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.

----------------------------------------------------

I changed the plan slightly. I was having too much trouble coming up
with a valid solid model for the casting pattern so I simplified it.
The down side is you will have to do a little die grinding on the rotor
housing to clean up the valley so a simpler plate will fit and work.
Let me me know if you want a stp file or iges.

Paul Lamar