Adam's Canadian 13B Rotary 818-SR Build

[Canadian818]

C818 For what it is worth, I bought a 1983 RX7 with a bad 12A. I had access to a Mazda factory built marine 13B with a four barrel carb that dynoed at 200hp. I reconfigured for the car and bought Racing Beat exhaust.
The primaries had pre-chambers and twin pipes continued back to the rear muffler which was kind of a Borla copy. The sound was what I described as "titanium bees". It was terrific and not too loud.
jim
RX-7 redux 002.jpg
RX7 engine.JPG

I love a clean FB, very nice car! With some good resonators a rotary can sound good and not crazy loud. My problem is I don’t have the room for long resonators or pre-chambers like on a rx7. The car also got quite a bit louder after the rebuild as I went aggressive with the engine porting. I’m about halfway done the new exhaust now. I’m using a much bigger muffler that’s 1 into 2 and then two resonators but I’ve eliminated the cat. It should flow better than before and with any luck be quieter too. It’s using up all the real estate above and on the sides of the trans and adding weight, so hopefully it’s not for nothing.

[J R Jones]

I love a clean FB, very nice car! With some good resonators a rotary can sound good and not crazy loud. My problem is I don’t have the room for long resonators or pre-chambers like on a rx7. The car also got quite a bit louder after the rebuild as I went aggressive with the engine porting. I’m about halfway done the new exhaust now. I’m using a much bigger muffler that’s 1 into 2 and then two resonators but I’ve eliminated the cat. It should flow better than before and with any luck be quieter too. It’s using up all the real estate above and on the sides of the trans and adding weight, so hopefully it’s not for nothing.

C818,
My Nikki four barrel was small, the Racing Beat Holley would have made more power.
I had bridge ported secondaries and stock primaries that resulted in great idle and throttle response. Getting vacuum and velocity across the venturis is a challenge.
As mentioned on the forum before, the SCCA GT3 RX7s use a large muffler can with lava rocks inside. When they disintegrate they open the can and put in new rocks.
The sound level was legal on the track, I don't know about the street.
jim