What a great build!

 

thanks. I've been fairly discouraged with it lately. I've been trying to track down the smoking issue, and I'm closing in on a culprit. Unfortunately, I'm seeing a fair amount of oil pool in the rear rotor. Here's a look in the spark plug hole after rotating the engine (backwards) by hand. Kind of a crappy picture, but you can see all the oil that got pushed out at the bottom.



so short of a damaged oil control oring, I'm not sure what would cause this. The oil injectors are all new, although I do plan on testing them at this point. Control rings are brand new, end plates were WELL within spec per the FSM. I'd welcome other thoughts to investigate before I end up pulling the motor again.

 

ok, been a while since I've done anything on this project. I've been busy rebuilding that MB FD so it's ready to go come spring. But I'm waiting for parts, as one does, and decided to get back into this....So I bit the bullet and pulled the motor. The oil pan needs re-sealing anyways...

SOMETHING is sure wrong...I took the turbos off to get a better look inside the combustion chambers and was met with tons of oil.




A literal pool of oil in the exhaust manifold.


So I'm starting to think the turbos may be the issue, at least I'm hopeful. I don't know of any great way to bench test oil seals. The oil feed is the stock hardlines, so I'm assuming it's not over pressurizing, but even a pinched oil control seal I wouldn't think would leak like this.

My other suspicion is that the turbos may be what caused the engine to be removed from it's original host in the first place as there was a significant amount of oil deposit on the rotor faces before the rebuild. This was straight out of the engine on initial disassembly.


Thoughts anyone? Anyone know of a good way to bench test turbo oil seals?

 

I agree with ALL of that. I'm just about done completely re-wiring my FD. I used an analog PDM from Eaton to completely replace the main fuse block on the battery, the power distribution next to it that houses the EGI fuses/Fuel pump relays & that ginormous rectangular block of relays (horn/TNS/Air Pump Etc) & mounted it behind the drivers side REAR shock tower. Battery relocated & harness tucked & hidden. Like you said, why use up half-bridge outputs when the wiring is already there. Retractor relay I moved outside of the PDM as it needs to be a switching relay. Parts were obviously much cheaper, I think the unit from Waytek was about $300, then of course all the time that's needed.

 

That waterpump setup is going to be key. We really need to put our heads together for a solution that includes WP, PS, & AC

 

Have you dug deeper into this? I've encountered both engine problems, bad oil control rings, and bad turbos. How long did the engine sit before you pulled it again? If it sat for a while, then the torn/pinched part of the oil seal could be facing down causing it to drip oil into the combustion chamber. You can check your IC pipes to see if they have an oil coating inside, and you can check and see if you have oil inside your IC. If no to all of that, I would chalk up the oil in the secondaries to be pretty normal for our engines, especially since from your photos it doesn't look excessive, and would kind of shy away from a turbo issue. But since you already have the engine out, if it isn't already torn down, you can take off your LIM and see if there's anything else that you can see regarding the oil in the secondaries. If you haven't you can also see if there's excessive shaft play in the turbo. When it comes to bench testing the twins there isn't really a way to pressure test everything since everything seals with the turbo spinning. They have specific machines just for testing seals in a turbo that are way more complicated than I could possibly try and replicate at home. But all in all, if the smoke does clear after some time of idling and it doesn't smoke at all when you're driving, and based on the location of the oil that you showed sitting before the turbo in the manifold I would lean more towards a torn/pinched oil control seal in the rear rotor. That's just my 2 cents ofc.

Don't let this problem discourage you too much, you will figure it out and it will get solved, even though these issues suck to deal with. YOU'RE SO CLOSE TO HAVING THIS BEAST ON THE ROAD (As a daily driver I hope )

 

I am currently digging deeper. but it seems the more I talk to people who know what they are doing that it's more likely the oil control orings. While this is certainly not my first time rebuilding a rotary, it is always possible I botched the spring direction or something silly like that. So while the engine it out I'm going to build a fixture that holds the front half of the engine together and remove just the rear rotor and check everything. I ordered new coolant and oil control orings just to play it safe as well. Currently waiting on those to show up.

In the mean time, I opted to also address the potential turbo issue as well. I found a place that sells rebuild kits for the Hitachi HT-10 and HT-15 cartridges. In case anyone is interested this is the kit for the HT-10, and this is the kit for the HT-15.

This is my first time attempting to rebuild a turbo cartridge so we'll see how it goes. I marked the alignment of the compressor and impeller before disassembly so I don't think it'll have any issues. The rest of it is very straightforward.


More to come as I progress, but I'm doubling down on the sequential set-up as I really want a street oriented build.

 

Cool build, saw your engine bay pic on the engine bay thread.

are you planning on having AC?

And the Brian you mentioned in the thread. Is that Titanium TT Brian? He used to have or may still have nice turbo FC.

 

Yes, I'll be running an rx8 AC setup.

I think that was his old user name, but don't quote me on that. In any event the Brian I'm referring too is RogueRotaries now.

 

I'm back, and I definitely need help. I finally was able to get the rear rotor out. I made 4 braces to hold the rest of the engine in compression while I took the rear cover off in an attempt to just need to replace the rear coolant seals. It seems to be working well.


So rear rotor is exposed, and I don't see anything immediate wrong. I was semi-hoping that I had just put the oil control springs in backwards, but that doesn't appear to be the case.






orings and the control rings look fine, there's no obvious damage to them.

