Avoiding Shock Cooling in Quick Descent

O.,

all the engine management columns by John Deakin are a must read. There
are many more at Avweb.

--
Thomas Borchert (EDDH)

Thomas,

Thanks for the pointers. The articles are indeed quite good, but there
is something I do not understand. It seems the whole theory on LOP
operation is conditioned on having GAMI injectors, because the article
implies that you can not do LOP operations on "normal" engines because
of uneven fuel distribution causes roughness due to different cylinders
outputing different powers when you start leaning past peak. Am I
missing something here? What percentage of planes actually have GAMI
injectors?

-Sami

Thomas Borchert wrote:
O.,

all the engine management columns by John Deakin are a must read. There
are many more at Avweb.

"O. Sami Saydjari" wrote:
Thanks for the pointers. The articles are indeed quite good, but there
is something I do not understand. It seems the whole theory on LOP
operation is conditioned on having GAMI injectors, because the article
implies that you can not do LOP operations on "normal" engines because
of uneven fuel distribution causes roughness due to different cylinders
outputing different powers when you start leaning past peak. Am I
missing something here? What percentage of planes actually have GAMI
injectors?

The 1997 Cessna 182S that is new to the club I am in flies LOP quite
easily. To the best of my knowledge, this is a stock engine (not GAMI
equipped). It is only advantagous to fly this way if you are flying LONG
legs. The corresponding drop in cruise airspeed is not suited to short,
fast trips.

"O. Sami Saydjari" wrote in message
...
Thomas,

Thanks for the pointers. The articles are indeed quite good, but there
is something I do not understand. It seems the whole theory on LOP
operation is conditioned on having GAMI injectors, because the article
implies that you can not do LOP operations on "normal" engines because
of uneven fuel distribution causes roughness due to different cylinders
outputing different powers when you start leaning past peak. Am I
missing something here?

No, you're not. You're seeing a good example of just how sloppy the typical
FI systems are.

What percentage of planes actually have GAMI
injectors?

GAMI has sold about 7,000 sets of their GAMIjectors, so figure that against
the entire fleet of FI engines; probably 5%. They cost less than $1000 a
set, but most pilots will spend much more for other toys, never realizing
the fuel cost savings they're missing and the damage they do to their
engines (note how many planes need a top overhaul well before TBO).

http://www.gami.com/gamijectors_order_form.html

I'll be buying an F33A in the next few weeks, and damn sure it will have
GAMI's installed before it goes anywhere.

http://www.gami.com/gamibrochure.html

(Also, I'm itching for a PRISM ignition system.)

http://www.gami.com/prism.html

HTH!!

I agree. I had GAMI's on N100DA (IO-520-B) and now TCM's (so-called)
equivalents on an IO-550 and the CHT's are way out of line.

I'm looking at getting GAMI's when the time is right.

--

Thx, {|;-)

Victor J. (Jim) Osborne, Jr.



take off my shoes to reply

Yeah, too bad they can't do something similar for carbureted engines....

"Victor J. Osborne, Jr." wrote:

I agree. I had GAMI's on N100DA (IO-520-B) and now TCM's (so-called)
equivalents on an IO-550 and the CHT's are way out of line.

I'm looking at getting GAMI's when the time is right.

--

Thx, {|;-)

Victor J. (Jim) Osborne, Jr.



take off my shoes to reply

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

"Victor J. Osborne, Jr." wrote in message
...
I agree. I had GAMI's on N100DA (IO-520-B) and now TCM's (so-called)
equivalents on an IO-550 and the CHT's are way out of line.

I'm looking at getting GAMI's when the time is right.


What time would that be?

Not only is the fuel use better, but there is virtually NO vibration since
the engine runs much more smoothly.

"O. Sami Saydjari" wrote in news:100jq2b8dks3j44
@corp.supernews.com:

Thanks for the pointers. The articles are indeed quite good, but there
is something I do not understand. It seems the whole theory on LOP
operation is conditioned on having GAMI injectors, because the article
implies that you can not do LOP operations on "normal" engines because
of uneven fuel distribution causes roughness due to different cylinders
outputing different powers when you start leaning past peak. Am I
missing something here?

Not a lot. The article is not restricted to planes with GAMIjectors, but
it *is* relevant to engines that can operate with acceptable smoothness
LOP. That rules out most every carb'd engine (although sometimes you get
lucky), and most every big-bore TCM engine. Smaller engines and Lycoming
engines are a "sometimes can and sometimes can't" proposition.

Try it at 65% power and see what happens, especially if you have all-cyl.
monitoring. [I did once have an O-320 engine that would run absolutely
smooth all the way to idle-cutoff. Just a fluke.]



-----------------------------------------------
James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
-----------------------------------------------

James M. Knox wrote:
: Not a lot. The article is not restricted to planes with GAMIjectors, but
: it *is* relevant to engines that can operate with acceptable smoothness
: LOP. That rules out most every carb'd engine (although sometimes you get
: lucky), and most every big-bore TCM engine. Smaller engines and Lycoming
: engines are a "sometimes can and sometimes can't" proposition.

: Try it at 65% power and see what happens, especially if you have all-cyl.
: monitoring. [I did once have an O-320 engine that would run absolutely
: smooth all the way to idle-cutoff. Just a fluke.]


I pretty much run my Lycoming O-360 as lean as I can get it with
at most just a slight hint of roughness. This typically amounts to
slightly lean of peak for a couple cylinders, and at peak for others.
Since Lycoming calls that "economy mode" and is acceptable for 75% power
cruise or less, I cruise at 65% max power for a margin. Watching CHT
on the hottest (#3), the spark plug probe stays at 400 or less, which is
actually more like 340 or less (on a bayonet probe). I figure that's
probably as aggressive as you can get with a normal carb'd engine. The
big thing I came away with from all the reading is if you lean
agressively, you need to know what power you're running at. Basically,
you can do anything you want with the red knob at 65% or below, provided
the CHT's are acceptable.

FWIW
-Cory

--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

I fly a lot and with a vacation in May for a few weeks. That's the right
time.

Thx, {|;-)

Victor J. (Jim) Osborne, Jr.