<<I am installing a 500 hp Zehrbach engine in my IVP also.  Direct drive,
liquid cooled inverted V8, electronic fuel injection, electronic ignition,
ceramics.  650 cubic inches.>>

I have been an "engine design hobbyist" for many years, and I have concluded
that for our size aircraft the ideal piston engine configuration is the
inverted direct drive turbocharged liquid-cooled V8.  It has the potential
for greater power/weight, more reliability and less noise than existing
engines.  I think the Zehrbach approach is close to the "correct" one, but
not quite.  I don't see the value in the dry sump or the long propshaft
extension.  Also, for lower-powered applications like my ES it looks like a
bit of an overkill.

Gary Casey