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Hi Rusty,
I presume you want them
pre-bent? If not you must anneal? the tubing to "O" (soft) condition prior
to bending. Otherwise, you will surely end up with cracks. Then you
can have the heat treated back to the 6061 T3/6 condition.
If you order from Burns and bent
tubing, you will get it in the "O" condition or a slightly harder condition due
to the cold work hardening from bending. I found that heating them at 500F
for 8 hours seems to harden them a bit - they don't ding as easily as the "O"
condition.
For intake runners, I generally use 1 3/8" OD 0.058
or .065 wall thickness for the primary. I use 1 5/8" OD same wall
thickness for secondaries. I have used from 1 1/4" to 1 3/4" but I
think the other diameters are about optimum. Its all 6061 from
Burns. You can use 6063 (architecture aluminm alloy - a bit more corrosion
resistant - but hard to find in bends.
You can get the Burn's lengths and then added to
the lenght. You can do it by adding a short length (2"?) of the next
larger diameter size as a coupler so that both ends fit inside. However,
its difficult to find a welder that can weld thin tubing. I have had good
success with brazing the thin wall stuff.
There are a couple of other places for bent
tubing, but their "tangents" as they call the length before and after the
bend are even shorter and the walls much thicker - almost like
pipes.
You can get pipe bends (Elbows) from
RBWagner schedule 40 which has walls of approx 0.12 ". It is much heavier
but you can use it just for the bend and then stick in straight light weight
tubes from most of your runner lenght.
Just a few options. Me, I am currently making
the mold for another plastic intake part. This time it will be for the
lower part of the intake, so I can use inexpensive straight tubing with the bend
in the plastic casting rather than keep paying for expensive pre-bent
tubing.
Good Luck
Ed Anderon
----- Original Message -----
Sent: Friday, September 26, 2003 1:35
PM
Subject: [FlyRotary] aluminum intake
tubing?
Ed (or anyone else),
Where's the best place to
get aluminum tubing for intake runners. What alloy, and wall thickness
is most common? Burns has 6061 with a 90 degree bend, but the legs
are only 4" and 12" long, which won't be quite long enough. Has
anyone had good luck bending this size tubing yourself?
Thanks,
Rusty
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