Marc Wiese wrote:

Subject: Re: (rx7) in new engine break

Some of the Japanese engine builders are using a spray-on "coating"
which
effectively allows enough sealing to start a new motor right up.
Naturally
it rubs off eventually and is apparently not harmful to the engine in
any
way.   FEED's site, I believe, shows this.   (www.pac-gate.co.jp/feed)

On another note, do combustion chamber pressures help the apex seals do
their
job or do they simply rely on spring pressure for sealing?   Piston
engines
do have a fine hone (much more so than 10 or 20 years ago) to the
cylinder
wall which is worn away in the first few miles of usage.   Some theorize
that
breaking in a piston engine "hard" produces better ring to cylinder seal
and
a motor which will produce more hp than a "lazily" broken in motor.
This
theory is pretty popular in the sportbike community presently.

Since there is no "hone" on the housings, is there anything really being
worn
away or is it a matter of seals "settling"?   Specifically the apex
seals.
It would seem the side seals go through something similar to piston
rings on new or lapped housings?<<<

Marc Wiese

Marc,

    I don't know the answers to your questions, however, both Tracy Crook
and I agree that our engines appeared to improve in the power department as
we fly.  Tracy commented that his engine appeared to improve up to around
the 250 hour point.  I can definitely produce more rpm (5200-5300 static)
now (200 hours)  than when I first ran the engine (5000 rpm then ).  So it
appears that something does seal better with time and use.

Ed Anderson

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