DIY_EFI Digest V3 #95

[garfield at pilgrimhouse.com]

On Sat, 14 Mar 1998 03:27:59 GMT, cmorris at ix.netcom.com (Charles) wrote:

>1) anything that says Aircraft costs double or triple, just like
>hardware that says for Marine applications.

Often too true. One help is that Aircraft Spruce & Specialties (most in
X-aviation call them ASS for short; read on to see why) serves the
eXperimental aviation market, which can't command quite the enormous
markup of General (or Certified) Aviation.

Here's a tip about this supplier; they're notorious for mangling your
order, backordering nearly everything, poor customer service, etc. etc.
They are endlessly slammed by most on the X-aviation groups. I NEVER as
a matter of both practice and principal, order anything from them unless
I absolutely can't get it anywhere else, a very unlikely occasion these
days. A much better supplier is:
	Wicks Aircraft  800-221-9425
They are considered the "real" X-av supplier. I think their catalog ding
is also $5.

But it's nice to have an ASS catalog to compare prices! And there ARE
more items in ASS's catalog than Wicks.
	
>2) Aircraft can use a very heavy, thick-walled probe which is very
>vibration and burn resistant, because they are not interested in
>response time. I can't keep my 15-psi boost plus nitrous floored long
>enough for one of these gauges to stabilize - unless I can find
>several miles of straight, non-public road ;)
>Besides, I need to see that I'm running over 1600 degrees BEFORE
>frying a piston top or exhaust valve...

Yeah, I missed this key difference before. Silly me. One of the
commonplace annoyances of tuning EGT in an aircraft IS in fact the
noticeable delay between tweaking the mixture, and seeing the needle
move. Something like moving thick molasses. One thousand one, one
thousand two, and it's moved. OBVIOUSLY not suitable for loss prevention
in a turbo'd racing engine. Excellent point. Ya know, this happens alot
whenever you cross a "discipline boundary". Assumptions that work in one
domain are often no-gos, and sometimes even grossly the opposite, as in
this case.

Yes, we call them both EGT sensors, but all that's likely the same is
the underlying physics/electrochem. One other thing you can probably
expect is the aviation egt METERS are also probably pretty well damped
to avoid the needle being disturbed by turbulence & vibration. I would
wanna check the damping on any aviation meter to make sure it's gonna
respond fast enough, IF you try it in a racing engine application, where
seeing transients is far more important than eliminating a wiggley meter
needle.

Garfield