Housings looks ok to me. I don't see any micro cracks or anything that might leak oil


Rotor housings look ok as well.


I did notice that I must have had a bit of contamination in the oil as some point. The stationary bearing looks ok


but the rotor bearing looks a bit funny. you can't feel these, but they look like contamination of some sort to me.


Shaft looks ok-is. I didn't polish it before assembly like I probably should have. I don't see any major issues jumping out. The shaft feels very smooth still.

 

but in other news...one of the apex seal corner pieces is cracked somehow. The car has never seen boost and has hours of run time on it. Not super thrilled about this.

 

Sorry to hear the engine had to come out.
You do great work, and I know you'll get to the bottom of it.
g/l
Steve

 

Bumpin for an update! Hopefully you got her fixed up!

Im moving forward on my 3rotor build and yours is definitely something I look up to. So many cool things u did and the parts you created!

Steve

 

Guess it has been a while since I updated this. I've decided that given the critical nature of the engine, that maybe I'm better off letting an expert look over the motor. So I currently have the car at Rouge Rotaries in VT (same place it was on the dyno) where it's getting the engine, turbos and everything else checked out. It's also getting some wiring updates done to it while it's there. I'll be sure to keep y'all updated on the progress when there's anything to report.

I appreciate the high praise, and I look forward to watching your build. If you need custom parts made, let me know, I'm always up for a good challenge.

 

Hell yeah... Glad to hear! I'll be checking back for updates.

Right now, I don't have any ideas for custom parts but ill defiantly reach out to you if I do.

Steve

 

mini update!!

I spent some time up in Vermont this week with Brian trying to figure out what was going on with the oil in the engine. After some inconclusive tests trying to figure out if it was the turbos or the engine, we got a little crazy and pulled the manifolds off the turbos and mounted everything back up. Cranked the engine to build oil pressure but the starter can only get it to about 50psi. So we added a little shop air at 100 psi and the rear turbo started spewing oil out from behind the heat shield by the turbine.

Not 100% proof that this is the cause, but seems highly likely the rear turbo is (still) the problem. So now to figure out what to do with the twins....

 

Maybe adding a oil pressure regulator or a restrictor plate to the oil feed line? IDK about the Cosmo twins, but on my FC when I switched from the OEM S5 turbo to a BNR stage 3 hybrid unit, it wasn't happy with the unrestricted stock oil feed. when I got it - oil pressure/volume was overwhelming its ability to drain, so the excess oil would go up in smoke through the hot side seal. After discussing the problem with BNR, they suggested adding a restrictor plate under the oil feed flange. I just fabbed up a 1/16 inch thick piece of AL shaped like the gasket, with IIRC a 1/16" hole in the center per BNR's advice to restrict the oil flow. Been working fine since, no smoke show and the turbo isn't wearing excessively.

 

That was my first thought, but it's all the stock components for the turbos, oil feed and drains. I can't image Mazda would have made such a blunder.

 

Nothing obstructing the drain in any way? Glob of silicone or old piece of gasket? Maybe some hard oil build up on the lower side of the turbine bearing? If oil can't drain fast enough it will show some of these same symptoms and be forced out of the side seals like this. I've seen this happen when people didn't properly have a catch can or PCV setup and the build up of crankcase pressure while idling would eventually cause it to start smoking forcing oil out like this.

 

Great build! Love all the custom fab work. If you ever want a high pressure steam jet, the type jewelers use, I have one sitting around that I can’t find a use for. Might be good for cleaning parts

you sticking with the twins or going with a single at some point?

edit: not sure why I asked about the turbos. You explained your reasoning clearly earlier. All good to ignore that

 

so tiny little update. I think I've figured out why the stock turbo failed. The 20B oil pressure regulator supplies oil at around 60psi. In my infinite wisdom I thought using a higher pressure regulator from an FD would have no ill consequences. While that may have been true on turbos that were in pristine condition, I'm sure mine were not. So in an effort to remedy this, I bit the bullet and got some newly rebuilt turbos.


with a little bit of an upgrade.....The primary turbo has a new front compressor housing and rebuilt CHRA larger compressor wheel from 63mm to 70mm. Secondary turbo has a new compressor housing and larger compressor wheel from 57mm to 59mm. Also the secondary rear turbine has been clipped to improve flow. Turbo was rebuilt and balanced by Turbonetics.




In an effort to regulate pressure a bit better I've modified the oil feed banjo. with a built in orifice.


the insert was welded in.


And I put a pressure port on the top, so I can actually measure the pressure going to the turbos. In the event pressure is too low, I can bore out the orifice. Iterate until pressures look reasonable.

Fingers crossed this works!

 

turbos are in! And as a bonus I finally got the EGTs installed! Each rotor has a dedicated EGT now


Trimming of the heat shield was required, but I did retain all of them. It's a tight fit, but it all fits. here's the front and mid rotors while on engine.


and the rear with Brian at RogueRotaries deep in thought


Turbos back in place


Had to work the rear EGT around a bit, but it'll all fit

 

More minor progress. While the wiring is getting finished up I've decided to give one of these bosch tmap sensors a try. I really wanted it on the backside of the manifold, but it's so close to the firewall already, I decided to give it a little more clearance. Set-up is a little sketchy, so it was slow going.


but it turned out ok, should be nice and clean once it's wired up

 

This build is pretty legendary man. I'm still going through your other threads but good work, I know how it feels to be defeated and keep coming back. You'll get it.