"I want to make the runners that go from the intake plenum to
the throttle body. This requires a 180 degree sweep. Can
anyone tell me how to approach such a project. Or
recommend a good book on the subject."

"Jerry Hey"

"The idea is to create a tool that "disappears" inside a
locked shape. We use various types of mandrels but the most
common technique is to make a water soluble mandrel. There
really is no limit to the shapes."

"Here is a good source for the water soluble plaster."

http://www.acrtucson.com/

"Aquacore is about $100/5gal bucket as I recall.
I think it's corn starch w/plaster... shhhhh"
"Marinus B. (Ben) Bosma"


According to Ben Aquacore is plaster and
corn starch so I bought some and mixed them 50/50.
After I added water I pored it in a plastic cup.
I cut it out of the cup and yep it got fairly
hard. It is in the oven now at 200 F which is the recommended drying
temperature. I'll see if it dissolves in water after it drys thoroughly.
The next test will be two thirds plaster and one third corn starch
for a harder part.

-------------------------------------------------------------

Here is what it looks like after being dried.

This is a multi step process. First you make a model of the
part using foam or pipe insulation. Pipe insulation comes in two
diameters. 2 inch for p-ports and 1.5 inch for side ports.
Then you make a female mold split down the middle in two halves
for the Aquacore mandrel. RTV liquid rubber can also be used for a
female mold. That is perhaps better as it is flexible and the
model is easier to remove. It can be slit with a razor blade.

Then pour in the Aquacore and make as many
mandrels you are going to need. Then you dry the mandrels in the oven
for a couple of hours. You then seal them with something. Perhaps just
latex paint. Then you layup the parts over the mandrels. When the parts
kick out you soak the whole works in water to dissolve the mandrels
from inside the parts.

The 50/50 Aquacore softens and comes apart very quickly.

This whole procedure is labor intensive but the labor is cheap and unskilled :)

Next step is try a couple of different ratios of plaster to corn starch.

Paul Lamar

Paul,


Does the pipe you mention stay wrinkle free inside when bent.  If so here
is an idea.
Get some of that smooth lined flexible hose you mentioned.
Verify the course  near the engine and cut to length.
Make a hot glue foam block support frame to hold tube in desired location.
Take the hose off and cap one end.
Fill it with your homemade Aquacore.
Tap to remove air bubbles and settle the stuff.
Cap top and tape well.
Set it back in the form frame.
Put a cardboard box over the engine.
Insert (in the box) Robin's meat thermometer and hair drier.
Cut hole or flap to regulate temps.
After set-up cut the plastic hose off.

Tsu Rong in Japan

Yes

Does Tsu Rong translate to Fir Doug ? :)

Paul Lamar