Hi Chris,
I can provide one piece of second hand information and a lot of
sympathy....
With regard to the ceramic bearings, I was told that the extra expense
wasn't necessary, and that the 'big shaft' had been proved to hold up
on an aircraft, while no-one (he or I knew) had yet flown ceramic
bearings.
On the sympathy side - I can relate to your agony here. After blowing
two stock turbos and one modified hybrid (one of which was at 11,000'
and took out my apex seals) I was, shall we say, under a little more
pressure to get the decision right this time.
After studying turbo maps and specs and reading everything I could
find, I eventually took the same logic on the turbo choice that I did
on the engine rebuild and on aluminum welding -
"this is something you learn to be an expert in over many years,
not months. I do not have the time or tenacity to become a true expert
in this field, and I don't wish to employ the skills of an amateur (me)
.... so I need to use the skills of someone who IS a true expert."
Next problem - how do you know who is a true expert and who is just
claiming to be one?
I came across a turbo guy on the
http://canardaviation.com forum (the initial communications should
be in the archive) who was flying a turbo powered Subaru and seemed
like a true expert. I think he's in Canada. He'd been "into turbos" all
his life and certainly sounded like he knew what he was talking about.
I gave him all my specs in terms of engine, planned flight regime and
usage, and he came back with the list of goodies I now have. As with
all critical recommendations, I checked with others whose knowledge I'd
gained a healthy respect for. The Cozy Girrrls had independently
arrived at almost exactly the same choices, except that they wanted
more power at higher altitudes than me, so they choose the 9.6 aspect
ratio which would provide less on take-off, but more over 18,000'. I
had specified a max cruise altitude of 15,000'. Greg Richter also used
a Turbonetics, but without an auto wastegate. Leon in Aussie (another
true expert who used to contribute heavily to this list) agreed that
the specs and manufacturers were appropriate. At that point I put all
the agony behind me and purchased EXACTLY what I was told would work.
Thankfully (once I put the suction on the correct side of the wastegate
:) it did work and I've had no further turbo issues. The push in your
back on take-off feels like a Porche. I do the take-off based on the
manifold pressure keeping it below about 42 which equates to just over
half throttle. I think the late great Paul Conner said it best after
flying in Dan Crugar's 0360 powered Cozy IV, then taking mine for a
high speed taxi test.
"Wooooo!"
You, of course, have an advantage over me - You can follow and examine
my installation. The cost of a commercial flight into West Palm (or
Albany after early May) would be minor compared to the value gained.
You'd be welcome any time.
Regards,
John
--
Homepage: http://www.flyrotary.com/
Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html