Hello  Paul,

  Here are four pictures of P-port and the in-housing  injection
holders.
  This housing is one of several scrap housings I am  machining to get
the
  entrance angle and component dimensions finalized.  These four
pictures
  are from last August's work and don't show the finished  bores yet.
  The P-port will have an outer step bore similar to the  injector
  holders.
  I am extremely happy with the hardness  and toughness of the DEVCON
Al
  product.  Only one trouble is the  consistency is a little softer
than
  taffy so as you can see, it is easy to  end up with inclusions.  If
you
  work fast and use a technique like  applying frosting on a cake, then
  good results can be obtained.  Any  hole can be drilled out and
filled.
  The company sells another slightly  softer epoxy that pours.  I
  assume it
  has more solvent  in it.

  I was very happy with how the injector area worked out and was  able
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 preexisting  epoxy when roughened up
a
  bit.  As you can see it sticks well to  prepared alumunim and is damm
  near as hard.  It machines VERY  nice.

  Can it done with your straight-in approach?Yes why not?   Bend up
  some
  thin aluminum sheet into the proper wedge  profile.  Alodize it. Fix
  this
  fence in place with hot  glue gun on the outside.  Epoxy should be
made
  extra high and milled  down to final dimensions. To save expensive
epoxy
  add a 40mm wooden or  plastic dowel in the area where the inlet will
be
  bored.DO NOT PREHEAT to  make it easier to pour.  Follow the
  directions for best  results.

  Doug in Japan

  That 12.5 degree tilt looks like a real  mechanical advantage.
  I hope you can find a dyno over there to get some  good numbers
  on the pros and cons of your version. BSFC and  HP.


  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 what  you are driving at. That might work.
  I'll have to do a 3D and  see if that is feasible.

  Paul Lamar

  Paul,

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

  Doug Fir


  I would  like to point out that the bypass ports I built  into 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 the  whole
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 so  the 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

Paul,

Is there any merit to a .005" interference fit between an Al tube and
the rotor housing using LN2?

Joe Berki

You have to be careful you don't stretch or warp the housing. .005
inches would result in a major leak in the sides of the housing where
the water O rings are.
IMHO it is not worth it. The SS tube tig welded to the liner and the
conformal aluminum plate is straight forward and highly likely to work
with easy leak repairs in the remote chance you even get a leak in the
outer housing.

BTW a pound of Devcon pour came into today but I will probably use it to
make a casting pattern for the conformal aluminum plate. It was about
$56.
Larry has a new casting supplier he likes in Northern CA.

Paul Lamar

Paul,

Before you start please understand one point.  One of the main reasons
I went with a process of adding epoxy to the aluminum  housing was I
wanted the chemical bond between the two creating a homogeneous
epoxy/aluminum housing.  This was to ensure  that four M5 (3/16") studs
that will hold the   throttle assembly  had enough material to tap into.
 If you examine the housing area on the lower part of your bore and
about seven to ten mm in from the edge  you can readily see that the
sloped housing profile is only about seven mm thick.  Not enough for a
blind tap unless you are going to pot the inside of the cavity as well.
 However with a  epoxy material added on top of the housing you will
have added at least another six mm in thickness.  On the other hand
slapping on a cast epoxy wedge with screws and silicon sealer will
ensure that you lose the strength advantages of the composite as well as
needing to screw into something that is screwed on to the housing.  In
the end to have a perfect aligned fit you are going to have to machine
the housing  with an end mill.  Please don't tell me you are trying to
promote a quick and cheap drill press method  P-port:)

Doug in Japan

Well no. Here is the plan. Mill off some material off the housing down
to the outer wall with the housing in the mill at 90 degrees.
Same as if you were boring the final hole. Screw this aluminum casting
(3D 1) to the out side of the housing. Screw holes or screws not shown
yet. Then bore the 2 inch hole for the SS tube to be welded to the inner
liner.
Weld the tube. Unscrew the casting slip it off over the tube and cover
the inside with red RTV and the bore with red RTV.
Replace the casting. Your done. Expansion and contraction will not be a
problem as it is accommodated by the flexible nature of RTV.

I'll get a bunch of these casting made and sell them.

Paul Lamar



This thread has the feel of progress about it.
Decker, Michael