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corner seal springs are the most sensitive tells as to heat. while the 3 are not super flattened they do seem lower and it would be a reasonable speculation that they came from the rear rotor corner piece end of the apex seal. (as i am sure you and others have concluded)
flattened corner seal springs can reduce comp 30%. normally the much much hotter condition from knock is what flattens the springs.
being repititive to underscore importance:
do not build your motor w any corner seal springs but OE FD/inconel. the shiny springs you normally get from Atkins are not inconel.
the corner pieces on the rear rotor were out of position on assembly. they were not glued to the apex seal and the spring pushed them away at an angle. when the plates were torqued together the corners were pinched. this misalignment is also confirmed by the missing adjoining chrome on the housings. corner pieces on apex seals should always be glued. the misalignment is probably what caused your apex seal degradation.
your rotor housings should be honed. recommend Adam at REC. confirm your corner seal springs are the real deal (inconel OE FD) and at least .17 high. simple to measure w vernier caliper, change plugs. (see my new Spark Plug Section re a new plug for the trail position), add AI and get tuning.
Thanks for the spark plug recommendation Howard. Do you have a recommendation for the leading plugs? I assume heat range of 10 for Op's setup would be sufficient?
Originally Posted by Howard Coleman
corner seal springs are the most sensitive tells as to heat. while the 3 are not super flattened they do seem lower and it would be a reasonable speculation that they came from the rear rotor corner piece end of the apex seal. (as i am sure you and others have concluded)
flattened corner seal springs can reduce comp 30%. normally the much much hotter condition from knock is what flattens the springs.
being repititive to underscore importance:
do not build your motor w any corner seal springs but OE FD/inconel. the shiny springs you normally get from Atkins are not inconel.
always glue the apex seal corner piece
Atkins states these are Inconel? Maybe they updated these last since your experience with them? Reason I bring this up is because I have an Atkins rebuild kit on the way. I can confirm if the OEM NF01 springs are included in the kit vs an "ARE" part number.
Just to be on the safe side, order by part number from a place that wont sell replacements as OEM. Ray Crowe, local dealer, online vendor, etc, make sure they are OEM.
the first corner seal springs on the page are listed as '74-'11 ARE85 $48
further down the page are the FD springs, Atkins P/N ARE13 $63. these are the ones you want. Mazda P/N is NF0-11-C24
Atkins also sells engine closing kits and i note in both options the good corner seal springs are included. Good on Atkins.
i do prefer OE corner seals to Atkins as they are chromed/less drag. Atkins are not. when Goopy decided to make corner seals they eventually decided to not proceed as the chrome process turned out to be too expensive.
Just some housekeeping on some comments with my replies..... again, thank you everyone for your input, truly appreciate the conversation this is bringing forward.
Originally Posted by Howard Coleman
the corner pieces on the rear rotor were out of position on assembly. they were not glued to the apex seal and the spring pushed them away at an angle. when the plates were torqued together the corners were pinched. this misalignment is also confirmed by the missing adjoining chrome on the housings. corner pieces on apex seals should always be glued. the misalignment is probably what caused your apex seal degradation.
your rotor housings should be honed. recommend Adam at REC. confirm your corner seal springs are the real deal (inconel OE FD) and at least .17 high. simple to measure w vernier caliper, change plugs. (see my new Spark Plug Section re a new plug for the trail position), add AI and get tuning.
I will measure mine with a caliper, likely I will replace all of these springs regardless. In regards to REC, I am fortunate enough that they are essentially local to me (3hr drive down the highway). I have a set of the NGK 7420-10's (was planning to use in all 4 spots) but was using the BUR9s just for break-in. The intent was to swap the 7420's in when I introduced boost but referring back to my initial post, spark plugs were fouling so damn fast I didn't want to ruin the very expensive plugs until I figured out if that was just from being excessively rich. Does the condition of my spark plugs help to conclude at all about the apex seal misalignment?
In regards to tuning, I am using someone that I trust fully and have nothing but good experience with. Now although I don't trust myself enough to do the tuning on my own (even though I created my own initial first start and break-in tune successfully), I do have enough knowledge in this area (and am familiar enough with the ECU and it's software) to at least follow along with my tuner and understand what he is doing, with the ability to make certain changes if required .
Originally Posted by gdub29e
Late to the party but wanted to say that’s a great looking setup. Looks like you found the issue. It’s unfortunate that happened. One of the first motors I put together I pinched a corner seal and the corner piece resulting in a noticeable compression issue between two chambers. Unfortunately, I did not catch it and everything was completely installed. I had to disassemble. Lesson learned . Just remember that sometimes learning comes at a cost. Don’t get discouraged.
~ GW
PS ; Howard’s link is most intriguing. I’m running mid 400s with r7420-10s. I plan to investigate this trailing plug this Spring.
Thank you! Just as an FYI, I did not build this engine; but I did do the teardown and will be rebuilding it myself (with the help of my good friend @FFR818 ) which will be my first experience of this; so appreciate you passing on these hard learned experiences. This swap project as a whole as been filled with these tough lessons, and I've come a LONG way in the past 3 years because of it.
