MoGas Long Term Test: 5000 gallons and counting...

"Dave Stadt" wrote in message
...

"Darrel Toepfer" wrote in message
...
Morgans wrote:
"Dave Stadt" wrote

Why should I move? I can get alcohol free mogas. I taxi up and they
fill
my tanks. Price is only a couple of cents higher than the local
filling
stations.

What state, and what airport?

Louisiana - 4R7

Illinois - C77

The issue was the crapped up situation in California...though you still
might want to move :~)

Today on a long cross-country flight I experimented with the "lean-find"
function on my JPI-700 EGT/CHT meter. As always, it told me to stop leaning
when my fuel flow was right around 15 GPH. (This at 5500 feet, and 23
squared.)

Using the wisdom of the group, I kept pulling the mixture back until my
FS-450 was showing around 13 gph fuel flow, watching the EGTs and CHTs like
a hawk.

Obviously everything did run hotter, but EGTs never topped 1550 degrees, and
CHTs never topped 360 degrees. This is a tad hotter than I've been
running, but the engine sounded fine, and all cylinders stabilized within
100 degrees of each other -- which is as good as it gets on my normally
aspirated O-540.

Later, climbing to 8500 feet, we pulled it back to around 12 gph, with the
same results. (We usually would run around 14 gph at that altitude.)

So, perhaps I've been wasting gas for no good reason. Thanks to all who
responded.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

In rec.aviation.owning Jay Honeck wrote:
: Obviously everything did run hotter, but EGTs never topped 1550 degrees, and
: CHTs never topped 360 degrees. This is a tad hotter than I've been
: running, but the engine sounded fine, and all cylinders stabilized within
: 100 degrees of each other -- which is as good as it gets on my normally
: aspirated O-540.

You mean 100 EGT, right? 100 CHT would be pretty horrible, and 100 EGT is
actually pretty ragged. Just for grins, try the same power and try the two different
equalization techniques of Deakin:

- Run high enough (8500 is pretty good) so you can run WOT. Back it off about 1/4" of
MP from full throttle. Cocking the throttle plate slightly like this helps mine.
- Try the carb heat... partial to full.

I've only got analog gauges and a switch to go between them (and two less
jugs). I can say that both of those techniques get my EGT's from within 50-75 degrees
of each other to within 10-25 degrees of each other (as near as I can tell on my
tiny gauge).

YMMV... I suspect the big six on a Cherokee probably has worse fuel distro
than the four in mine.

-Cory

: Later, climbing to 8500 feet, we pulled it back to around 12 gph, with the
: same results. (We usually would run around 14 gph at that altitude.)

What percent power? Just as a datapoint, I'll get about 8.5 gph at 65-70% of
180hp. Adjusted for 6 jugs would be 12.75 gph. The compression ratio doesn't matter
for fuel flow vs. percent.

: So, perhaps I've been wasting gas for no good reason. Thanks to all who
: responded.
: --
Your plugs will be even happier. No lead *or* carbon buildup.

-Cory

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

You mean 100 EGT, right?

Yep.

- Run high enough (8500 is pretty good) so you can run WOT. Back it off
about 1/4" of
MP from full throttle. Cocking the throttle plate slightly like this
helps mine.

I discovered this technique on my own, when I found it impossible to get the
six bars on my engine analyzer to line up at full throttle. To my surprise,
pulling the MP back JUST a smidge resulted in all six bars falling neatly in
line.

YMMV... I suspect the big six on a Cherokee probably has worse fuel distro
than the four in mine.

Yeah, I've spoken with a couple of O-540 experts, and they both say that 100
degrees apart is about as good as possible with the horrible fuel
distribution of a normally aspirated Lycoming six-cylinder engine.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

In rec.aviation.owning Jay Honeck wrote:
: YMMV... I suspect the big six on a Cherokee probably has worse fuel distro
: than the four in mine.

