Hi Paul
"I was wondering if anyone while they have been traversing the vast space of the
internet has found a source for 309 stainless steel tube."
I first question if you really need 309?? I know Rotax is now using 309 on new
style exhaust, they used to use something else. Is your exhaust 309?? Old style
is said would be lucky to last one TBO, 309 is expected to last at least a few
---From what I understand.
Anyway if you are just wanting to make a new exhaust pipe I think 304 should be
fine. You can weld 304 to 309 with 308L welding rod, www.mcmaster has both.
If you want better heat resistance they sell 316 tubing in 1.5", I am pretty
certain
you could weld 316 to 309 with 316 rod they sell, but not certain 100% on
that so check , McMaster sell both.
321 stainless is used in aeroplane exhausts, better for temp than 304, I didn't
check if McMaster sells, but Spruce sells, not sure if you can weld 321 to 309
and what rod if you can but if you just need it for pipe which would be overkill
but better for temp than 304.
I have looked for 309, not too successful, however McMaster sells a 1.5" 3' long
rod, you could knock yourself out and bore it out, probably would need to cut
it down to bite sized pieces and weld it back together after you made a pile
of chips.
You may want to consult with an aviation muffler/exhaust specialist. Have a look
in Trade a plane, think Dawley is one that has a good reputation.
I am installing a mixture control on my 914, to monitor how I am doing. I will
be welding a 304 stainless bung to my 309 muffler using 308L rod. The bung will
hold a O2 sensor and drive a mixture monitor which I will use in addition to
two EGTs. I researched in past and 308L is a good choice for welding 304 to
309.
Off topic a bit but will stand on my soapbox and mention more ethanol is needed
compared to gasoline to achieve proper mixture. Thus E10 will run leaner than
gasoline with no alcohol with same tuned type 64 Bing carb. Especial on a 914
that you modified the intake track (inter-cooler is just such a modification)
when you are making some BTUs you want to be sure you are rich enough. Rotax
wants you to measure carbon monoxide on each cylinder when making war emergency
power (115%). They issued a bulletin a while ago that is still in effect to
make sure you are not lean. I will throw a dart and say they will probably bring
this up again in a service bulletin when using E10 in the future. I like Bing
type 64 carbs, if anything I want to run a tad bit rich when making some BTUs,
and OK to lean when you are not.
Off soapbox.
Good luck
Ron Parigoris
BTW if you are mutilating your exhaust and want to fool with a mixture monitor,
I am using Split Second ARM-1
http://www.splitsec.com/
Nice small unit driven by a O2 sensor. Since you are not driving a computer that
is using info to adjust mixture, even with 100LL use sender will begin to slow
down and yet still be fine for monitor. Dart throw is 100 to 200 hours with
100% 100LL. There is a routine upon start up that will tell you when it is time
to replace sender
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