Bill,
Fantastic picture!

         I hope the real manifold looks half as good as the CAD
rendering.

Look back over the published data, then look at the Mazda intake at
full blast, and you will come to the conclusion that for our purpose
very short runners are best , the Mazda manifold lends itself to
cutting and welding, whilst retaining the injector mouldings and fuel
rail. What could be simpler? We just have to convince Tracy that 3
injectors are better than two.

         The stock long runners make 247 HP. From what I have seen,
short
runners have yet to make over 200 (at under 9000 RPM.)

         The stock manifold is REALLY heavy. I suspect that the heavy
aluminum casting was chosen to reduce noise.

         I thought hard about using some portion of the stock manifold,
but
it really doesn't reduce the overall effort, once you have elected to
use carbon fiber composite for the rest of the manifold. You have to
mate up the composite using a flange of some sort. If you retain some of
the stock manifold, you must fabricate a flange on it to mate to the
rest of the manifold. It is simpler to build another 6 inches of
composite manifold. This way, you skip the process of carving up the
stock manifold and attaching some sort of flange to it.

         I also evaluated using the plastic portion of the stock
manifold.
After I modeled it up in CAD, I discovered that it won't quite fit under
the cowl. It's close, but it doesn't _quite_ fit.

         Bill Dube'



Bill, please credit the people you are quoting by including their names
at the end of their quote. Also it helps the new people on here if you
quote the entire message.

People have had problems in the past with all plastic runners.
Heat soak after a run can be a problem. Some have been known to burst
when the inevitable back fire happens. I think Tracy experienced that
problem as I recall.

Paul Lamar

Chevrolet is doing okay with plastic intake manifolds - LS1 - Corvette
engine at least.  It should be no problem to make a composite manifold at
least as strong as an aluminum one.  Heat soaking is a different issue -
one of materials (resin) selection, manufacturing process (to achieve hi
cure temperature (eliminating 'creap') while maintaining dimensional
stability) and protection.  The rotary will require an effective heat
shield (protection) between the intake and exhaust - probably regardless
of the manifold material selection.  A v8 engine is easier to control the
temp for because the intake resides on the opposite side of the cylinder
head from the exhaust - a good heat shield.

As a side note, backfiring seems like less of a risk with a slide throttle
at the rotor housing.

As another side note, I can't really understand why people are messing
with side port intakes..  Unless you are going to take everything out of
the RX7/8 engine compartment and bolt it directly to the firewall of your
RV - manifolds, EVERYTHING...  Virtually everything about making an
aircraft rotary seems easier/better on the P-port.

Paul, would you rather see our replies at the top of the message body or
the bottom?


Regards,

Matt-

At the bottom Matt. Thanks for asking.  The slide throttle back fires real good if you get it too rich. Shoots flame out of the intake tubes like a blowtorch :)


Paul Lamar

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