David,

Thanks for putting some perspective on this.

Cheers,
Hymee.

PS - For those who have decided they are now going to fire-sale their RX-8 because of this... if it really is true you might not be able to. If it isn't true, someone is going to get a bargain.

 

David,

Thanks for some real world hard driving numbers. Also, great job in Ohio on your ST win!

P.S. Do you use dino or synthetic oil?

 

Maybe we should ask MAZDA head office for a reply to this situation
.Before unnecessarely panicking rx8 owners .

cheers
michael

 

Do you think they might sue those responsible for spreading rumors?

So before I comment any further, or anyone else for that matter... I'll get a compression test done. My car has done ~35,000 km which is >21,500 miles. Still going strong as far as I am concerned.

I think we should wait and see the results of a diverse set of results before we judge. Don't forget CZ had bearing failures - did that mean they are all duds? No.

Cheers,
Hymee.

 

Bingo Hymee... you hit on exactly what I was thinking on both points... what %-age of engines are seeing this problem of premature failure of the side and corner seals and unless you have some solid evidence, Mazda will NOT be happy to hear this... think about the beginning of all this conversations and draw your own conclusions.

 

So ahhh...the renesis has a problem with the seals, and it just so happens that our annonymous visitor has the fix for it, for the right amount of money I'm guessing?

I'm going to take this one with a grain of salt, until I hear of other owners complaining of low compression at 15,000+ miles. If it's for real, how in the world would Mazda miss something so obvious?

 

amen.

besides, whats a 10%loss if it's torbo'd or super'd. Car is still gonna perfom great.

 

i seem to have 12,000 miles on mine and it feels as strong as ever (~196rwhp a few months ago)... one engine does not make a serious design problem

 

My question is how does the opening point of the pirts have anything to do with the side seals crashing into the closing edge. The closing timing is the same as the old 6 port engines and those didn't have this problem. The only concern about the opening side being over too far is with the corner seals falling into the ports. That's it. This is where the Renesis ports are larger. They open earlier. They don't close later. Oh the large streetported 13B 4 port engines, this problem would occur. This was because the open area of the port was so great that more of the side seals were unsupported than supported as they passed over this point. However, the 6 port engines have the small bridge of housing between the secondary and auxillary ports that can hold up the side seals adequately. If this were removed like many foolish 2nd generation RX-7 people do, then side seals could be an issue.

I am not going to claim it is impossible since someone has found this to be the case on their engine but I am not going to just panic based off of one experience and say that all of the 6 port RX-8 engines are doomed. I'd really like to see the pictures to study them. I know it is an easy mod (assuming your engine is apart) to help fix this issue. Why isn't this an issue on the old 6 port engines? It has to do with the closing timing not the opening timing and these are the same as the old engines. I don't get it.

All engines will lose a little power over their life. Race engines see it faster because most of their life is at a higher rpm under much harsher loads. 3-4% for every 25-30 hours of race time is more like several years of street time. Don't worry about it.

 

I think it is when the oil pressure gauge comes in handy.

OK I have seen this in the RX-7 mag talking about overhalling.

RX-7 needs a overhall when,
Idling getting gradually rough.
Harder to start car.
Losing oil pressure.
Excessive oil usage/consumption.
Losing turbo boost.
Poor fuel ecomony.

~ this makes so much sense. ~ although most are common sense

BTW I think checking the compression via WDS is a good idea

 

lol no way. A disconnected map sensor of vacuum leak will give you those problems and you can still have good oil pressure readings and no compression.

WTF?

 

Kind of shocking to find sideseal and corner seal wear so premature. I also hoped that Mazda would pick up on this problem from testing for durability. This problem effects many high performance engine builders when they are porting an engine larger then stock form. The renesis engine has an intake port opening larger then my streetport template that I currently sell for FD turbo engines and that template is not a mild port.

Porting a renesis engine and tapering or folding over the closing edge of the ports to a smooth and not so sharp edge will in return give reliability and durability to the engine. I have seen Mazda tried to address the closing edge of the ports by making the port timing a bit later by the closing edge of the intake port but the sideseals are still getting shorter and shorter as the engine is putting on miles and miles.

