i just bought myself an rx3 coupe and the guy who sold it to me gave me a ton of motors some lil 12a's a t2 one and a few 13b's n alota the 13b six ports. ive never seen a six port b4 or knew they existed. are good motors? it seems to have rather long duration and a pretty generous size port for stock. i did research n found that all 6 ports in japan came turbo. n all 6 ports state side were NA. why do you think that is? and does any one know if its safe to run it with out that rotating valve?

 

Rotating Valve????

All JSPEC's where 4 Port Turbos, Not 6 Ports, this was because of emission issues

 

After just taking 1 apart. it looks like the rotating valve controls air flow for the upper intake port on the 6 ports. I assume its for 100% throttle or more so "secondaries". It turns n blocks the air flow. I don't have any manifolds for it but I hear t2 ones work. But I don't know if its safe to toataly remove it.
If those motors are any good I plan on boosting it with mazda trix ports and t2 rotor housings. If I can figure out how to post pics on here I can show ya what that valve is

 

u can remove the vallve if you want but it isnt any fun because it kills low end power.

 

I believe all the non turbo engines after 85 were all 6 port. The ports open with exhaust back pressure on S4 models and with the air pump on S5 models. They change port tuning so you have better low end torque and better high speed power. As the post above says, you can remove them but will loose some low end torque, your high rpm power should stay the same.

 

Throw a 6port renesis in the RX3 coupe. That would be really cool. You could buy a crashed rx8 from an auction for 3k to 4k, maybe less. But youll have the ECU, wiring harness, the engine and the returnless fuel sytem.