Ed, how is your intake manifold coming. I am intensely interested
in how you are going to configure the business end.
Here is a picture of Dave Lemons Production 2nd gen
convertible road racer. Now that is a serious air supply hose :)
Paul Lamar
Boy! that is one serious air intake. However, I am working on one that
might rival it {:>). I have completed the plenum casting mold and cores and
was prepared to cast the plenum today - however, when I did my calculation
of how much resin I needed, I found I was about 20 cubic inches short - so
have to order another jug of the stuff. So probably won't be able to cast
until later next week.
But, in the mean time here are a few photos of the progress - boy, I now
understand why dies and molds cost so much - lot of man hours to produce one
(even in foam).
Some photos of the molds now ready for casting. The core held up against
the tubes so you can get some idea. The injector bosses are integral to the
plenum (on the rear side of the plenum. The front is a blank plate so that
I can put anything from my 3 throat mazda throttle body, to the Mustang 70mm
(see in photo) or my 94mm (3.5" dia) one I am making out of a section of 4"
aluminum tubing, an old butterfly shaft and will braze the tube to a
mounting backplate of 3/8". There is a photo showing the Mustange and my
creation together for comparison. The front plate of the mold is cast with
no opening (intentionally! {:>)), that way I can cut the size hold I want
down to the plenum tubes when I decide on which throttle body..
The mold body is high density foam painted with an acrylic paint to seal it
and the cores are silicon rubber so I can wiggle them out of the casting
once its harden.. I will be using a type of polyutheran? resin with a shore
A95 hardness - rated as a hard but flexible material resistant to chemicals
including diluted acid (of course they don't say what type or how diluted).I
will mix fiberglass fibers into the resin mix before pouring it to give it
some additional strenght.
This is an experiment to see whether some weigh and space can be saved by
intergrating the plenum, throttle body mount and injector bosses in one
part. Actually, I guess you would say there is really no plenum - just the
connecting tubes. Then the last thing is to drill for the injectors ( I
initially attempted to cast cores for the injector holes but it just got too
complicated to ensure alignment ( of the floppy silicon injector cores in
the mold) for the fuel rail, much easier to align entire casting in a
drilling fixture {:>).
So been busy, and close but no cigar yet. Thanks again for the casting,
made it all possible!
Ed
You do nice work Ed. This is a grand experiment in manufacturing intake
manifolds. What other types of resins are available for this kind of work.
Most of the production plastic manifolds are made from nylon as I recall.
Who is your source for these casting resins?
You will get the same power at 6000 RPM if you shorten the total
loop length to 17 inches. In other words from one outside port to
the other outside port. The distance from inside port to inside
port will be less which will tend to broaden the effect over a range
of RPM. That should save some weight. As your design is now it is tuned
for 3000 RPM and is working as a conventional tuned pipe manifold
at 6000 RPM. Rough numbers of course. The same as the Mazda stock
manifolds are designed to do.
The fact that most dynamic chamber designs we have seen so far
for four or six port engines have different loop lengths
for the primary and secondary ports tends to broaden the HP curve
at the expense of the peak power obtainable with a simple high Q system
with all runners the same length.
I will shortly up load a 3D design for a peripheral port dynamic chamber
that inherently solves this particular problem.
Paul Lamar
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