How to bild 4 rotor rx7
 

Hello everybody, its me again
I have seen such posts like 4rotor rx7 fd and i wanted to know : how do you build 2 extra rotors in an engine

Do you need to make extra space with drilling in the rotor bay or what do you have to do there


Or can you build a 3rotor rx7 to

Do a search on YouTube for 4 rotor RX-7

It is all custom, and requires major fabrication work to happen. It’s not something you can slap together. 3 rotor can be had by grabbing a Cosmo engine, but it still will require mods to the car to fit. It’s not a drop in deal.

You’d better have a lot of tools and ability or a lot of money if you want to do stuff like this.

welcome to the board. :)

it's not a simple affair, by any means. the following is not all-inclusive, but it should give you an idea of what goes into it.

1. you will need the eccentric shaft. they are available, but very expensive.
2. you will need two intermediate housings fitted with stationary gears and oiling provisions.
3. you will need tension bolts/studs for the application
4. you will need an oiling system, probably dry sump (i don't know if the stock 13B pump can supply adequate flow for basically 2 engines)
5. most are peripheral port, so you will probably need that. i've only ever seen one 4 rotor build for using the side housing intakes and i'm not sure if it ever ran. so that will be a huge deal.
6. custom ignition, and exhaust are a given, though i think the 4 rotor engines are easier because they can basically use the 13B phasing, where as 3 rotor engines are phased different.

for your last question, the answer is yes. Mazda built both the 20B and 13G engines. 20B was a production engine, so that's the easiest route. however, you can build your own custom 3 rotor, i'm not sure how that differs from a 20B mechanically outside of the fact that there is no "thick" housing, so you would have to go peripheral or settle for uneven flow with the side housings.