Is a 6 port motor originally a turbo motor? I get the feeling its not. How durable are the rotor housings from this engine, can they be used in a high HP FD motor.
Please let me know what series rx-7 they came from and the major differences between them and the Fd housings

Thanks

 

Go to banzai-racing.com and check out tech support section and see rotor housing identification. You will find what you need to know in details

 

If it is an s5 6 port you can use the housings once you swap out the exhaust sleeves. The 6 ports were NA motors, not turbo.

Some will tell you that the Series 6(13b-rew/FD) engines had better housings because the chrome material was of higher quality than the S5 engines. However, it is easier to find good condition S5 NA and TII housings without extreme spark plug cracking and usually they have less wear striations above the trailing spark plug hole as well. The s5 housings tend to edge wear a little sooner than the S6 housings but I tend to find the S5 housings have a smoother/less worn mating surface(on average) than the FD/S6 housings.

To answer your question, if the housings you are referring to have a hole on the outside of hte housing above the trailing spark plug hole to install a knock sensor, then yes they are interchangeable into a S6/FD engine. You will need to swap out the exhaust sleeves though.

Post pics of the housings you are considering and I will let you know if you can expect decent compression out of them or not.