hi, i just tore down my first rotary and the housings have some wear and i was wondering if they were still usable. they came out of a 90 na fc and the irons and rotors look fine. im on a small budget and don't plan to turbo or push and real power im just wanting it to run reliably. that being said on the edges they have some long wear marks i can get my fingernails on and look pretty scary. are these still usable and/or do i need to do anything to make sure it doesn't get worse?

 

Chrome flaking is pretty common on nearly any used engine now adays. I believe the Mazda spec for useable rebuild parts is less than 3mm. If it measures out OK, you'll be fine to use.

 

i was also wondering after cleaning everything, i have some heat marks on the e shaft and was wondering if that’s normal? i added some pictures below.
thanks!

 

That e-shaft looks beautiful! As for that heat mark that you see, that's completely normal. Last year, I purchased a brand-new FD e-shaft for my FC S5 engine build, and that new shaft has those same "heat marks". Must be part of the manufacturing process.Those rotor bearing journals look perfect. As for the rotor housings...They may be usable, but you should consider how many more miles that they would have on them, and that they are going to produce reduced compression. Look in to purchasing new rotor housings if you can. I know they are getting dreadfully expensive, but if you plan on keeping the car the rest of your life, new housings will provide you with many years and miles of service with optimum performance.

 

I'd say the heat marks are part of the heat treatment of the E shaft. Probably a "localized" treating for the journal and bearing areas which later are ground to size and finish.

 

thanks! i’m glad that’s normal. at the moment i really just want the car to get running so i can drive it. im planning on buying a second turbo engine to build out for more power later when i have more time and money. so id like to use the housings if i can unless they would last less than a year or two.
thanks!

edit,
since it is better to get nicer housings, as long as i use the whole s5 rotating assembly, could i use s4 housings with s5 irons? just straight swap the s5 housings for s4. i have a line for some s4 housings that are pretty cheap and in great condition so if that worked i might run that if it doesn't mess something up.
thanks!

 

In my current understanding, I do believe you could use S4 housings with an S5 rotating assembly and irons. The only problem that I could see is with emissions functionality. I think that S4 housings have a different EGR setup than S5. If emissions functionality is not a concern, then they probably would work. I am going to be using turbo rotor housings in my new S5 engine build as recommended by Atkins Rotary, since emissions is not an issue with my antique-registered RX-7 in my state. I recently started another thread to ask if FD rotor housings would work in an S5 build, since they can be found for sale as a pair, (front and rear), on e-bay for under $1400 for the pair...That's less than $700 each! If I get a reply, I'll let you know since you can not find individual brand-new S5 rotor housings for that price anymore.

 

Look into the distance from leading to trailing spark plug holes for s4 vs s5 housings. I know they are different on t2, not sure about na or if it matters as much on na engines.

 

According to WJM Rotaries in Melbourne, Australia, using FD rotor housings in an FC S4 or S5 build is entirely possible. As an added benefit, the exhaust ports are larger for additional power gain. Emissions compatibility would still be an issue. There is an interesting pattern of needing to upgrade to various FD and even RX-8 parts in order to build or rebuild our S4 or S5 N/A engines. Within the inventory of parts for my build, I am using new FC S5 rotors and side housings, S5 rear turbo rotor housings, FD front counterweight and front stack parts, a FD eccentric shaft, (and due to this e-shaft and its slightly different oil hole locations), RX-8 high power front and rear stationary gears!

 

These are not bad enough to be a problem. There are big chips out of some housings I've seen at the edge. i doubt these are a problem and should produce good compression.