I can never seem to find anything on this forum by searching. It must be me. Anyway, I saw this item which appears to make it possible to use a twin turbo from a third gen with a six port block.

cxracing.com: Lower Intake Manifold For Mazda 13B REW Rotary Engine 6 Port RX7 FD FC RX3

It's something I might try if there was anyone who I could turn to for help when (not if) I get hung up.

The six port has more intake area and I wouldn't have to worry about fabricating engine mounts. ON the other hand I would have to get lower compression rotors and everything from the lower intake manifold back to the air intake, intercooler and exhaust.

I have an 89 Vert, so more power would be welcome.

Has anyone done this?

Doug

 

You don't have to run lower compression rotors, no matter what you'll have to run a standalone ecu so you can tune it, or swap to a turbo ecu and "hope" for the best

 

Doug, I think the description is somewhat deceiving...

That lower intake manifold is for a 13b twin turbo engine (REW), and they are calling it 6 port, because its for a SEMI peripheral port configuration.

This lower intake manifold will NOT work on a any 13B NA 6 port engine.

You best best, is to find a 4 port 13B turbo engine from a 86-91 RX-7, is a direct swap (as far as mounting the engine to the car). My recommendation? Start with a stand alone ECU, you will be able to get a couple of HP out of your current setup, plus is the startup to a solid foundation when going turbo!

 

They are calling it six ports cause it has 6 intake ports/4 regular intake ports and 2 semi periferal ports.
4 plus 2 equals 6

 

Are we to accept this on just your say-so?
Show your work, please.

 

And more to the point even after it has been pointed out that this intake is for a semi-peripheral Cosmo RE, bolting on the REW turbos to a 6 port block is far from trivial.

The intake manifold is the smallest concern (and incidentally the REW intake can be modified to fit).

Engine management, fuel system, intercooler, exhaust, transmission, clutch, monitoring, about 7 and a half billion vacuum hoses to control the turbos, tuning...

 

not to mention the FC rear irons lack an oil drain port on the engine, then people tend to forget why it is that all the FD owners go to single turbos...maybe because the stock twins are unreliable and unrebuildable? making them cheap and easy to find because there is a reason why they are as such, then some FC owner gets ahold of one and a dim light bulb appears over their head...

why anyone would even want to spend $700 to make the stock twins work on an FC is beyond me, that's a good portion towards a good single turbo. with today's turbo technology a single turbo can perform nearly as well out of the hole as the twins did.