I'm in the midst of rebuilding a Cosmo 13B RE (2-rotor) and I thought I'd post info and pictures as I go through the process. It's going into a 95 RX7. My original intentions were to just install this engine in "as is" condition. I was worried that the engine wouldn't be 100% healthy and the thought of tearing the motor back out to rebuild it didn't appeal to me. So I ripped her open. Turns out she was just fine. Really really good actually. Oh well.



I'm waiting for a few items to arrive (rebuild kit) so I'll post images of the internals, specifically the intake and exhaust ports. Here's the exhaust port as seen from the inside of the housing.

Here's the exhaust from the turbo side. The sleeves are very restrictive. If you've ever wondered why a three rotor is so quiet, this is why. The simple solution is to pull the exhaust sleeve pins and replace the Cosmo sleeves with FC or FD sleeves. Don't forget to port them!

here's the primary intake inlet. About the same size as an FD port. There's room to hog these puppies out, but I'm not planning on anything too crazy. Check out the machining/casting mismatch....that can't help power too much!

Here's the primary inlets, intake manifold side. Again, there's plenty of casting to be removed to clean them up.

Here's the secondaries. Much larger than the FD's. I had a chance to lay a porting template over the top of the Cosmo ports and the template (monster street port) wasn't too much bigger...sort of scary. I plan on going as far as I can with the secondaries.

Secondary, from the intake manifold side. You can almost hear your own echo https://www.nopistons.com/forums/pub...#>/BURNOUT.gif

And here's what I did today while I wait for my rebuild kit, porting kit, etc....I started at about 9 this morning and finished about 5:30 this evening. Polished the UIM, throttle body, and repolished my GReddy elbow and Cusco strut tower bar. Forgot to polish the IC piping! Once the engine is removed, I'll polish the LIM, front cover and anything else I have time to polish. I'm almost finished polishing the housings as well. I'll have pics soon!

Cool,whats involved in putting the 13B RE in place of the 13b REW?

Pretty much nothing...apparently, even though the Cosmo motor mounts bolt on in a different location, the rear housing has all the bolts for the FD's engine mounts. Everything else is identical. Has the same primary injector bung, etc...some things that need to be swapped out are the stationary gears (trying to figure out which one), front cover (FD's bolts right on) and the FD's intake manifold system. You can use the Cosmo's intake manifold, and if you have the time/resources, I definitely would do that. You'll need to make a 1" spacer to fit between the throttle body and the GReddy elbow so everything lines up. The Cosmo secondaries are top feed. You could mod the stock fuel rail and run 1600's. I already had 1300's and didn't want the extra expense and setup time.

The cosmo intake has much bigger runners. here's a look at the mouth of the intake. That U slot on the bottom is exposed when using the FD's throttle body. One could simply weld it shut but a spacer would be better as it'll allow everything else to line up. I'd do it out of phenolic material. Cheap, easy to cut and shape.