Corky Scott wrote:

On Fri, 21 Nov 2003 17:41:37 -0600, Big John
wrote:

Corky

Have you enough ammunition on auto engines to stop the nit picking in
this group? Both Lyc and Con started life with auto engines G

Big John

Big John, to the best of my knowledge, I try not to nitpick. I try to
present facts as I know them.

I believe that there are various auto engines that can be successfully
converted and I believe it strongly enough that I'm assembling a Ford
V6 in my shop that will be the engine I fly behind.

You weren't here when this subject was first aired many years ago, but
there were many sceptics... actually that's not a strong enough word.
There were some extremely vocal critics of the concept who felt that
no auto engine would work in an airplane. One of them was an auto
engineer, a guy who used to work for the Chaparal Racing Team with Jim
Hall. He was absolutely positive that V configured auto engines would
disintegrate (literally) under the stress. He also believed they
could not cool because the coolant passages were too small and the
cylinders too close together. He was wrong.

In order to build a reliable auto conversion, you do have to do your
homework. You have to safety wire just about everything that could
come off including the oil pan bolts. You have to build using
accepted aviation practices. There have been guys who screwed gas or
oil lines into the block and then ran them to the firewall. They
broke. You can't mount pipes solidly to the block and run them for
any distance, prop vibration will eventually crack them.

The guy who developed the Ford V6 discovered that the stud that holds
the air filter can and will unscrew and drop into the engine, if you
don't safety wire it. How did he discover this? Because it did. It
was one of the many flights in which he coasted back to the runway.

By now, many guys have successfully built and flown the Ford V6. One
guy accumulated more than 2,000 hours without anything falling off or
failing. Others are in the over a thousand hours hobbs time category.
For some reason, success stories like this don't seem to matter to
those who feel using an auto engine won't work.

I do intend to test run the engine extensively. I'm fabricating an
engine test stand along with the engine assembly process. While it's
true this doesn't exactly duplicate the stresses encountered during
flight, it's the best I can do, and better than just hanging it on the
airframe and testing the engine during the very first flight. One
thing at a time please.

Corky Scott

First, I apologize for the delayed posting in the middle of a thread.
I can only say that it has been a strange week ...

My personal view, not fully substantiated be research, is that most
(and possibly all) of the current automotive engines can be successfully
converted for aircraft use. However many of them have shortcomings that
make them less attractive.

I might not bother with an engine that I expect to have significant
vibration modes other than torsion. For example; I doubt that I would
convert any of the three cylinder engines, even if it had balance shafts,
as an inline four could be a much smoother installation. My hypothesis
is that the pitch oscillation of the three cylinder, and possibly some
of the 90 degree vee six, engines would add stresses to the propeller
and PSRU. OTOH, there are a lot of 90 degree vee six engines flying...

Probably the best question is not whether an automotive engine can be
made reliable; but whether a purpose-built engine is available and
competitively priced for the application. For example, Jabiru offers
ram air cooled engines of 80 and 120 horsepower; provided that the
aircraft is fast enough to use a 60 inch diameter prop. Rotax offers
engines with a hybrid cooling scheme...

As I recall, Blanton's conversion was originally for glider towing.
According to the story I was told, the reduction drive allowed the Ford
vee six to produce thrust similar to a much more powerful direct
drive aircraft engine--at towing speeds. Unfortunately, the story
later circulated that the engine produced mathematically ridiculous
amounts of horsepower...

So, I may eventually build with an automotive conversion. Or may not.
The choice is not "open and shut".

Regards,
Peter