Jeff Spitzer wrote:

Also nitriding the top of a heat treated 4130 seal might also
work and that would be a LOT cheaper.

I just don't think those cast iron seals are the optimum solution
for turbo engines.

The silicon nitride ceramic seals are nice but they can be
fractured by detonation as well and they are very expensive.

Paul Lamar

Beware.  The path to successful rotary engines is littered with bad apex
seal to rotor housing material compatability problems.   There is a very
fine line with friction and oil retention vs mass related to chatter.  The
cast iron seals will have lower friction than a 4130 one.  This is not as
cut and dryed as it looks.

Jeff Spitzer

Hurley Engineering claims he sells more seals than anyone and they
are made from mild steel. He also claims they are softer than the
Mazda surface hardened cast iron seal hence easier on the housing.

I also thought of the mass issue. Perhaps a bunch of  little holes 
can be drilled side by side in the back side of the 3 mm steel seal 
with an NC mill to lower the mass. Should still be cheaper and tougher
than the ceramic seals.

Paul Lamar
 
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