I just bought a 90 dollar Rx7 13B S4 NA Non turbo engine...but it was flooded and has a a lot of rust...and the iron plates are non usable..but the rotors and e-shaft looks like can still be used.

I also have an Rx8 engine from a customer that failed due to oil starvation and the bearings spun from the rotors making the rotors and e-shaft non usable

Now Im thinking if i can use the S4 NA rotors + e-shaft and counterweights in ang Rx8 engine without any problems?

Thanks

 

As long as you use the whole rotating assembly. It'll be slower since the compression ratio is going to drop. Was that RX8 engine Auto or Manual?

 

NO. The non RX-8 rotors do not have the "scraper" rings that sit between the oil rings and the side seals. The exhaust ports will cook the oil control O-rings probably before the coolant is warmed up on the first start.

IIRC, you should be able to use the RX-7 eccentric shaft in the RX-8 engine, and bearings are not really very difficult to swap in rotors. Grind the locator tab off of the new bearings (it does nothing useful) and smear red Loctite in the rotor before pressing the new bearing in.

 

Thanks for the reply...hmm didnt think of that...due to the transfer of the exhaust ports to the side iron plates
Problem with the Rx8 rotors is that the metal where the bearing sits is already scraped, inserting a new bearing will not be a guaranteed even fitting even if we use the red loctite

 

Goopy should have oversized bearings for spun rotors. maybe you can look into it.

 

just cut the make peri exhaust ports with your rx8 housings.

 

Can this be done? Transfer of exhaust sleeve from my 13B S4 NA? What will i do with the original exhaust ports? Close it with a steel plate? Have anyone done this before? Thanks

 

Thanks Ill check it out

 

can it done? sure.

have others done it? sure.

so far i have not seen anyone use the older sleeves in the MSP housings, but i would imagine anything is possible if you go to right machinist. the ones i've seen so far just build a whole new aluminum insert that makes the housing flush (i'm guessing so it seals better against the manifold). as for the original ports, it's your choice whether you want to seal them off or keep them active.

if it's something you're interested in, then you can ask Goopy about it as well.

 

I thought Renesis ports opened too early for older 13B rotors to the point that the leading tip of the side seal would be caught. Anyone know for sure?
I have traced a Renesis port over a TII:



I've also read the shorter Renesis apex seals aren't suited to the usual peripheral port opening size but maybe if they were supported in the center like this old "honeycomb" port:

 

Hmmm ...maybe I should shift to this combo...
Use my extra 13B S4 or S5 Turbo 2 iron side plates instead + 13B S4 Non turbo rotors? This is a better combo? Pros and cons? Thanks

 

you're absolutely right. i'm not sure how i missed the original post in all of this, but yeah ... the older rotors will not work with MSP side housings. that's why they moved the side seal locations on the rotors. the MSP are like a giant streetport from the factory, except they modified the rotors to fit.

this is true as well, but most people simply cut the Renesis apex seal slots to use older 13B seals.

 

sounds like all you need are rotor housings.

what exactly is your goal?

 

I just want to play with a non turbo rotary engine...using my extra S4 NA rotors

I have an extra S4 Turbo and S5 Turbo engine...all dismantled already. My extra 13B-MSP is already out of the combination due to discussed mismatch

The iron plates of the S4 NA cannot be used already since its a water flooded engine and the plates all have water corrosion marks so deep that will surely eat the rotor seals away

So what combination can I use?

Rotors from the 13B NA S4 High comp
Iron plates from (S4 turbo or S5 turbo)? which is better for Non turbo use even though they originally came from a Turbo rotary engine
Rotor housings from (S4 turbo or S5 turbo)?
Intake manifold from the 13B NA S4...will just delete the 5/6 port actuators and port match to the iron plates?
Can I bridge port the iron plates? Is it good even for Non turbo applications?

Thanks

 

1. for NA use, it doesn't really matter which set you use. however, i would say use the S4 set because if you ever want to build a turbo engine, the S5 engine is capable of doing more in stock form.

2. for the rotor housings, it doesn't matter so long as you keep them paired. they should not be mixed!

3. modifying the NA manifold with epoxy to fit the turbo block is fine.

4. there's no issue using the turbo blocks in NA setups. you can streetport or bridgeport them and make good power.

 

I ran that setup for a few years. It was a monster of an engine. First as a large street port, then as a half bridge.

I (I guess famously?) modded a 6 port intake manifold to match to it, and it worked really, really, REALLY well. It was probably my favorite engine.

 

Not sure if it was mentioned since I didn’t read through all the replies, but Pettit claims to have figured out how to modify 13B rotors to work with the Renesis side port arrangement. It’s mentioned on their Renesis engine build page. Seems like they only offer it as an engine build only and maybe not just the modified rotors or balanced assembly only, but that’s only an assumption based on their webpage as noted below. You would need to call and confirm.

https://pettitracing.com/pages/pettit-built-engines

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