I’ve been working on an na 13b engine from a 1990 FC. I’m 99% sure the coolant seals are blown and I know I would need to replace the housings that are damaged, but I was wondering if I will have to strictly only use parts from s5 engines or if i’m able to use parts from different rotary engines, for example using s4 housings. If I am able to do this, which parts can I use in my 13b?

 

welcome to the board.

well, things will physically bolt up between the two series - rotor housings, side housings, manifolds, etc. however, there are some differences between the two, some major, some minor.

EGR is a difference. i consider this to be minor, but you may look at it differently. the rotor housings, on the other are different and that is a major one ... the spark plug holes are in different places, so if you choose to use S4 housings, then you will NEED to use a pair, not just one.

overall, it's probably in your best interest to keep everything S5, but ultimately, it will come down to what exactly you are changing.

hope that helps.

 

When rebuilding your 1990 FC RX-7's 13B engine with blown coolant seals, you can likely use Series 4 (S4) housings in place of Series 5 (S5) ones, as they are generally interchangeable. However, ensure compatibility by checking for any design differences that could affect performance. It's crucial to use coolant seals appropriate for the series of housing you choose to ensure a successful rebuild.