hi
going to rebuild 20b using new housings.
are rotor housings from FC,FD and 20B compatible?
i will make porting anyway so stock port size is not important. how about other propierties like streigh, cooling passages etc, are they same?

also how about end plates and intermediate housings, may i take it from FC 13B?

FC ones are cheaper, this is why I am asking...

thanks

 

20b End plates are different than FC and FD. You *might* be able to get away with using 13B-RE irons, but Im not sure. Also, FD and FC rotor housings are compatible, however, you will need to mill out some of the tension bolt holes because the 20b uses a few tension bolts that are thicker than 13B.


neil

 

Only the rotor housings are interchangeable, none of the irons are.

You do not need to mill out the tension bolt holes at least for FD rotor housings, don't know about FC's.

 

Stick with the 20b irons. I believe there is more material around the dowel pin holes to help keep the block from cracking.

 

fc and fd housings are different. the leading plug holes in the fd are lower i do believe, also i'm not sure if it's the front or rear but one of the fc housings has a port into the coolant passage, i think it's for turbo coolant feed, the fd does not have this.

 

are you sure? I have two brand new FD rotor housings and none of the big tension bolts would go through the holes on either one.

 

FC and FD housings are compatible.

What determines where the leading plug hole is is te batch. Some FC housings arent compatible with other ones. Yet might be compatible with some FD housings.

I had a few housings here. And realized that the plugs wouldnt line up. Then found out that depending on the build date mazda would change some minimal things.


So if you did want to use other housings try to get 3 of the same time/batch if you can.

 

that's good to know, i thought all fc housings had the same plug location.

 

Yes I can speak from personal experience. Did you go with fronts or rear rotor housings? They are different as far as the emissions goes; I went with fronts (if I remember correctly) that did not have the emissions ports. I did get mine fresh from Japan this spring as well and had to wait a couple months for them to change tooling out as they were only running RX-8 rotor housings before running FD's and then 20B rotor housings around June/July time-frame which were last on the priority list.

Having worked at a foundry I can tell you that there can be a lot of slop in tolerances so your heat run may be different from the ones I got because of core shift, CNC jig shift, etc.