MoGas Tips, Tricks, Concerns, How To

If you'd just get the operation, you and Mary wouldn't have to USE
conundrums.

Jim



Golly, what a conundrum...

Switching to courtroom mode

"So, Teledyne Director Of Engineering, would you please tell the court why
you recommended exceessive leaning and poor quality automobile fuel when we
have sworn testimony that it was this lethal combination that caused this
poor widow and her children to lose a husband and father?"

It sure as hell wasn't for engineering reasons that they made these
pronouncements.

mode off

Jim



Teledyne Continental and (I think) Lycoming have both gone on record
to say that mogas is damaging to their engines. They are certainly
multi-millon dollar aircraft engine companies and have have no
incentive to lie to you.

They are also multi-million dollar aircraft engine companies that
recommend against LOP operation. (Unless you are running a FADEC system).

Allen

On Sat, 13 May 2006 16:15:01 GMT, wrote:

.Blueskies. wrote:

"Bela P. Havasreti" wrote in message ...
On 12 May 2006 12:00:24 -0700, "M" wrote:

Lower octane autogas is quite common in mountain states where the
elevation is high. Non turbo-charged car engines have a bigger
denotation margin at higher elevation and require less octane.

So that's why "super" mogas in Florida is 93 octane but only
92 octane in the Seattle area. Thanks everyone for the replies
(usenet is good for something besides arguing about politics
afterall!).

Bela P. Havasreti


Both Seattle and Florida are basically at sea level. The lower octane is not explained by altitude difference in this
case....

Most of Florida is close to sea level.

You don't have to go far from downtown Seattle to be at 6000 feet.

True. I live at 466 feet (Crest Airpark / S36). I can be at 3000
feet (in my car) within a 25-30 minute drive.

Bela P. Havasreti

"RST Engineering" wrote in message .. .
Uhhh, no it didn't. It was allowed a MAXIMUM of 0.5 ml / gallon of TEL, but from the '50s on, the actual TEL count
was zero in 80.

Jim


Thanks Jim. That's the first I had heard that...but it was not declared as no-lead fuel, so the post asking for what was
the favorite unleaded fuel was a loaded question, eh?

wrote:

: Most of Florida is close to sea level.

I think the highest elevation in Florida is 120-ish feet? I think that's
what the sectional shows.

--
Aaron C.

Jay Honeck wrote:

: A touch of Carb heat and the throttle cracked ever so slightly. It creates
: turbulence in the intake system that evens things out rather nicely.

: Care to expand on that?

Boy, I'm ever so worried to jump into a religious shouting match. But...

When I flew the Cherokee 180, carb'd O-360 or course, I could run LOP with
carb heat turned up. I could use the mix to slow the engine down until
it wasn't producing any useful power. It ran smoothly during this. Without
carb heat it would let you know if you went too far LOP.
I can't repeat these experiments; I'm sure the guy who owns my plane now
would be upset!
--
Aaron C.

Here's another tip for carbureted engines only. When operating at full
throttle, it is often helpful to back off on the throttle until you see just
the tiniest drop in MP (if you have a MP gauge, otherwise look for the
slightest drop in RPM), and leave it there instead of fully open. That cocks
the throttle plate just enough to set up a slightly turbulent flow, and that
helps mix the fuel and air for better combustion. A touch of carburetor heat
may help, too.

Using our JPI EDM700 engine analyzer as our guide, we usually can get
all 6 cylinders within 70 degrees of one another using the "pull the
throttle back a hair" method at altitudes from 4500 to 8500 feet.

At full throttle, we're lucky to get them within 150 degrees of
matched.

Never tried the carb heat thing. We don't have a carb temperature
gauge.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

"Aaron Coolidge" wrote in message
...
Jay Honeck wrote:

: A touch of Carb heat and the throttle cracked ever so slightly. It
creates
: turbulence in the intake system that evens things out rather nicely.

: Care to expand on that?

Boy, I'm ever so worried to jump into a religious shouting match. But...

Is it "religious", or religion [anecdote (my mechanc says...,the
manufacturers say without supporting evidence], blind faith [redundant]) vs
science (graphs, charts test stand data)?

A couple of points:

1) My copy of ASTM spec D910 page 0539 states that the allowable TEL
content of 100LL avgas is 2 milliliters per gallon NOT 2 grams per
gallon. This means there will be over 1/3rd pound of lead in an 80
gallon tank of 100LL, plus about 1/5th pound of ethlylene dibromide
scavenging agent.

2) My muffler "failures" were from the internal flame tubes, which
must be present and in reasonable condition if they were originally
present when new, but are not required on later mufflers that did not
have the internal flame tubes. We did a proctoscope exam with a small
flashlight at annual to verify their condition. Our engine was run
about 50 deg rich of peak, or so we thought as we had only a single EGT
probe. There was little engine roughness though if the mixture was
leaned further. Manifold pressure was set to 21 inches for cruise,
less at higher altitudes.

I suspect many 172s were just run until the flame tubes were all gone
out the tailpipe.

"nrp" wrote in message
oups.com...
A couple of points:

1) My copy of ASTM spec D910 page 0539 states that the allowable TEL
content of 100LL avgas is 2 milliliters per gallon NOT 2 grams per
gallon. This means there will be over 1/3rd pound of lead in an 80
gallon tank of 100LL, plus about 1/5th pound of ethlylene dibromide
scavenging agent.

Aside from the curiousity of mixing gallons and metric measurments, 2
gr/gallon is 160 grams in an 80 gallon tank. 160/454=0.3524 lbs, so it's
virtually the same thing. SAW, 160 gr in a tank that holds 36,320 grams, 1/3
lb in a tank holding 480 lbs.