I have a street ported single turbo 3rd gen. I run it with a power FC and my fuel sys is 550cc pri 1680 cc sec with nippon fuel pump (supra TT). also SX FPR. My issue is i have had several motors fail with less then 1k miles on them. most are babied until i hit the dyno for tuning then the motor seems to lose vaccum at idle and compression on every pull under boost. slightly but it loses vaccum. say 4 inches in 10-15 pulls. The car starts to sound like a harley and once the motor is torn down the apex seals are damaged. The seals are rounded off and overheated. this seems to always be the front rotor seals severly and the rear rotor seals mildly damaged. The car is always tuned on a dyno by either Demitrious of reactive racing or Steve Kan of gotham racing (formerly Rotary performance mechanic). The same problem has arised from the last 3 motors. the motors were rebuilt not replaced. all the housings and rotors were inspected by my engine builder and all seals were replaced and the motor was reinstalled. The car generates decent compression under break in driving (no boost) but once it hit the dyno it will fail like clockwork. Also i run very conservative air fuels in the low to mid 10's have replaced my secondarie inj and had pri flow tested and cleaned by rc engineering. Also I have verified timing ing with a light intake temps get no higher then 40-50 degrees C coolant temps in the low 90's fuel pressure is verified by a gauge on the regulator. boost didnt even exceed 13.8 psi on the last dyno tuning session and it still failed. the fuel pressure was 52 lbs at 12.5 psi. the plugs are NGK9's platinums all around new before every tuning session. The tuner pulled the plugs after almost every pull! The front rotor plugs get more damage then the rears and the tuner adds fuel to the front but it doesnt seem to help much. even with Air /fuels in the 10'conservative timing and the apex seals get damaged by what looks like overheating. they warp or bend but never break. Stock mazda 2mm seals. We have tried the 2 and 3 piece with no difference. the car even has a new wiring harness. I am out of ideas. Please comment. Here is a list of my mods



JR's Rotary Large Streetport Race Spec'd 2mm mazda seals,(NEW), A-SPEC GT3540 Dual ball Bearing Single Turbo, Fluidyne radiator, 3 BAR MAP, Greddy2 Row R-spec core FMIC, Miata Battery, Supra FP, SX FPR, 1680cc Inj, HKS Twin Power Ign. Apexi Power FC w/ Commander, Defi Boost gauge and White Gauge faces, ACT 6 Puck unsprung clutch with ACT HD Pressure plate, Mazdatrix short shifter, Redline fuid, Blitz SBC-ID boost controller, Greddy Underdrive pully. Ceramic coated 4 inch custom DP, ATR SS Midpipe, Greddy SP catback, 18 inch Volk TE-37's with Bridgestone S-03's. Bilstein HD's with HKS Super sport springs. Strut tower brace, Rotor Sports Racing Urethane Engine mounts and sway bar bushings.

Good air/fuels, good fuel pressure, good temps, good timing...not a whole lot left after that point. What are your tuners and engine builders saying?

I have witnessed two of Mike's motors fail and want to add a few things that I think will be helpful when examining his problem



Before the last dyno tuning session the following was replaced

-main wiring harness -brand new harness installed

-secondary injectors and resistors

-primary injectors cleaned and flow tested

-ground strap to upper intake manifold

-negative connection to battery

-plugs





As Mike said after one pull on the dyno and some part throttle time we shut the car down and pulled the plugs to inspect. The front plugs were slightly white, but generally dark and the rears were dark. Steve added 5% more fuel to the front by adjusting the front primary injector. After another pull we re examined the plugs and found that we overcompensated. Eventually steve reduced the fuel increase to 2% and from this point on, for the rest of the day, both plugs looked even and were both damp after runs.



Steve knows the history of Mike's motors and for that reason was not tuning for power; timing and AFRs were very conservative. Knowing exactly the way Mike's previous two motors failed I checked idle vac after each run. Initially it was around 355 on the pfc. It started dropping when we got to around 11psi. From this point on we started losing about 10 points of vac after each run. At no point was there detonation of any kind.

Here is a pic of one of Mike's apex seals out of the 4th or 5th motor-which failed with the same symptoms.

How long had those cleaned injectors sat around for before they put into the car?

So is the edge that seats against the rotor housing rounded?