: Yeah, I've spoken with a couple of O-540 experts, and they both say that 100
: degrees apart is about as good as possible with the horrible fuel
: distribution of a normally aspirated Lycoming six-cylinder engine.
: --

I had a friend with an O-540 that built a fuel distribution "swirler" (like
the thing on TV). Basically, a ~4x4" piece of stainless steel. Cut 10 or so
pie-shaped wedges around a carb-outlet-sided circle scribed in it. Take those
pie-shaped wedges, bend them 70-80 degrees off the plate, and give them all a 45
degree twist. Put inline between the carb and bottom of the oil pan/intake. It got
his cylinders closer together in EGT. Of course doing such modifications on anything
other than an experimental engine/airframe would immediately cause it to crash, be
illegal, immoral, reckless, dangerous, irresponsible, as well as cause global
warming, world hunger, and eventually make the sun burn out.

-Cory


--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

But it was cheap gas, right? )


Trip

In article m1She.81588$NU4.17695@attbi_s22, says...

Today on a long cross-country flight I experimented with the "lean-find"
function on my JPI-700 EGT/CHT meter. As always, it told me to stop leaning
when my fuel flow was right around 15 GPH. (This at 5500 feet, and 23
squared.)

Using the wisdom of the group, I kept pulling the mixture back until my
FS-450 was showing around 13 gph fuel flow, watching the EGTs and CHTs like
a hawk.

Obviously everything did run hotter, but EGTs never topped 1550 degrees, and
CHTs never topped 360 degrees. This is a tad hotter than I've been
running, but the engine sounded fine, and all cylinders stabilized within
100 degrees of each other -- which is as good as it gets on my normally
aspirated O-540.

Later, climbing to 8500 feet, we pulled it back to around 12 gph, with the
same results. (We usually would run around 14 gph at that altitude.)

So, perhaps I've been wasting gas for no good reason. Thanks to all who
responded.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On Mon, 16 May 2005 00:44:02 GMT, "Jay Honeck"
wrote:

Obviously everything did run hotter, but EGTs never topped 1550 degrees, and
CHTs never topped 360 degrees. This is a tad hotter than I've been
running, but the engine sounded fine, and all cylinders stabilized within
100 degrees of each other -- which is as good as it gets on my normally
aspirated O-540.

When you think about it for a minute Jay, it makes sense that the
cylinderheads cannot overheat when running lean of peak: There isn't
enough fuel in the mixture to overheat them.

Running LOP has it's consequences (less power developed), but
overheating and detonation aren't a worry.

Have you read Deakin's "Mixture Magic" column? It's EXTREMELY
comprehensive.

Corky Scott

When you think about it for a minute Jay, it makes sense that the
cylinderheads cannot overheat when running lean of peak: There isn't
enough fuel in the mixture to overheat them.

???

I can easily get my EGTs over 1600 degrees, and my CHTs near (or over) 400
degrees by over-leaning. At some temperature (and I don't know what it is)
doesn't aluminum start to weaken?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

In rec.aviation.owning Jay Honeck wrote:
: I can easily get my EGTs over 1600 degrees, and my CHTs near (or over) 400
: degrees by over-leaning. At some temperature (and I don't know what it is)
: doesn't aluminum start to weaken?
: --

Yeah... about 250-300 degrees. Comforting, no?

Remember that EGTs are useful for *relative* measurements... not absolute.
What one engine/airframe/power setting combination produces for EGTs has very little
to do with another engine/airfram/power setting EGT. It's best used to find the peak,
and to see how even individual cylinders are by dithering around the peaks. Saying
one is at 1550 and another is at 1590 doesn't mean much... one may have a slightly
different position in the EG stream, more resistance inthe probe wiring, etc, etc...
run the mixture above and below to see where *each* peaks (below 75% of course).

Again... absolute EGT number is nothing to be concerned about (within reason,
but it's generally impossible to exceed reason with a certified engine). The EGT is
much more important, and running at or below 400 in cruise is considered acceptable.

-Cory


--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

wrote:

The EGT is
much more important, and running at or below 400 in cruise is considered acceptable.

I'm sure you meant "CHT" in that sentence.

George Patterson
"Naked" means you ain't got no clothes on; "nekkid" means you ain't got
no clothes on - and are up to somethin'.