Not sure if anyone has attempted to have done a custom 20B w 13B N/A parts. With the 6 Port Injection that works on the GSL-SE, S4 N/A and S5 engines. Good for low end torque and great on high end power, except on a 20B. 6 Ports open below 4500 Rpm'ish (as an example) and all 8 Ports open after. If it has been thought of or attempted, is there any gains to doing it over making a 20B Cosmo N/A?

 

4 port rotaries make more power than 6 port rotaries when in modified Naturally Aspirated form- so, its a futile exercise.

6 port was a way for Mazda to make good power from NA engines (through late intake closing) with all the constraints of emissions.

Its like Honda Vtec.
Good for a car that has to pass emissions, but a Honda race car will often eliminate the complexity/valve train mass and use a bigger cam/higher RPM w/out Vtec (vtec killer cam).

However, adding a semi peripheral port to 4 port rotary (or 20B) or eliminating side ports and going full peripheral port is a proven way to gain NA power in a rotary.

If want to see what I mean, search 13B NA dyno sheets.

You will probably find more NA 4 port 13Bs over 200rwhp than 6 port 13Bs even though the vast majority of NA 13Bs are 6port.

Of course many will be bridgeport because thats the easy way to make 250rwhp NA13B.

So, there is the bridge port option for 20B too; but semi p-port better cause your not hacking up precious 20B side plates to make it and it can make the same power.

 

well, assuming you are planning to run the side ports, there would also be the issue of the center rotor not matching the front and rear, too. however, if you plan to go peripheral, then why not?

 

the 3rd rotor adds more low end than the 6 ports would....