Paul Yaw wrote:

Paul wrote:

Marvin Kaye wrote:

The discussion always seems to jump straight to Inconel for exhaust
manifold construction but there's never any discussion of stainless.  Seems
to me that 321 stainless (which is much cheaper than Inconel) and routinely
used on aircraft exhaust systems should be adequate to the task, even for a
turbo manifold.  It's what's used on the twin-turbo Continental TSIO-550.
Thoughts and comments?

   <Marv>

The EGT is higher on a rotary Marv. Thick wall SS might work however.

Paul Lamar

I don't have any scientific theories to back this up, but I believe that
321 is sufficient.  I seems to last forever on road race cars.  This is
even true of PP engines with egt's nearing 1900 F.  While we are on the
subject, the exhaust port sleeve in the early rotaries was made from
stainless.  The later turbo models had a sleeve made from something
resembling cast iron.  For all I know, it may actually be cast iron.  It
will stick to a magnet, and you can easily crack it.  Maybe Mazda was
trying to save money.  Anyway, if you intend to build a turbocharged
rotary, remove those sleeves and replace them with stainless or
inconel.  If you dont, they may end up in your turbine.

PY

I think we need to differentiate between normally aspirated and
turbo charged. Stainless seems to work fine for a normally
aspirated engine as proved by Tracy. I would not trust it
for a turbo engine. An inflight fire from a cracked manifold
could ruin your whole day. With things like this I tend to 
take a very conservative approach. As Tracy Saylor told me;
"cheap and aviation are mutually exclusive".

My interest in the rotary is not simply one of cost. I think
it makes a better aircraft engine.

Paul Lamar
 
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