Intake manifold construction

[Frederic Breitwieser]

> biggest unknown.  I wouldn't expect thermal expansion to be a significant
> problem except possibly at the bolt holes, where thermal expansion might
> cause clamping forces to vary.  Vibration is likely to be the biggest
> source of trouble, and I really haven't learned much about how composite
> materials behave under cyclic loads.  It's probably governed by some
> hideously complicated equation anyway. But I'm pretty sure that a
> fiberglass manifold is a workable possiblility.  After all, boat hulls have
> to deal with vibration too.

Actually, you touched on some good points.  If you lay the matt the
right way, or ways, composites can be very strong and tolerant of
vibration.  The vibrations on any engine are not that great, considering
race cars and leman's suspension pieces (some anyway) are composite, and
they hold up to many PSI of force in a variety of directions.  These
pieces are also made by professionals/experts/masters of the trade.

My first sheetmetal aluminum intake for the Buick V6 was extremely
flimsy.  When it was detached from the engine, I could have bent it up
real bad with my bare hands.  Bolted to the engine, it was fine, even on
the dyno at 7-8k RPM.

I think the biggest issue with composites is construction... when I made
my carbon fiber intake (which I started to say in the previous message,
which got screwed up) I made the intake out of paper first, then layed
the mat on that, and sprayed resin.  Repeated with mat in different
directions.  Then, when complete, I burned the paper out, which was
really easy.  Sprayed in some isopropol, lit it, then hosed off all the
residue, and cleaned it out with a bottle brush.  Probably not the way
the professionals do it.  I ended up with cracks and other problems, but
I will say it was definately due to my inexperience with the material. 
I bought into the various websites I've seen where they make it look so
easy.  Its not, its definately a job for someone meticulous and
patient.  Neither of which I am :)

Its also different than consructing a row-boat.  I had helped a friend
make a fiberglass rowboat years ago and remember it being very easy. 
Yes, it was.  Large mold, chopper gun, professional tools all around. 
Large flat surfaces like rowboats, hoods, trunk lids, etc, are easy to
make in a wooden mold.  Small tubes that curve and are complex for other
reasons take a lot of careful layup work.  Not to discourage anyone, I
think its a fantastic idea, just not something the "average guy" would
make in a day in his garage.

-- 

Frederic Breitwieser
Xephic Technology
769 Sylvan Ave #9
Bridgeport CT 06606

Tele: (203) 372-2707
 Fax: (603) 372-1147
Web: http://xephic.dynip.com/
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