I'm sure Mazda will figure out a way to protect sideseals and corner seals from premature wear but for now porting and polishing in a proper way will take care of this problem. I'll address porting and polishing and horsepower as I go along.

 

What's really strange is that if you swap Renesis rotors into a 13B and use the Renesis corner seals, they will absolutely eat up the 13B side housings! How hard are the Renesis housings?

 

Dude, he just asked a question. That's it. He wasn't being an ***. That could have been addressed in a much more polite manner.

 

If you taper the edge, don't you lose vaccuum worse than just wearing the side seals? I guess it would depend on the degree of the taper, but i could see how rubbing constantly against an unpolished port would cause side seal wear. If the edge was rough, it'd wear quickly, but if the edge was tapered too much, wouldnt it cause a break in pressure?

 

I feel is based on total milage. I felt my hard driving was a contribution to my large sideseal gap but talking to my friend he basically said normal milage will wear the seal down regardless. I don't want to speculate as far as lost of power or emmisions from 247 to 238 but When the engine is assembled to a, for example .002 of and inch sideseal to all cornerseals gap of the rotor, that engine will land for example 247hp, after that .002 gap grows to .010 and larger after break in that same engine will dyno 238hp. My engine went from 188whp to 170whp loosing exactly 18 extra horses. Now the sideseal gap I had was .018 to .020 thousands of and inch that is insane.. I have clearanced engines to .003 and torn down the engine a year later and found sideseal to cornerseal gap at a respectable .004 to .005.. sideseal wear is perfectly normal on a rotary engine from is normal rotating design but not so premature.

 

I have taking pictures of my findings and I'll post pics with info so many members that are visual could understand exactly what is going on and pics of my ported engine with my "fix the problem mod"

 

Good information you bring here but i have documented info. with pics showing my findings and I also have talked to somebody in the field that confirmed the durability issue. I think I'm not supposed to talk..

 

Big Dave, thanks for bringing some reality and semblance to this thread.

 

The Renesis was in development for years. I'm sure Mazda tested numerous engines, running them for the equivalent of 100,000 miles or more before releasing the final production RX-8. While there very well may be a problem with some of the engines, it's hard to imagine that it's a general problem with all of them.

I hope Mr. P&P continues his research and continues to offer his insight and suggestions to the forum. I also think we should wait for more info before we all go jumping off bridges.

 

This thread will NOT turn into a disgusting display like the last one, so here's the bottom line, either you post information in a respectful manner, or keep your mouth shut. Mugatu and Mazda Maniac, one more time trying to start **** and you're gone. I deleted a ton of posts, sorry if I deleted a good one ... but I was just trying to reset the thread back to a point where it was still just information sharing.

While I may not entirely agree with the thread starter, he's only posting his experience. There are people on here with a lot more RENESIS experience than the thread starter, and they have not reported any similar issues. Also, the RENESIS has been used in Star Mazda races all year, and the engine is rock solid in that series.

So while I don't think one persons experience proves that Mazda has a problem, he does have a right to post here. So if you just want to talk ****, go over to nopistons ... they'll welcome you with open arms.

 

There are a few post missing from this thread...? There is no problem with the seals, this is maybe a problem with this one engine...

 

No point here for me to continue. I'll finish with saying power gains are respectable with the renesis engine after some mods are done.

 

My question is how much $$$$ for this mod if/when this problem comes into question?

 

From what I got from the thread the seals will gradually wear over time and will need to be replaced in the future. That's almost normal from what I know about the rotary engine, it just means we need to know when to have these tolerances checked. The problem was exaggerated when you ported and polished the engine but the performance gains are substantial. Great, at least we have that knowledge in case we decide to try this option and we can buy a multitude of seals to keep the engine running strong. Thanks for your contribution Mr. P&P and fell free to P/M me if you make any more big gains, even if you don't have a dyno sheet at hand. Your work may bring problems, but for every problem there is a solution.