Originally Posted by FFR818
But if this was the case, how did he have 120psi compression for at least the first 1000kms when we checked it?
Honestly, I'm having a hard time visualizing what Howard is mentioning above too for this same reason. I would have expected it to show up during break-in, but admittedly have only 1 engine worth of break-in experience to draw from. I was getting up to 8000RPM prior to introducing boost; and I'd have to look back through my records of when I last saw really good compression and how that correlates to where I had redline set to. It may be that I didn't compression test between raising redline to 8000 and introducing boost. I was doing regular compression tests for the first 1500 or so kms. Once I kept getting improved compression as break-in kms rose I sort of stopped worrying about this so much and wasn't comp testing anymore. Cold tests started around 95-100PSI then rose up to 120+ during no boost, 4500RPM redline break-in.
Originally Posted by Fickert
Is this anything of significance? Noticeably lower than the rest. Not sure if you have these labeled where they came from.
Unfortunately they are not labeled as to where they came from (other than the 6 on the right should be from rear rotor); but as Howard mentions it's seems fair to assume where those 3 came from. I will give these a good measure with a caliper and see what the actual height difference is.
Originally Posted by Howard Coleman
corner seal springs are the most sensitive tells as to heat. while the 3 are not super flattened they do seem lower and it would be a reasonable speculation that they came from the rear rotor corner piece end of the apex seal. (as i am sure you and others have concluded)
flattened corner seal springs can reduce comp 30%. normally the much much hotter condition from knock is what flattens the springs.
being repititive to underscore importance:
do not build your motor w any corner seal springs but OE FD/inconel. the shiny springs you normally get from Atkins are not inconel.
always glue the apex seal corner piece
Dually noted, thanks again for your advice! The plan has always been to use stock FD seals/springs apart from aftermarket Apex seals. For this rebuild I already have a few things lined up that should be for the better. This includes, Turblown studs, Xcessive LIM, sealed tip EGT probes with stand-alone gauge, E&J Apex seals. Want to look into race clearancing my rotors and getting a full blown dynamic balance of the rotating assembly done (all services REC can offer). Will need to still do some homework on AI systems/setup. My initial thoughts are that I should be safe getting this engine set up to 10 or 12 PSI prior to adding AI? My thoughts are just one less system to have to worry about until I get the engine running properly on it's own, even if that means holding back more boost. The intent of this project is for a reliable weekend street driven application. Would love to take it out to the odd track lapping event but that will be a significantly small portion of it's actual driving time.
Last edited by RotaryMachineRx; 01-09-23 at 12:10 PM.
I also had badly tapered Apex Seal wear with I-Rotary seals. Curious are you running OEM Tension bolts or studs?
Hey Ryan (we met briefly at Conroy's event in Red Deer this summer); this was with stock tension bolts. I didn't notice anything out of the ordinary with the tension bolts; but I haven't thought to look at those really at all any closer. My assessment of those right now is strictly derived from the fact that they came out of the engine without any resistance which really doesn't say anything at all lol. Going hand in hand with the tension bolts, I haven't looked the factory dowels over at all either.
Last edited by RotaryMachineRx; 01-09-23 at 03:57 PM.
i have never seen such a mismatch re apex seals. based on the condition of the crown of the seals and lack of heat related blueing i highly doubt the height differential ocurred while in the motor.
please measure and post the height of your corner seal springs for each of the rotors.
i may have missed it but didn't see AI? heat is the primary challenge of any single turbo rotary. AI is one of the necessary components needed to deal w heat. cold spark plugs are another requirement. 9s shouldn't even be in a break in single turbo app.
if you look at the close side of the rear rotor exhaust port you will see an inordinate amount of carbon. at the close, two thirds of your apex seal isn't touching the housing.
i can't tell if the rotor housing longitudinal striations are grooves or oil traces. do they feel bumpy when you run your fingernail over them laterally?
i do think you have more than one thing going on in your motor and you will need to fix all of the items. please post a pic of your front rotor housing exhaust port.
Are these suggestions specifically for high-power applications?
A single turbo that's making more modest levels of power should actually have less of a heat issue than stock twins running similar boost, I would think.
I've done a bunch of track days on 9s without so much as premix and not had any issues, but I am running relatively low levels of boost.
Of course, the gas is 98-100 octane here...
(I am on 10s now....)
I took my engine to REC in Calgary and went over everything with Adam. Like most here, he doesn't have a solid explanation for the lopsided apex seal wear; he's seen it twice before and cannot say what the cause is. In his opinion my side seals and oil control rings were used before going into this engine and in their current form are definitely garbage. The rear iron was in need of lapping but other than that the rest of the engine looked healthy enough to be reused in the rebuild. I left the engine with him for media blasting (I don't have it back with me yet) but prior to visiting REC the previous engine builder offered to clean up my rotor 2 housing. It came out looking brand new and after inspection at REC also passes the test for reusability. While the engine is at REC I also opted for dynamic balancing, and a race clearance on the rotors.