These are new rotors too? I guess if you've tried 2 and 3mm seals there isn't any play for them to move around.

tuners dont know, basically grasping at straws, engine builder is one of the better builders and hasnt ever seen this either. The only other things may be internal due to the same problem arising from same reused housings. I need to consult the engine builder for specifics of the build. The tuner thought the rotor housing exhaust port could cause a seals to fail but i would know for sure if that was the issue unless i replaced the housings with new ones. Can an oil metering failure cause this type of damage/heat to plugs and seals? car does not break up. no detonation. its run rich into low 10's and as high as mid 11's on different rebuilds and all with same result. no more then 15-16 degrees of advance

JR's as in Ito built your motor?

burn outline

YES and discolored like from lean/heat but widebands show rich, 3 different widebands have verified this at different sessions.

maybe a day or two

did you bevel the exhaust ports?

If the porting was done wrong it would cause that edge to be rounded. But if

JRs is Ito's shop then thats not even a possibility.

Well its has to be either bad housings or bad porting. What else woulc cause that rounding?

You ask about the the OMP failing. I am hoping your premixing. I doubt this is your main problem but it could be contributing to it.



you should run 8 oz. of premix per tankful.

We're not sure if mike's exhaust ports were bevelled, we'll have to talk to the builder about it.



This is something the tuners asked about also. Please elaborate on the effect that not beveling would have. The leading edge of mike's seals have a slight convex curve to them on the sections that are outside the exhaust ports. The part of the seal that passes over the exhaust port does not have the same convex shape. Instead the curve seems to have been worn down so that top of the seal comes to a point with two straight sides rather than an overall arc.



Non exhaust port area shape:

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Exhaust port area shape:

<span style='font-size:14pt;line-height:100%'>></span>



In the last photo I attacked you can make out where the two planes ( / and \ ) come to a point. The each face (symbolized by a "/" in the previous sentence) of the point is black in color. By contrast the area where the two planes meet is silver in color and at the same height as the center of the convex curve for the edge of the seal that does not pass over the exhaust port.



Bear in mind that the difference is extremely subtle, but then again all these motors had less than 2,000 miles on them.

Well it does appear the oil injection is working as you can see where it is clean in the center of the burned apex seal. And yes you should be premixing.

Does it look like this? or does the apex seal hit a sharp flat edge?



https://www.nopistons.com/forums/upl...1071187191.jpg

We're not sure. We're thinking of using a medical scope to see if we can catch a glimpse of the seals through the exhaust port. If we are able get access to the equipment we'll check out the port edge too.

Just got back from NYC/LI.....



Hey Mike,

Sorry that the motor isn't working again. I'm clueless as to why the engine keeps eating up apex seals. For those that are curious about this, here're some findings I notice on his car.



First, I don't think there was any fuel issues with the car since we verified the spark plugs almost every 3-4 pulls (reclean them before putting back in). On the first couple of pulls where I dial the a/f in so that I could barely see it register on the wideband. After we pulled the spark plugs out, we notice a very minor color difference with front and rear plugs (not even very noticable unless you looked at it very closely). Knowing mike's engine has suffer melting front apex seals, I decided to richen up the primary injector by 8% (2.7% overall in total fuel). We made 2-3 more pulls (a/f ratio was below 10 where we couldn't even register). Pulle the plugs back out and saw that the front was richer than the rear, I then lean out the front offset to 5% over the rear (1.8% overall in total fuel), make a few pull and then recheck the plugs. It was still running rich, so the final offset adjustment ended to be 2% (.7% more than the rear). Which is negligible (if you think about it). Now that we know both front and rear offset is dial in, we then slowly lean out the a/f to try to tune it out. I tried to tune his car to around 10.5:1 because of mike's past engine history. There was a few times where it the a/f hit 10.7-10.8 but not many time has it get close to 11:1 a/f ratio. As we started to make more pull, the engine vacuum started to drop. It wasn't much noticable at 11psi but when we slowly turning the boost up, the vacuum drop was definately noticable and was evident that the issue still exist. We pulled the plugs out again to check, everything seems fine and shows signs off running rich. The only thing I could really think off is the exhaust port or the shape of the port causing it to run higher EGT than normal. I couldn't verify that w/o knowing what the port looks like but after looking at the worn out apex seals (after the tuning), it seems like that it couldn't have been caused by lean a/f ratio but rather very high EGT at the manifold or the exit of the port. I wish we could have made another pull on the dyno to see how hot the exhaust manifold. Also the turbine wheel and see if there are any abnormal wear caused by extreme thermal conditions.

could maybe be something wired like a bent e shaft?

what would the side effects of that cause? I am looking into any and all possibilities. I have replaced most items that could cause such a failure that i know of. I will ask the engine builder what else to look for but i wanted to get some opinions from here to start me off.

