I'm building an NA 13b to swap into my FB. I planned on building a full S5 NA engine but things have gotten more complicated. I bought a large batch of S4 and S5 parts for $500 but not enough to build a complete engine of either. Here's what I have:

Series 5 NA:
E-shaft
Rotors (2)
Rear & center iron (front iron is junk - step wear. center iron has 0.003" step wear)
Front housing in great shape (rear housing damaged)

Series 4 NA:
All 3 irons in good shape
Both housings in kind of bad shape

I'm looking at two options right now but please tell me if either won't work or if there are better options. This is my first time building a rotary so it's new to me.

1) Find a used S5 NA rear housing (or any housing? I have a RB header so no EGR). Use the S4 front iron and S5 NA parts for everything else. Finding a good S5 housing
much cheaper than a new one has been hard.

2) Find a set of used S6 (FD) housings (not much more than the cost of a SINGLE used S5 housing), swap the exhaust sleeve from my S5 housings, then build a block with S6 housings, S5 NA e-shaft and rotors, and S4 NA irons S5 NA center and rear irons with an S4 NA front iron.

Any advice?

 

If you get S6 housings don't swap the exhaust sleeves. You're better off without the diffusers flow wise. They say there is a noise increase without them. My build took long enough I didn't notice. Also if you think you might want to port your exhaust you need to get rid of them anyway. Also don't mix & match s4 & s5 rotor housing as IIRC the spark plugs are in slightly different locations. I think I'd use the S5 center iron to get rid of the egr valve. Also even though you didn't ask about it would street port it while it's apart.

 

Thanks, the EGR issue slipped my mind so regardless I’d want to use S5 irons. I don’t plan on porting. Too much I could screw up and the rebuild seems hard enough already

 

the simplest route i see is to use the S4 front and rear that you have and use the S5 intermediate. done.

if you can find S6 rotor housings, then by all means, get them and use them. otherwise, just get one to match the usable S5 one you already have. again, done.

 

I can’t find s5 or s6 housings so far. I’ve only been looking for s5 but now that I realize s6 will work I’m expanding my search. Everyone either wants nearly-new prices or the housing are rough

 

Yeah, you're preaching to the choir with that one. I'm always looking for housings. I see you're in TN. Have you been in contact with Rotary Resurrection?

 

Yeah... that's what everyone says, contact Rotary Resurrection. I did a while back. He'd want $400+ for one in similar condition to my current S5 housing, and I'm not going to spend that when brand new ones are $600. He's also been a bit of a jerk to communicate with so I'd rather not bother. He was actually upset with me for sending him a facebook message and not tagging him in a comment instead....