HelloPaul,

Here are four pictures of P-port and the in-housinginjection holders.
This  housing is one of several scrap housings I ammachining to get the
entrance  angle and component dimensions finalized.These four pictures
are from last  August's work and don't show the finishedbores yet. The
P-port will have  an  outer step bore similar to theinjector holders. I
am extremely happy with  the hardnessand toughness of the DEVCON Al
product.Only one trouble is  theconsistency is a little softer than
taffy so as you can see, it is easy  toend up with inclusions.If you
work fast and use a technique likeapplying  frosting on a cake, then
good results can be obtained.Anyhole can be  drilled  out and filled.
The company sells another slightlysofter epoxy that  pours.I  assume it
has more solventin it.

I was very happy with how the injector area worked out and wasable to
get  the correct and final dimensions with this one housing. As for the
P-port  area I had to add about 6mm more along the bottom for the slide
throttle  to  be supported correctly.For this test work,adding epoxy is
not a problem as  it sticks to a preexistingepoxy when roughened up a
bit.As you can see it  sticks well toprepared alumunim and is damm near
as hard.It machines  VERYnice.

Can it done with your straight-in approach?Yes why not? Bend up some
thin  aluminum sheet into the proper wedgeprofile.Alodize it. Fix this
fence in  place with hotglue gun on the outside.Epoxy should be made
extra high and  milleddown to final dimensions. To save expensive epoxy
add a 40mm wooden  orplastic dowel in the area where the inlet will be
bored.DO NOT PREHEAT  tomake it easier to pour.Follow the directions for
bestresults.


Doug in Japan

That 12.5 degree tilt looks like a realmechanical advantage.
I hope you can find a dyno over there to get somegood numbers  on the
pros and cons of your version. BSFC andHP.


Paul Lamar

Paul, With this approach why not bolt two housings together with a
center section between and the dowel pins then machine  that assembly
P-port section flat so that a slide throttle can be  hard mounted
directly to the Housings?

Fred O.

I think I see whatyou are driving at. That might work.
I'll have to do a 3D andsee if that is feasible.

Paul Lamar

Paul,

I bought the taffy consistency product. As Lynn mentioned years  ago,
and  repeated yesterday in almost thesame words, the product held up in
the  exhaust port area inhis kart motor.

Doug Fir

I wouldlike to point out that the bypass ports I builtinto Power
Products  engines using Devcon Plastic Aluminum, move fuel air mixture
from the  crank  case to the cylinder, and as such were cooled during
operation. The epoxy  was exposed to high temperatures after shut down
as thewhole engine  normalized the hot and cold sides. I have also
potted Pport tubes (carbon
steel) in place and never had a leak. I have not attempted to use
Devcon  in  or near exhaust ports. I doubt that it would hold up for
very long in that  application.

Lynn E. Hanover.

I am going to try Doug's idea of putting epoxy on the outside  to make
a flat area for an O-ring outer seal. If it leaks  in the future it can
be more easily repaired. I'll buy the high  price liquid aluminum Devcon
product but I am willing to bet it  is no better than JB Weld. I'll heat
one puck of JB Weld and another  of DEVCON in the oven at 500 F and see
what happens. My money is  on the JB Weld :)


The welded SS tube to the liner will be retained.

Paul Lamar
--

Paul,


OK but that may not tell you much as in application if your intake port
gets  up to 500 degrees I think your engine will have bigger problems:)
I take  it  you are concerned with thermal soak after the engine is shut
down?This  could  be a problem with an unshielded exhaust system nearby.
I would be more  concerned with comparing the compressive
strength,hardness, thermal creep  characteristic, and toughness.

Are you going to retain the straight-in approach?If sothe upper wedge
of  epoxy will be about 15mm high.I suggest you put a metal dam there.
Best is  a  three side dam that conforms to the housing.This was the
next experiment I  was going to try.It can be one piece stainless that
is bent.Done properly  it  will look nice as well and of course can be
milled as well.



Doug in Japan

Yes. I will keep the straight in approach.

Paul Lamar

The heat soak issue is a real potential issue. I discovered today that
my manifold lines are melting on the intake tube fittings. This is not
happening during run time - the intakes are ice cold. The heat soak
after shutdown is something to behold as the intakes go from cold to
hot hot hot. The MP lines become hot & gummy.I've also noticed that  the
unshielded engine mount tubes are too hot to touch while the  engine is
running.

Mark (Rocky Mtn High)

You need red silicon hose on those manifold pressure lines.
Either that or braided teflon lined hose.

The motor mount tubes on my C182 also require heat shields.

BTW that Harbor Freight vac pump does not have a vac gauge.
You are going to need one.

Paul Lamar

Paul,

Here are two small PDFs file showing the technical characteristic of
Devcon Al putty and liquid.
Liquid is superior in every way except flexible strength.I'll be
ordering some of this stuff next.
It would be nice to have the same data for JB Weld which doesn't have
the product line, that Devcon has.

Doug in Japan



 Paul,
 look at the coefficient of thermal expansion on the liquids. All else
being
 the same, take the liquid steel for it's lower thermal expansion.
 The thermal expansion difference between the potting compound used and
the
 aluminum housing is the highest stress it will see.
 It still expands more than the aluminum, but is far better than the
liquid
 aluminum compound.
 Larry


JB Weld is steel filled.  The other thing I have considered is make a
lost
 wax casting of a conformal aluminum filler block. No NC mill profiling
 required. Use an epoxy casting as a pattern.  Machine screw it down
with
 RTV under it to the outer rotor housing. If it is tall enough that is
all
 you need. No O-ring and easy to reseal. This would be the most
reliable way
 of doing it. No room for error.


 Paul Lamar


I think this is the best idea yet..  The parts are going to move around
because of CTE, so you might as well allow for it (with RTV and
O-rings).


Regards,

Matt-

Paul
 do you have a diagram you could send me on where exactly to bore the
holes for P-Porting a 13B?

Mike C.


Yep.
Here they are.
http://www.rotaryeng.net/fund-of-intake.html
http://www.rotaryeng.net/Welded-steel-p-port.html

Paul Lamar