My article you cited (The Christmas Engine) can be found at...

http://wapurl.co.uk/?IWL54GJ

...and I suggest you give it another read, paying particular attention
to the difference between PEAK and SUSTAINABLE output, and how long
you can expect to pull the former... if you're interested in a
reasonably long TBO.

I very much will.

As for the question of direct-drive vs a PSRU, I'm afraid you're a bit
behind the power curve, engineering-wise. *Adding a PSRU does not
change the laws of physics which dictate the power & durability of an
engine.

Hold on a second. First, I am behind the power curve, engineering-
wise. I'm not a mechanic engineer, nor have I tinkered with VW (or
other engines) for years. So that puts me behind.

*The use of a PSRU can allow a small engine, such as the
1300cc Rotax, to produce a prodigious amount of power, but only so
long as the waste heat is properly managed, which Rotax does by using
liquid-cooled heads... and lotsa money :-)


This was the gist of my commen on PSRU. I wasn't speaking to the
cooling problem.

I notice that Great Plains offered liquid cooled heads in their 2007
catalog but not in their 2008. Hmm...

As for your expectation of discovering "the truth" by popping up on
the internet and polling the readers, you're about to get a valuable
lesson in human nature. *After having paid $6000 US for what is
basically a $2500 dune buggy engine with a fan on the nose, an awful
lot of people are going to swear on a stack of Bibles that the
miraculous claims of power and durability that caused to spend that
amount of money are ALL TRUE. *Never mind that their Specific Fuel
Consumption is 0.562 (or worse), or that they have to 'touch-up' the
valves now and then... *because if that miraculous amount of power and
that remarkable TBO were NOT true... it would mean they were suckers,
being preyed upon by another EAA-endorsed huckster. *And of course,
that can't be right.


I put "the truth" in quotation marks on purpose. For reasons you
allude to.

For everyone else, as I said at the out-set this isn't a new topic.
Dig around, you'll find lots of valuable, quantified information here
and in the archives of the AirVW Group. *You will also find lots of
the other kind of information as well, including full-page ads in
early issues of 'Sport Aviation,' along with infomercial 'articles.'
Read it. *THINK FOR YOURSELF. *Your life may literally depend upon it.

Thanks, I'll look for it.

The saving grace in all this is the fact an engine is incapable of
lying. *Build it, fly it, and what you see is what you get. *Oddly
enough, what you get will come remarkably close to what physics,
thermodynamics and engineering has SAID you will get -- and have said
for the last hundred years.

-R.S.Hoover

What are the best VW books in general? I'm working through the one by
Tom Wilson, but it doesn't cover these issues we're talking about.
Great Plains offers a VW conversion manual, is it good? I've looked
for VW aero-conversion books online but haven't found much.