Classic exhaust ?

[RR Fan Dan]

Without going through another post. Between the 409 stainless and aluminized steel pipe which is better? Going to order a new exhaust this spring. Car is all original.

304 Stainless

The difference between the types of stainless steel is the amount of chromium and nickel found in each. 304 stainless steel contains a much higher percentage of chromium and nickel. This makes it much more resistant to rust. 409 stainless steel is still more rust-resistant than aluminized steel.

​

​	409 Stainless Steel​	304 Stainless Steel​
Chromium​	10.5% - 11.75%​	18% - 20%​
Nickel​	0.5%​	8% - 10%​

How can you tell the difference?​

409 stainless steel can be almost 90% iron. This means a magnet will stick to it. It will also develop surface rust over time, especially after being exposed to heat.

304 stainless steel has a much lower concentration of iron. A magnet will not stick to it. It will also develop a golden color over time, after being exposed to heat.

**Welded or bent areas of 304 stainless steel could be magnetic. If you do check it with a magnet, check a straight section that has not been welded.**


As a side note, having been in the nuclear industry for 40 years, I can tell you there is a reason that 304 stainless is the only steel used in reactor components that come in contact with reactor coolant.​

 

[mountain33]

Since Im in my mid 60s then 409 it is. I figure somewhere around 10 years is good enough. Remember TMI I worked for the parent company when all that went down. GPU

 

[A4GTX]

Don't know what to say. I didn't look too close but I asked him and he said no Chrysler markings.

Well, I have a dual exhaust setup ordered for a ‘67 Monaco 500 that I’m working on, so I guess I’ll find out.

 

[Some Car Guy]

I’ve seen aluminumized pipe last for decades and not be looking shabby. I did a low deck to Rb swap in a 70 challenger. Car had old rusted looking pipes and the one header didn’t let the pipe clear the crossmember at all after the swap, hit going over bumps with the B block. Shop welded in a section of aluminized and it was perfect about 5 years later when I did an entire new exhaust. For instance. I’ve seen plenty others that looked good for longer on cars that get driven seasonally.

I went with ss resonators in the GTX last year because those can let water settled, but I’d have a hard time spending the money on a full ss system unless it’s a hemi type show car.