<< > > > > > I tried the Edelbrock RPM series on my plane. It lasted about
20 hours
> > > > > before self destructing. Packing (ceramic) blew out in about 5
hours. I
> > > > > sent pictures of it to the list some time ago.
> > > > > Tracy Crook
> > > How about Inconel-718 turnings off a lathe? They are a bit stiff and
can cut skin
> > > to the bone instantly but if packed into a casing should work.
> > >
> > > Blake
> Blake,
> I assume that you mean that the Inconel-718 would be used for muffler
packing. What about the rest of the muffler. Tracy stated that the RPM
series muffler self destructing in 20 hours.
>
> Wouldn't it be best to just make the entire muffler from Inconel? I know
that this stuff is ridiculously expensive but I don't want my muffler
self-destructing into my pusher prop. Every time I consider using 316-SS
instead of Inconel, I remember all the stories about Tracy's mufflers being
destroyed after relatively low hours. My problem so far has been finding a
supplier for Inconel tubing and sheet that is willing to sell in the small
quantities we need for building our mufflers. I've been looking for nine
months without any real success. Most suppliers that are willing to sell to
individuals want to sell full sheets and uncut lengths. The last I figured,
I would have to buy about $2000 worth of Inconel and would only use about one
forth of it for my system. Is there anyone else out there who wants to build
their exhaust system from 600-Inconel ??? If so, this is a product that
would definitely be best to buy in a quantity group purchase. If anyone
knows of a good supplier and / or would be interested in participating in a
group purchase........let me know!!!
> Thanks,
> Don Mitchell
> Plano, Texas
> Standard Fixed Gear Velocity (~70%)
> Mazda 20B with T. Crook EFI / EI / Redrive
> N 6 V V (Reserved)
Don, not to worry.
Just go up a bit on the muffler wall thickness made from stainless steel.
Ed Anderson's SS pipes are quite thick and they don't even discolor.
They show signs of lasting forever. As I recall they are .065 thick.
I forgot for sure Ed. How thick are they?
Tracy's original .035 thick SS muffler under the cowl lasted
600 hours. Tracy's original muffler is on the left and what was
left of his Eldebrock muffler on the right.
I would guess that a .050 thick SS muffler should last ten years.
Paul Lamar
I have more than two sets of Inconel Indy car headers. I came by them cheap
because they are discarded as a cycle replacement item. So each team has many
sets to get rid of each year. They are made from thin sheet stock rolled into
short pieces of tubing. Tight turns are pressformed and welded up by hand.
The flanges are cast. Every tube is a hand formed work of art. I bought them
from the man who used to make them for the Rahal team. He said that they are
so thin they are likely to crack if stressed at all while hot. They are used
three heat cycles and discarded. They are now manufactured in England for
about $10,000.00 per set. You can TIG them with stainless filler rod.
I don't see a big weight savings for Inconel in rotary mufflers. The
pounding almost requires a cylindrical shape in order to stand up for very
long. The material thickness would have to be close to that of stainless
steel to avoid cracking.
The square muffler soon to be tested is the wrong shape for a long lasting
installation. If it in fact it is good at muffling, a new design using the
same system, but with a cylindrical case should be built. Since there is
little room, there is no way of protecting it form heat and the powerful
pulses.
Lynn E. Hanover
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