Sounds like a good suspect

If his e-shaft was bent, he wouldn't get past 500 miles. You'd know if your motor was blown due to a bent e-shaft. It would sound like a diesel(clunk, ka-clunk, ka-clunk, ka-clunk) and as soon as took the oil pan off...bronze fairy dust everywhere. https://www.nopistons.com/forums/pub...IR#>/blink.png

im not a rotary engine builder or expert... but for the edge to be sharp as described... something must have been eating it.... so most likely the exhaust port like i stated before https://www.nopistons.com/forums/pub...IR#>/smile.png

I am no expert either. this motor has been taken apart 3 times and has been inspected for damage, all parts. The engine builder took a real good look this last time and didn't notice any damage. Checked all parts, inspected closely and reassembled with new seals. The car was pulling good vaccum -14 inches as we strapped it too the rollers. I had almost 1k miles on it of very careful driving, no high rpms, no or very little boost. Idled perfectly. Even after closely scutinizing the air/fuels and the timing, fuel pressure and boost levels. the motor slowly started to lose vaccum. we were goin so slow it took us 3 hours on the dyno just to get it up to 13+ psi. There wasn't anything we could see to show why we were losing vaccum at idle. Because this has happened 3x before I knew the signs, I heard the car start to sound like a chopper and the vaccum drop to -10 inches. We stopped there so it would still start and drive until it got sorted out. I had apex seals with me from the previous motors and these are what you see here. I have more pics i took, I hope they show more detail. I have confidence in my engine builder that he will eventually work this out. Sometimes its a slow process. Has anyone ever heard of this happening before?

Another front rotor seal.

seal # 2, 3

A good shot of the 'ridge.'

thanks for shaving the pics to fit chris

Im no expert, I've only rebuilt 1 motor. But I would check all the parts that stayed constant in all the failures. Stationary gears? Rotors, especially the apex seal groove clearance? You have problly already checked these but Im just tryin to help out.

I hope you figure it out man. Keep us updated.

You still haven't told us who built the motor.

i believe Ito did.

right now we are looking at all possabilities. Right now I would like to test the oil metering jets/sprayers to see if they are clogged. I have been racking my brain tryin to figure this out. I talked to the engine builder and he has some ideas. I will keep the thread posted once some things are investigated further.

What are these ideas of his?

Things like apex seal spring pressure, injector spray patterns etc. Very preliminary

anyone have info about oil metering pump failures and oil sprayer failures and the results? Oil cooler failure or tstat failures for oil cooler?

looks like everyone is hiding. I am now putting EGT gauges in both runners before the turbo in the Exhaust manifold. Also swapping out the ECU and goin to put a timing light on it under WOT on the dyno and track the timing and see where it goes. Alsp thinking about taking off 3 ohm resitors. This has been mentioned to me and i am toying with the idea.

typical oil metering failures would be stuff like: apex seals and housings wear fast, ive seen one that was great on one rotor, but the rotor with the metering failure had chips in the rotor housing chrome.



if the oil is too hot i think you're gonna see things like: failed rotor oil seals/ o rings. apex seals will be worn on the sides (not the tip so much). maybe detonation? remember oil too hot = rotor too hot. maybe some oddbal bearing wear, but i think that would show up if you really cooked it



maybe an oil temp guage would be good? racing beat recommends oil temp going into the motor should never go over 210f. they are very conservative about temps.

Ok had Steve Kan make me a test map for the PFC and while on the phone with Demitrious we checked the timing with a light and with a linear timing map ran the motor up to 7krpms in neutral. The timing was solid all the way through. it didnt jump around or move. It stayed right where the map was. So it rules out there being an issue with timing wandering or doing something funky under rpms with either interfearance or Ign amplifier causing an issue.



I am ordering a manifold from Sean at A-spectuning in chicago with 2 EGT;s 1 in each runner BEFORE the turbo. This will give me accurate EGT temps to further trouble shoot. So far the Fuel and the timing have been verified to be stable and performing properly. Also a Guy named RUSS in Florida is having a similar issue with his motor. He has a GT40R turbo with a T4 flange. So the backpressure theory doesnt seem to fit. His rear rotor seals are seeing the significant damage while my front apex seals are seeing the brunt of it. This is interesting and makes me wonder why its reversed. He has a new ported motor from Pettit Racing mine is from JR's Rotary Performance.



Russ is also seeing his crankcase getting pressurized by cumbustion pressure and like mine causing oil to spray out of the dipstick. This has happened to me on my last 2 rebuilds of the same motor. He is having his motor torn down by pettit and I am curious to see if these motors have the same issues Internally with the apex seals damage.