3 pcs Apex seal
 

Can anyone tell me which year/years Mazda used 3 pcs seals?

I believe only the fd's and 3 rotors had 3 piece apex's but I could be wrong!

they started with the Series 4 cars and i think Mazda had phased them out sometime during the Series 5 run - definitely before the FD came on the scene. while i can't say for sure, i doubt any JC Cosmo engine (13B or 20B) came with them.

yup that sounds correct

early 13b in the rotory pick up also used a three piece apex seal

Thanks guys, I just opened up a supposedly 1991 Series 5 Tll engine and find this three pcs apex seals, nothing broken and the side and rotor housings in good shape, except a minor corrosion mark in the bottom of one side housing. I also noticed that the rotor housing doesn’t have the imprint:
Mazda Motor Corp.
Hiroshima Japan
License NSU- Wankel
My old (Series 5)!? have these imprints on the top of the housing
Also the c/c measurement between the spark plugs differ, the new one 49 m.m. (1.930) and the old one 53 m.m. (2.087). Can someone enlightening me what I am working on, Please.

incorrect, all early mazda's used 2 piece seals including the original 13B engines from '73-77. all early engines between 1973 and 1985 had 3mm seals, no 3mm seal was ever produced in 3 pieces. prior to that carbon 6mm single piece seals were prevalent, but at a cost of life expectancy.

the ONLY cars that ever had 3 piece seals were every single FC/FD to roll off the assembly line from 1985 through 2002.

mazda discontinued the 3 piece seals right about the time the renesis was developed in 2003. mazda now only sells 2 piece seals even for the engines they made originally with the 3 piece seals as an alternate part.

3 piece seals are garbage, do not look for them and do not install them. many engines failed prematurely due to them. most later series remanufactured FC/FD engines got the alternate 2 piece seals due to reduced failure rates, as the 3 piece seals would also carbon lock much easier, causing a no start condition.


the wider gap between the spark plugs is USDM series 5 and JDM series 4. series 4 USDM engines were the only engines to have the narrowed gap between the plugs. you likely have an S5 rebuilt with series 4 rotor housings. series 5 rotors have a machined rotor compression pocket, if yours are cast then you in fact have a series 4 engine, maybe with some series 5 bits bolts onto it but a series 4 keg nonetheless.

Thank you very much Rotary Evolution, you are the man, my 74 year old brain are now spinning faster than a rotary engine on full boost.
This engine was supposed to be pulled out of a -91 Tll automatic trans. Right side steering wheel car. According to Rotary Performance I Garland TX. (Probably not a direct import to USA)
The rotors are machined, i.e. series 5 and also lighter than the series 4 rotors. Also the front cover got more meat around the oil inlet and the return oil inlet from the turbo closer to the center of the cover compared to the old BDC build that Acroy posted for me before I became a member.
Seems that I now got a worn out S5 engine with S5 rotor housing and S4 rotors and a S5 engine with S4 rotor housing and S5 rotors!!??
The engine have been opened as the silicone around the oil pan was over flowing everywhere but no other evidence, I assume that Mazda paint the hardware, this one have no paint.
Anyhow, I am happy with engine as everything is within specification. Now I need some guidance how to rebuild. I use the car for road racing and 1 mile speed racing.
I got Himni Racing FC V2 T04R 9 (T67) Turbo Kit, HR V2 3” SS downpipe, TiAL 44 mm MVR Ext. wastegate, GReddy boost controller, GReddy Intercooler, TurboXS type H-RFL blow-off valve, Halteck E6K, Snow Performance Stage 2 Water/Meth. Kit, AEM fuel pressure regulator and parallel fuel lines, Bosch 044 pump, 720 cc/min. primary and 1680 cc/min injectors.
The old BDC 2004 build engine run 455 whp at 18 psi. on this setup before it went south…
I am aiming at ca 400 whp at 14-15 psi with streetporting, Am I dreaming or is it possible?
I am looking for the best apex and corner seals money can buy for this application, as I like to drive a few more years….. Please help :lol:

My 89 TII had the 3 piece seals

if it does in fact have S4 turbo rotors it will be a little more difficult to make your target, the engine will also spool a little slower than a proper S5 turbo engine would. you could find a set of S5 rotors, front and rear counterweight and use those in your build.

for the apex seals i have had great success with Goopy Performance apex seals. i know many people on here push rotary aviation and ALS so i am in the minority in experience with them but i have never broken, bent or damaged a set yet in a several years and pushing them upwards of 500whp in street driven applications(not a phenominal figure but the west coast doesn't have all that many monster builds to claim much higher reliability so far..). the other upside is they offer many different size seals beyond the standard 2mm and 3mm variants for worn rotor seal slots.

if you decide you want to try them let me know, i offer them at a slight discount over their list price which is cheaper than the ALS seals.

one example of an S4 TII w/8.5:1 w/414 whp @ 15 psi. and that's breathing thru the factory AFM:

https://www.rx7club.com/time-slips-d...-s360-1018017/

.

