Stainless and the Racer
While the corrosion resistance and elevated temperature properties of the various stainless steels make them popular in the aerospace, food handling and chemical industries, we racers really don’t have much use for them.
For almost all of our applications, either steel or nonferrous alloys do the job as well if not better – and at a lower cost. The only stainless that I ever use is austenitic type 321, an alloy originally developed to stop the cracking of piston-engine aircraft exhaust systems. It makes truly outstanding race car exhaust systems, if the money is available. In my present case – ever since I made my decision not to work full time for the big teams – the money is usually not available and I use 1020 DOM. The stainless is lighter and more fatigue resistant, but except for turbocharged engines and long-distance racing (neither of which I do anymore, at least for now), the stainless is simply not cost effective. It does not sand bendable, so the exhaust system must be fabricated and welded from a section of mandrel bends and straight lengths.
The bends are expensive because the material itself is expensive; there are no bends in stock anywhere; none of the tube benders want to know about it; and when you do find someone willing to bend it, you pay a giant setup charge. If you decide to make a stainless system (or to have one made) remember that, regardless of what the man who agrees to do the job may say, 321 is the ONLY stainless alloy suitable for the job. "
- Carroll Smith's Engineer to Win, 1984.