Modifying certified to experimental in Aus.-auto engining and avionics

Evening all.
I started a similar thread a while ago, but have done some more reasearch
since. I will be sending this post to SAAA, to see what they think.

As I understand it, you may put an auto engine into a certified aircraft in
australia, and the legislation states that a request to do so must be given.

SAAA seem to deal with substantial usage of 21.191(g) in relation to amateur
buuilt aircraft, that are major portion built. In this case, the aircraft
is built as a certified aircraft, an only the propulsion is experimental.
No problems. This does not apply here.

I wish to deal with 21.191(a) reasearch and development.
Under AC 21.1 -7.1.3 allows for (and specifically states) allows for R & D
on commercially or amateur built aircraft. Under this section, the CofA is
valid for only one year, or earlier if cancelled. This can be renewed for
further development.

After the completion of a R&D phase, the owner may apply for a 'special
certificate of airworthiness-experimental' certificate under 21.191(i),
which allows for private use of a previously certificated aircraft under
21.191(a). This is then valid for an unlimited period, as per normal
procedures for amateur built aircraft.

Also, CASA or an AP (Authorised Person) may issue this certificate under
instrument as stated in the legislation. Does this instrument state
specifically for authorisation under 21.191(g), or does it include all of
21.191 (a)-(i)? (Which in this case I think it would.) (Any SAAA APs out
there with an input?)

An example of this would be in the change of say a C172, to use a Holden
alloytec engine with a reduction drive. This engine develops about 190
something Kw of power, unmodified. Other engine/aircraft combinations could
also be used, ie:subaru EA81unmodified in a 152, EA81modified in a
warrior/archer, VW in a 150. Other things would be the use of a glass
cockpit in an aircraft. Remove the current instrruments and replace with
say, for example the Dynon EFIS 10A, and there engine management system.
This removes instrument clutter, allows for redundancy, as the screens and
inputs are interchangable. (Some Std instruments would be kept for safety
sake), but the sale of the other instruments would subsidise the cost of the
EFIS, $2100.00 USD. at the moment).

Yes I know there will be weight and balance differences, but am seeing
aviation dying due to the high cost of aircraft parts. There are also other
benefits, such as no shock cooling due to liquid cooling, auto engines are
more tolerant of bad fuel, smoother running, easier starting.

Please don't flame me on this one. I am looking at opinions, and whether
I'm going down the right track.
Thanks in advance for any replies.

Rob
Melbourne Australia.