Jerry Hey wrote:
Paul, in the attached drawing, it is clear that if I
stick
with
straight line joinery with miters, exhaust sections
running
at
angles
will lose capacity. I believe the solution is to use
curves
instead
of
corners. Unfortunately, in my hands, drawing a curved
line
in
cad
is
more difficult that cutting one out of stainless steel.
Could
you
model the pipe shape for me and send as an Iges file.
Also
at
the
top,
near the muffler, I will need to put in a slip
connection,
so
the
need
there is need for a short straight section. The
exhaust
pipe
in
question leaves the muffler at 45 degrees and continues
for
10
inches
and then in turn down for 10 more inches. The section is
4 x
1.75
inches. This is a real system that I will be building.
Thanks,
Jerry
Jerry Hey
j-winddesigns@thegrid.net
Is this a side view Jerry? If it were a front view the
top
part
would
be
round.
Paul Lamar
Yes, side view. I want to have a curved version that
follows the
same
path roughly as the mitered version. I want to keep the
4
x
1.75
section constant through out. No round parts. If
this
is a
lot
of
trouble, don't bother. I can lay it out in pencil.. I
just
don't
know
how to get the computer to do it. Jerry
Something like this? The side view looks distorted but
trust
me...
it
is
indeed constant area.
Paul Lamar
Here is a version curved in both front view AND side view
along
with
the flats.
If you have not figured it out yet Rhino is amazing :) I
could
never
in a million
years draw this with a pencil. :)
Paul Lamar
Can you place the flat side view on a grid so that I can pick
up
the
full scale pattern? Thanks, Jerry
Sure or you can print that and scale it up so the width
equals 4
inches.
Or I can send an IGES.
Paul Lamar
Here they are on a one inch grid.
Paul Lamar
Thanks again, we have decided to have the 4" exhaust pipe angle
back
from the muffler at 45 degrees for 10 inches and then curve down
to
vertical for another 10 inches. If you can draw that on the one
inch
grid, I will try to find the graph paper. Jerry
Jerry, Thats what the double curve one does only it also does an
S
curve
when looking at it from the front. You already have the flats on
grid paper
but here they are again. This is for the Tailwind as you did not
tell me it
was for the BD4. I'll have to check the fit on the BD4.
BTW Bob white, why the evap cores?
Paul Lamar
Opss I sent you the ones with the out the grid. Here is the grid
again.
If this is for the BD4 it will have to be redone anyway.
Paul Lamar
Why not one straight piece guys. A lot less work. You might find
some
stock .049 SS tubing.
Does not have to be 321. 304 or some other SS would work here. Make
your life simple.
If not rectangular get round and squish it between metal plates in
a
hyd
press to oval. I can give you a flat cutout pattern where the tube
intersects
the six inch round can.
http://www.tubemethods.com/
Paul Lamar
It the drawing, you had to move the exhaust pipe outboard on
muffler
which I don't want to do at least not until we have had a chance to
gain more practical experience. I want the exhaust gases to hang
around a bit losing speed and temp. The further outboard the pipe,
the
sooner the gases will exit. Of course, this is just a wild ass
guess
on my part. Who knows? Also, the pipe seems to be growing in
size.
The 4 x 1.75 inch is more than adequate. Lastly, I really like
the
trick appearance and moldability of the rectangular exhaust pipe.
But
of course, if your are just running the straight pipe down at 45
degrees, a crushed round pipe could be used. You need a three inch
round pipe and you can't crush it very much without making it too
small. Jerry
Jerry Hey
j-winddesigns@thegrid.net
I don't think anything else will clear Jerry. I also think it will be
hard
to measure a difference in noise. They are all 1.75" by 4 inches.
If you scale them you will see it is an optical illusion.
It is up to you. I can probably design a spaghetti down pipe that you
can't
or won't build build :) How about a rectangular down pipe with a 90
degree twist?
Start with a 5 inch round pipe and when you crush it it will come out
to roughly the right area. Of course it is hard to find 5 inch .049
thick.
Maybe .063 but I doubt it.
BTW a 4 inch by 1.75 .063 thick pipe 20" long will weigh 4.3 pounds.
.049 thick would weigh 3.3 pounds.
Paul Lamar
One pound only! I rest my case. Jerry
Did I make a mistake? Lets see a 4" inch by 1.75" rectangular tube un
rolled is
11.5 inches wide. By 20 inches long is 230 square inches. By .063
thick is 14.49 cubic inches. Since steel is .3 pounds per cubic inch
then that is 4.347 pounds. Where did you get one pound?
Paul Lamar
The difference between .063 and .049. Jerry
Oh OK A pound saved is a pound earned :)
Paul Lamar
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