Thank you guys for good information’s, This is my first rebuild on a rotary, so I have decided to take a conservative approach and use OEM parts this time. I hope it will not come back and bite me. The old motor I disassembled had aviation Apex and Corner seals and really ate the crap out of rotor housings and side housings. Made me gun shy about aftermarket stuff. I am keeping the old housings for now, waiting for somebody to start re-chroming business….. anyhow, I will keep your posted….. Thanks

3 piece apex seals are awesome for scraping the gunk out of the apex seal slots during a rebuild...and that's about it!

curious. was this engine babied during the 1st 1K miles or so? OMP + premix from the start?

I have no idea, I am the third owner after the rebuilt in 2004. No OMP only Premix, I have used Idemitsu premix 1,5 oz/Gal. and 104-109 octane gas. Only used for road racing and 1 mile speed racing 25 times in 5 years.

Primary Diffuser
 

A new question, I just came across primary bottom diffusers on my new engine (FC5 T ll), the old BDC rebuilt engine did not have any. Is this an oversight or should I delete the same after street porting?
I assume that they are there to create turbulence?

they're there to atomize the fuel more efficiently than the injectors alone can accomplish. they're not absolutely necessary but when possible i prefer to keep them. some injectors won't fit with the stock diffusers so it really just depends on the setup.

Lets say I have RC injectors or any modern type injector with a excellent spray pattern. Would removing them or cutting the diffuser part out be a good idea since the stock injectors are no longer being used?

that would be a difficult one to answer. the diffusers are for old type injectors so newer units like ID or EV14's probably would not need them.

OK, sorry to be such an airhead, the primary injectors I have are Denso 95500-0830, according to the motor specification I got with the Car, calls for 720cc/min. Should I use diffuser? Also the top rubber gasket (not the O-ring, is hard and cracked) is it preferable to get new fresh injectors than get part for the old ones?

you can get the spacer from most injector shops, mazda, mazdatrix and a few other sources. the 720's are older injectors so i would use the diffusers.

note, w/no OMP, Racing beat suggests over 4 oz per gal pre-mix on turbo's w/600 hp.:
Rotary Tech Tips: Oil Filters & Metering Oil Pump

you're much braver than i am using 2 piece 2mm OEM apex seals on a 400+ whp application. but i guess w/104-109 octane greatly reduces the chance of grenading.

I do not consider myself very brave (maybe sometimes on the track), building an engine very conservative (I think). Most experts seem to agree that it is better to run softer seals and save the housings. I am also taking the advice to run more premix, consider 3 oz./gal, maybe more during brakein !!??

i don't necessarily agree that softer seals will save the housings but they will not break. i have seen less wear from more brittle materials like the OEM seals than the softer seals.

note that i'm not saying the softer seals will destroy a housing but they may cause some lateral striations that will need to be cleaned up during another rebuild. the good thing about the indestructable seals is the engines will not leave you stranded or destroy more expensive parts where the more brittle seals will most definitely kill the rotor and a housing to unusable limits.

there has never been an easy answer as to which route to take but with people destroying rotors continuously eventually turbo parts will be as rare to find as good 12A housings. with softer seals at least you still have something left to work with at the end of the day. going forward we won't have many options like in the past with the FB's/old schools using FC/FD parts, we have the 13B-MSP(renesis) which is a horrible platform for turboing due to its extreme compression and lack of a peripheral exhaust port(when a seal goes in one of those engines the devastation is horrible because nothing can readily escape the engine).

i have seen the striations from every type of seal however(even OEM seals can cause it), no definitive cause as to why. foreign debris or lack of internal seal lubrication is generally the accepted cause. some seal alloys probably cause it more readily than others as well, but with every seal material being proprietary and secretive no one can really know. ceramic and carbon seals being the only exception to the rule but they are only ideal for non force inducted engines and specific applications.