IF you use thick enough material, even mild steel will work.  I used 321 for 2 reasons.  You can go thinner with it than 304 and reduce the weight.  I put 900+ hours on a set of headers made from .035 321 SS with no signs of deterioration (other than the metal turning a dark color).   321 SS is the nicest welding alloy I've ever worked with.  I tried welding Inconel with no luck at all so I would have needed professional help if I used that.

Tracy

On Tue, Oct 19, 2010 at 8:22 PM, Jeff Luckey <JLuckey@pacbell.net> wrote:

I thought that people were commonly using 321 for Rotary exhaust systems
because it has a higher temp rating.

It's been a while, but I vaguely remember looking it up, and the max working
temps were something like this:

304 = 1200F
321 = 1600F

So, my question is, are people using 304 successfully for Rotary exhaust
systems.  If so, that's great, because it's cheaper & more readily
available.



-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Ernest Christley
Sent: Tuesday, October 19, 2010 07:51
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: header parts source

Jeff Luckey wrote:
> Does Columbia now carry 321 stainless.  IIRC, I pinged them about a year
> ago and they did not carry 321 stainless…
>
>

I also bought bends from Columbia.  Their service and delivery was
excellent.

I don't see any mention of 321, but I wasn't really concerned about it.
Given the diameter of tube we have to use for
exhaust flow, and the thickness we need to contain the exhaust pulse, and
the corrosion resistance characteristics of
the alloys at elevated temperatures, I couldn't see enough of a difference
to stress over.

>
> ------------------------------------------------------------------------
>
> *From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
> *On Behalf Of *kevin lane
> *Sent:* Monday, October 18, 2010 22:03
> *To:* Rotary motors in aircraft
> *Subject:* [FlyRotary] header parts source
>
>
>
> I have been happy with Columbia mandrel bending.  they make their own
> parts, family run, and significantly cheaper than burns.
> http://www.mandrel-bends.com/catalog/
>
> last week I finally got the v-band, another 90°, a flex joint, and
> muffler added to this header.
>
>
>
>
>
> KevinLane Carpentry
> www.KevinLaneCarpentry.com <http://www.KevinLaneCarpentry.com>
>



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