Need to let my bank account recuperate for now and then I'll be buying all new rotor springs/seals along with new oil control rings and an engine overhaul kit (all the soft seals/gaskets) in another month or so. Should also note that I locked my caliper to 3/16" and all my existing corner seals made contact with the caliper, so appears they are all still within spec.
Currently on my bench I have a new set of Turblown studs, E&J apex seals, an EGT gauge/probes, and a serial cable to connect my AEM UEGO to my Adaptronic so I can bypass the crappy internal WB module. I'll start doing this wiring to install the new electronics in the next couple weeks. I've also included below some photos, another couple of the Apex seal wear using the E&J apex seal tool I received from Edgar.
Rotor 2 housing as it came out of engine:
Rotor 2 housing after clean up (don't mind the grease marks, that's just from me handling it):
Rotor 1 Apex seals as they came out of engine:
Rotor 2 Apex seals as they came out of engine (they are measuring 0.8 mm difference in height from the assist piece side to the solid side!!):
Last edited by RotaryMachineRx; 02-02-23 at 07:06 PM.
Also need to note that my fuel injectors were flow tested and cleaned and there was nothing of significance there. All injectors were within spec and within 50cc’s of each other.
Also have an Xcessive LIM ordered through IRP which is of course on back order so hopefully that doesn’t hold me up too long.
Yup, don't want to talk too much about it in this thread, there is a dedicated thread full of bitterness for IRP (much of it rightfully so) you can go there for that, but Xcessive spent the better part of last year retooling their shop which is why there was so much backlog for these. Spoke with IRP and my understanding is that this backlog is being cleared by Xcessive now. If you could show me somewhere else that is selling them and has them in stock I'd happily look there but in my searching that place doesn't exists. So I placed my order about a month ago with IRP in hopes I would receive it within a few months of the order and it wouldn't hold up my April/May plan to fire this car back up.
Last edited by RotaryMachineRx; 02-03-23 at 03:47 PM.
Agree. Don't want to muddy up this thread. I hope you get what you ordered in a reasonable amount of time. If it were me, I'd wait till it was in stock to pay instead of being treated like a bank. Excessive sells parts directly, they don't even have it on their site anymore. I need one and will wait until it shows back up on their website and buy it.
Because as stated; it’s not even listed on the Xcessive website anymore and everybody and their brother is looking for one.
.
I ordered it from IRP mid July 2022 and received it the first week of October.
It wasn’t listed on Xcessive’s website then either and every other site had it listed for $200 more and on back order. When I ordered it, IRP had it listed as “in stock” but shortly after it changed to back order and was told that mine was back ordered as well. But I did get it.
Engine received back from REC. Rear iron needed to be lapped, other than than the rest was cleaned up and is good to go. Got dynamic balancing of the rotating assembly and a race clearance done while it was there as well:
Just a short update of where I'm at. Planning to pick away at rotor assembly at nights throughout this week so I can be ready to assemble the short block on Saturday
Engine rebuild went smoothly and overall was a great success. I had one front cover bolt strip (the bolt threads stripped not the front plate threads) that I still need to address as well as pressure testing the coolant passages. Other than that I'm just waiting on my Xcessive LIM before bolting the long block together and getting it back in the car.
Rotor assembly and side seal clearancing went well with my ranges varying from .002 to .0035" (spec is .002 to .006"). Stacking the engine went smoothly and problem free, end float was measured afterwards and landed somewhere around ~.00225 - .0025" (spec is .0016 - .0027").
Just to recap engine mods consist of large street port, clearanced rotors, E&J Apex seals, and turblown stud kit.
Smooth, resistance free, spinning of the engine with solid and beautiful sounding pulses. Very, very happy with the final outcome, easy to say that my first time engine build was a huge success!
Small update on my self-rebuild here. Engine is very close to going back into the chassis, decided to get the LIM and Turbine housing ceramic coated while it was all out. Going to install fuel rails then smoke test the engine while it's on the stand, make sure I have no intake or exhaust manifold leaks on the parts that require the engine out of the chassis to service (LIM mainly). Other than that will bolt on CAS/Trigger wheel, water pump, pulley's, oil filter adapter, and a few other misc items then get this back into the car!
For the longest time I was staring at the hose going to a block, thinking "Did he install the oil feed wrong?" only to realize it's a water-cooled turbo. lol.
Not in the intake if that's what you're implying . The nut is not on there as I have a standard M8 nut on there as the domed style nut didn't fit back there against my firewall in the Rx8 chassis with stock LIM. The hopes are that with the 1/2" or so gained from the firewall by using the Xcessive LIM now I will have more room for the appropriate nut. Also yes, I did tape the LIM to prevent anything from dropping in after taking these photos.
01-09-23 | 07:59 AM
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. Just remember that sometimes learning comes at a cost. Don’t get discouraged.
. The nut is not on there as I have a standard M8 nut on there as the domed style nut didn't fit back there against my firewall in the Rx8 chassis with stock LIM. The hopes are that with the 1/2" or so gained from the firewall by using the Xcessive LIM now I will have more room for the appropriate nut. Also yes, I did tape the LIM to prevent anything from dropping in after taking these photos.