Greetings! New guy trying a rotary swap into a Miata!
 

Hello everyone,

My name is Charles, I am currently trying to gather the parts, skills and knowledge to perform a 13B REW swap into an NA Miata. This will be a build focused mostly on Autocross and HPDE events.
The brand new REW block will be paired with an EFR7670 with the twin scroll T4 IWG housing. I am hoping this will offer me the perfect goldilocks zone for a virtually lag free turbo experience with a good, flat powerband. No high horsepower hunting for this build...
Ideally I would like to do the cleanest, most well thought out swap that I can accomplish. I could just throw it in there and make it work, but that won't make me happy. I am thinking that I can fit in a number of nice features, such as a Haltec ECU and PDM, an electric water pump, a V-mount setup, nicely done custom wiring harnesses, a surge tank, water/meth injection, solid dowel reinforcement with external oil mod, etc...
I plan on keeping the other stuff fairly simple; manual steering, no AC etc...

Any pointers and advice on this kind of swap is much appreciated, there are some areas that I am uncertain in and would appreciate as much wisdom as I can acquire:
-Mostly, how to position the powerplant appropriately in the subframe when making custom mounts, and ensuring proper alignment of the driveline and that there is no excessive stress on any particular point. I have noticed cracking of certain areas with bad placement, as well as rear bearing wear due to strain on the driveline and would like to avoid that as much as possible.
-Secondly, what kind of transmission and rear end to use for this swap. The stock NA8 transmission is not going to handle the HP of this build, and I doubt the stock diff will either. I could use an FD or T2 transmission, but I understand that some people are not fans of the gearing of the FD transmission, and that they reportedly have some trouble with shifts at high RPM. Any insight on firsthand experience with these problems, and solutions to them would be great, as well as any transmission alternatives to consider as well. I am not against something like a CD009 with a good adapter kit or even an H-Pattern dogbox, but both seem like they can end up costing a fortune in the end. Again, any ideas are welcome!

Glad to be here and I'm looking forward to gaining knowledge for everyone.

Welcome to the forum!!! That honestly sounds like an incredible build!!! I also have a Miata and mine is a roller I saved from the crusher. Its stripped to near nothingness so I have a blank canvas and have been considering a rotary engine in my car as well. When you create a build thread, consider me subscribed!

Thanks man! I have two options for cars it'll go into! I too have a totally stripped shell, as well as a running 1.8 Turbo I could use. Starting with a more complete car might be easier, and that one has a title so I can continue to road drive it. I'm the meantime I could work on the shell, maybe figuring out a bonded title or something for it in the meantime.

Good plan! I would love to see pictures of the car if you have any!

Welcome to forum

As far as your diff, I wouldn't bother upgrading unless you're planning on 400+lb/ft of torque. As long as you have an LSD (I recommend a clutch type over a torsen) you'll be fine. They're not very weak, my turbo miata sees ~320wtq almost daily.

Would be a cool swap make a build thread when you can