Here's a few photo of latest progress on new intake system. A
minor set
back in that this was suppose to be the plastic plenum/throttle body
mount/injector bosses. However, due to a little chemical process
called
exothermal (you fiberglass guys know all about this I'm told) produced
bubbles in the plastic resin, so the casting is not usable - expect to
make
a better mold and cast another one.
<Big snip>
Hopefully, I will have it completed this week and be flying with it
within
another week.
Best Regards
Ed Anderson
Ed;
Seems like a misnomer to call this a 'light weight' manifold; but then
that's just me - my 20B manifold weighs only 2 1/2 lbs. (Just had to
get that in :)
I can't help but think how very much lighter and stronger the part would
be if you made a male mold and did it with glass cloth layups. You
could even incorporate machined al fittings for injectors if you wanted,
epoxy bonds nicely to al. It would, of course, also do away with the
exothermic heating problem.
What kind of resin are you using? I'd be concerned about shrinkage
distortion, or possible cracking later. Or are you going to post-cure
this thing before cutting and installing?
Just my thoughts. I guess this may be a quicker/easier way to go to get
something done to see if it works.
Al
Ok, Al
Them are fighting words! {:>). I must admit that I am impressed with
your manifold for a 20B at 2 1/2lbs. So I went back out to the shop and
weighed everything.
Lower Manifold Casting (Paul's) = 3 lbs (after trimming)
Flange and tubes = 2 lbs 6 oz
Plenum/injector boss (Resin casting) = 1 lb 6 oz
Throttle body = 9 1/2 oz
four injectors = 14 oz.
Total = 8 lbs 3 1/2 oz for total intake
system
The only thing I can think of I did not measure was the fuel rail - a 10"
length of thick wall aluminum tubing, the AN fittings for the fuel line and
the bolts to hold the manifold to the block and such.
Now 8 lbs 3 1/2 oz for the total intake system might not seem too hot, but
my current one (same components weighed) comes in at 21 lbs. The boat
anchor lower stock manifold, the almost 5 lb 13B throttle body and tubes
inside tubes came to that. So I am quite pleased with the weight.
First, conceptually there is little difference between the Resin you use in
fiberglass and the resin I use, in fact you can get polyester resin and
epoxy tailored for casting. I added fiberglass fiber strands into the resin
before pouring to give it added tensile strength and reduce effects of
crazing which brings it even closer to your proposed fiberglass concept.
The resin I chose supposedly won't crack or craze, it has a hardness rating
of A95 which they
described as having some flexibility (resistance to chipping) and is very
impact resistant. It is also resistant even to acid. I have a chunk of
the hardened resin sitting in a container of MEK which was the most reactive
solvent I had handy, just to see the effect. There are dozens of type of
resins with characteristics approaching metal in strength and resistance to
chemicals and temperature. The more specialized ones are a bit more
expensive.
The fiberglass strands should hold the thing together and keep it from
falling apart. If it does start to craze and leak, I am confident I will
notice it (unexplained higher idle, whistling plenum, {:>), etc.)
I agree, you could certainly make a similar thing out of fiberglass and
resin and probably come in a bit lighter than 1 lb 6 oz for the
plenum/injector bosses. But, with the 4 injectors along weighing 14 oz, I
feel it is reasonably light.
How will it work and stand up to under the cowl environment. I, of course,
do not know at this time. However, time will tell (and I will keep the old
intake system stuck in the closet for a while {:>), just in case)
Ed Anderson
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