I understand you
> need the E model and the High and Hot modification also.

I'm not exactly a turbine expert (but I slept in a Holiday INN Express
once), but I am building a IV-PT and using the 601D. There are only very
minor differences in the D and E. The E is certified if -11 model and has 25
more HP for takeoff ONLY. Continuous power rating is the same. I doubt that
a IV-P will see any difference in takeoff performance between 725 and 750
HP. If 725 won't get you quickly in the air, well, you ain't gona make it
all. A stated, ITT management is the critical factor with this turbine. You
will never get near torque limits. The "High, Hot " version is for high
density altitude performance ( read this takeoff at high density altitude").
It will not show significant benefit at cruise. For those of you who are not
into conspicious consumption, ( you can call it frugal, or you can call it
cheap, I prefer thrifty) John Cook in Deland will sell you a core D (or E if
you prefer). The D core is 15K. He will then IRAN the turbine and use his
intimate knowledge of the engine to maximize the power, smoothness, and
reliability. The IRAN is 16.5 k. This will give you a ready to go turbine
for ~32k. Complare that with a an IO-550 at 58k or E from Walter ( which is
a 2nd or 3rd rebuild) for ~90k. I'm sure that some will feel that the
economy is ridiculous and that somehow the Walter people make a superior and
safer product. I would counter that you should talk with and visit John and
judge his knowledge and expertise before you decide. I know that Lancair
certainly relies on his advice. Those that feel that only a factory can
properly build a product should reexamine there thought process. How can
they allow themselves to build a kit plane?

I personally can't afford to use the E engine. I'm glad that some have that
means. I'm sure that it is a fine turbine. I'm sure Garretts are great too,
but that's another whole magnitude of expense.

All are far more reliable than piston engines. Actually European studies for
justification of single engine turbine transport use, indicate that it is
lukely to suffer a double piston engine failure in a twin than a single
engine turbine failure. The only 2 Walter 601 failures in the US occurred
with the E turbine, but this is merely a coincidence, since for all
practical purpose there are no significant operational differences.

Yeah, I think the jet in the tail idea has been tried by the miliary, it was
called a SAM, I think.

Just my opinions,
Tom Hall
N725PT