new to rotary engines I am embarking on a steep learning curve. After looking around here I am seeing people parting out far nicer cars than mine but I refuse to give up. now that mine is finally running I am looking to replace the high quality flex pipe exhaust with a header system. I think I understand the basic concepts of exhaust theory at least on piston engines but could sure use some tech help here. Unfortunatly I have far more fabrication ability than money so I am considering starting with a 16212 header kit into a 2 into 1 collector (I don't see any mention of rotories and scavenging). From the collector back to a single muffler out the back or maybe even the side. Guess my first question is if that makes sence? what do I need to know about the variable ports? are the primary tubes in the kit appropriate or should I start with a flange and build from scratch (I know that bigger is not better because loss of velocity will kill scavenging). what is an appropriate primary length? Am I forgetting anything?

 

I don't know what a 16212 header is, but rotary exhaust theory is well known so there is no sense putting much thought into it.

Your primary goal is going to be to keep noise down, unless you really do want a car that requires the use of ear plugs.

The best NA rotary exhaust is a set of 2 1/8" pipes that merge at the rear bumper into an 18" megaphone. In most stock and mild port applications, that is how you will make the most power. Of course, you will deafen everyone within a square mile.

So start with a quality header like the Racing Beat header. Then 2.5" piping back to two resonators and two quality mufflers. Single exhausts are generally loud (and in my opinion, look stupid) because a single muffler cannot keep the noise down while maintaining flow. This is the reason Mazda went with two.

You'll now need to actuate the aux intake ports, so check the FAQ for details on how to do that using the air pump.