I was always told that for an exhaust to stand up to the heat of a rotary engine, that it ( for the most part ) HAD to be stainless to last long. I've heard people praise Racing Beat to no end; and after looking, their header is 1/8 inch Mild Steel.

What I'm wanting to know is; is it OK to use Mild Steel to make an exhaust for an RX-7? Will it last more than a few years? Thanks.

( I ask because there is a problem locally with welding stainless steel.... the few people who will do it for an exhaust charge a fortune )

 

Should be just fine!

 

Hehehe, yup. Stainless is a pain because you need to cut the parts flush and fit them properly. If you don't cut it flush, then you throw the piece in the extra parts bin and start again on another piece. Welding it isn't very easy either, and requires more skill and an upscale welder.

Mild steel is fine if you don't live in a winter environment.

 

the racing beat cat back exhaust is made from 304-stainless steel

and teh turboII complete exhaust system uses 409-stainless steel

 

The key to the RB system is the thickness of the tubing. For the most longevity, (As well as less exhaust noise in the car) I would try to use the same thickness tubing as RB. I used 1/8" mild steel on my system, and I've had it for 7 or 8 years now with no problems.

 

I have the RB y-pipe. Very heavy and sturdy. Mazdatrix catalog I have shows it black, but mine is chrome. In fact, I think it is so heavy that it lowers my center-of-gravity, offsets the weight of my sunroof way up high. A full RB exhaust should raise the skidpad numbers!

If only it was that easy.

 

My exhaust system is 100% thinwall mild steel and has been on the car for quite some time and it hasn't burned through yet.