Hello Thomas
"I was wondering whether anyone knows where those hi-compression pistons that
were
offered for the Rtx 912 some years ago"
I saw them for sale at E-Bay from these guys:
http://www.rotaxking.com/
The 912S is not only higher compression but a larger displacement (Larger bore).
I also saw a Bulletin from Rotax to not use any aftermarket pistons, I think
specific
mentioned was higher compression for 912s.
For better altitude performance on a 912, besides variable pitch prop,
installing
a kit to lean mixture with 2 EGTs and a Split second O2 Monitor would be my
choice as compared to boring and raising compression:
http://greenskyadventures.com/
Keep in mind with manual control if you lean at altitude in cruise if you
descend
and throttle back without richening, you will be running lean and could get
the engine to quit. The Split second will help out with that giving you a lean
picture the second you throttle back.
Of course adding a turbo makes the most sense, for the most "Cents".
Sincerely
Ron Parigoris
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