ok, i'm going to buy the flange from racing beat, but i need to know whats the best exhaust pipe to use to make this manifold for it wont crack

Stainless steel, 5mm wall and good welds

is that the only material that can be used?? and will that be able to be welded to the steel flange.

Right on, you can also you mild steel..

Mild steel is not good to use due to the corrosion properties..

SS expands and contracts more more than mild steel so that has to be considered in the design process, although its not that big of a deal on rotaries cause there is only two exh ports and the manifold is fairly small.

Stainless wont crack as long as you use thick enuogh material and dont under-cut the welds too bad

321 stainless has better heat strength than 304. Inconel is the pimp daddy of manifold materials.$$$$



Burns Stainless

According to the site it is a little more difficult (different) to weld so probably wouldnt be a good idea unless you have some experience welding...mabey I'll get some and try it out https://www.nopistons.com/forums/pub..._DIR#>/dry.png

Schedule 40 , steel pipe and elbows . works great , is cheap and easy to weld . Myself and many have been using this down here without any problems (corrosion and other wise).

Inconel gives you HUGE puddles around the welds

Metal steam piping always does the trick to.