Richard Riley wrote:

Sometime recently (last 6 months or so) there was a post about how
much a well done auto conversion costs. The point was that if you're
doing it right - rebuild with race quality parts, proven PSRU, etc -
that the initial installation isn't significantly less than a zero
timed LyCont. (I think it's accepted by both sides that a rebuild
will be significantly less for the auto conversion, but that wasn't
the point)

IIRC, it broke down the costs to pretty small details. I've googled
but can't find it. Does anyone remember it, or is this a figment of
my sleep deprived imagination?

I don't have a current interest in this issue ... yet!

However, when I do get started building, this will be a major issue, and
I have been reading, talking to chapter members and others, and even
contributing my 0.02 on occasion for some time.

Originally, I believed that the best way to convert an automotive engine was to
flip it over and drive directly through a quill shaft, in the manner of Steve
Wittman's conversion of a Buick/Olds aluminum V8 for the Tailwind. The lighter
castings in more recent 90 degree V8 and V6 iron block engines made the idea
seem reasonable for a long time. However, those relatively large, slow turning
engines that develop their peak torque at less than 3500 rpm are rapidly
becoming dinosaurs, and any dream of a retractable nose wheel starts to look
really nasty!

I still like auto engines, but doubt that the more modern ones will benefit from
the "conversion" process. Everyone who has posted here, and who claims to have
manufacturing experience, claims that they are routinely run at maximum rpm and
horsepower for extended periods during acceptance testing of the designs,
including some really atrocious warm-up procedures, and the major concern (and
proven failure mode) is the head gaskets. Therefore, the addition of racing
parts does not seem productive from my viewpoint, with the possible exception of
the head gaskets. Assuming that unleaded fuel will be available, at least most
of the time, every ECM being supplied is so much better than my own engine
management can ever be that there is no contest.

Therefore, my most recent thinking is leave the engine completely stock,
including all harmonic balancing and damping components; and supply it with an
offset reduction drive. Just my 2 cents.

Peter

Additional disclaimer: Just my current thinking, and a reserve the right to use
one of those heavy old inverted engines--resulting in a two seater with the
weight of a four seater ... or to consider a certificated aircraft engine.