X-Mozilla-Keys:                                                                                 

Jim Dana wrote:
 Paul:   nikasil coatings are put on by aircraft cylinder remanufacturers .
It isn't this process I am concerned about It ti the warpage , sealing and
cooling of the housings.The design of these pieces becomes more critical than
the wear coatings!  JIM DANA

 Paul wrote:
The other problem you are going to run up against is shrinkage
of the aluminum housing when they get too hot  because the steel
tension bolts holding the engine together expand at a lower rate
than the alloy housings.

snips.....

 Here is an idea for you. Since the tension bolt problem is
causing the rotor housings to shrink when the engine is overheated
and the problem would get worse with aluminum end housings I suggest
a little low cost R&D.

Get a Mazda tension bolt. Get a piece of thick wall aluminum tubing
with approxmately the same ID as the Mazda tension bolt.
Clamp the tubing with the bolt and a nut.

Heat it in a kitchen oven to 200 degrees for an hour or so to
allow everything to stabilize.

Remove from the oven, let cool  and measure the length of the aluminum
tube.

Increment the oven temp by 10 degrees.

Repeat the test until you discover the aluminum tube has
been permanently compressed. Note the temperature at which
this happened.

Simulate a 13B rotary engine by using alternate cast iron and
aluminum spacers.

Repeat the above test.

Now try Belleville springs under the head of the Mazda tension
bolt.

Repeat the test.

Report the results on here.

If you can solve this problem proceed with the design of
the aluminum end housings.

BTW Jim you can get Belleville Washers springs from 
W.M.Berg 1-800-232-BERG in east Rockaway N.Y.

The .380 ID version has 235 pounds force when compressed
to .049 high. It starts out at .059 inches high. 
When totally flat it is probably history but
the thickness would be .040.  Better that than
destroy your rotor housings.

The .505 ID version has 340 pounds force when compressed
to .062 high. It starts out at .075 inches high. 
When totally flat it is .050 thick.

You can stack these to double or triple the force.
You can flip them over and run them back to back 
to  halve the force with twice the deflection.

It is a little tricky to install these as the bolt torque
has to be just right. It is better to use a depth gage
and measure the height of the spring when installed
at room temp. The height of the spring will then
determine The preload on the bolt and the amount of
rotor housing thermal expansion that can take place before
the Belleville washer spring bottoms out.

All this is really in the category of extra over heating
insurance in the stock cast iron/aluminum version of the 13B.
It may be essential however for the all aluminum version.

Paul Lamar
 
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