowby and low compression.

With the 09+ with 3 injectors per housing, it will look better. Maybe still not perfect, but certainly better. Only time will tell.

 

cranking rpm spec for comp test is 250rpm. IF you crank test lower than that, the comp number results will be slightly lower. Higher cranking, higher comp numbers. There is a sliding scale for this adjustment in the mazda factory manuals for rx7s, not sure about the 8. Same for altitude...higher altitude, lower comp numbers are acceptable.

Cranking at 280 you should be seeing some very strong compression numbers. Your numbers are already borderline. IF you were seeing standard cranking rpm of 250 your numbers would probably drop even further.

IF you are under warranty you should be given a new engine in my opinion. If you are not, then run it until it breaks, or until the car becomes undriveable, and then go for a rebuild out of pocket. As my 90psi 117k mile engine here showed, just because you drop below mazda's magical compression theshold does not mean your engine is BLOWN. It means it is weak, and some cars may experience problems in idling and power. Rotaries can continue to run well into the 85psi range before the car begins to become undriveable (won't restart reliably).

 

OOPS, SORRY.

 

Thx for answering

When I first saw the results, I was a bit skeptical, but they said it was ok

But then from time to time my motor would stall at red light so.....

I have to go back there next week or something to fix my parking brake handle and tailpipe anyway. Gonna ask them

Thx a lot RR. Happy thanksgiving