Autogas Tips and Tricks

"Orval Fairbairn" wrote in message
news
In article ,
"Blueskies" wrote:

"john smith" wrote in message
...
In article . com,
Jay Honeck wrote:

Sorry Dan, but I can't let this lay. You are spreading dangerous and
misleading misinformation.


Jay, just because your engine works well with it does not mean others
will. There are many variables. That is why there is an STC for each
aircraft/engine combination.

Exactly right, and if Cubdriver used autogas with a STC then it should work
as published, no issues with operation.
However, if there is not an STC then all bets are off. I would be surprised
if there was not a STC for the old Cubs
however....

The old Cubs were designed to run on WW-II "combat gas," which was the
mogas issued to run Jeeps, trucks, tanks, etc.

The STC equipment for the Cub is a clip fastened to a pushrod housing
and a note on the gas cap.

Thanks!
And that means that all testing has been done using 87 "octane" mogas and the engine operated completely normally with
no new or additional operating limitations.

Cubdriver said "More serious for me, sitting in the back seat, was that the engine was prone to quit. The worst moment
was flaring on landing, when the airstream stopped driving the prop, the prop stopped driving the engine, and the engine
stopped. Most pilots claim that the engine runs better on mogas, but this was not my experience." This issue is likely a
mis-adjusted engine mixture or a bad carb than an issue with mogas usage...

On 1 May, 04:25, Orval Fairbairn wrote:
In article ,





"Blueskies" wrote:
"john smith" wrote in message
.. .
In article . com,
Jay Honeck wrote:

Sorry Dan, but I can't let this lay. You are spreading dangerous and
misleading misinformation.

Jay, just because your engine works well with it does not mean others
will. There are many variables. That is why there is an STC for each
aircraft/engine combination.

Exactly right, and if Cubdriver used autogas with a STC then it should work
as published, no issues with operation.
However, if there is not an STC then all bets are off. I would be surprised
if there was not a STC for the old Cubs
however....

The old Cubs were designed to run on WW-II "combat gas," which was the
mogas issued to run Jeeps, trucks, tanks, etc.

Well, not exaclty, the A65 and it's predecessors were designed before
WW2 and in any case weren't designed for the military market, but
there wasn't much difference in Avgas and autogas at the time anyway.
The Cont. A-40, 50 and 65 were all designed with a min octane rating
of 73, which required no lead whatsoever to achieve. Their compression
ratio is sop low they don't get hot enough for the various ingredients
of higher lead fuels to digest the mix properly, resulting in deposits
on the plugs and valve stems gumming up the works anyway. 100LL has a
considerable amount of lead in it still (about 4X the amount 80/87
has) and these engines don't like it one little bit.
Of course, you can always dump a little Marvel Mystery oil in there,
which not only lubes the top end, it helps burn off deposits...
MY old Le Blond is rated for 60 Octane fuel! I'm checking into the
viability of running it on carrot juice..


Bertie

The OP asked about using MoGas & this has turned into a discussion
dissing Ethanol laced fuels (which should be dissed).

But if you get a candidate auto gasoline, it can be easily tested to
make sure it isn't adulterated by ethanol. Mix 1 part of water with
about 10 parts of sample gasoline in a test tube, shake for a couple
of minutes, and see if the apparent water level has increased. If
not, it does not contain alcohol.

Trying to remove alcohol with water is suicidal. The resulting octane
number is lowered creating the possibility of a detonation related
engine failure.

If your state has mandated ethanol for autos, look for an alternate
source such as marinas or other specialty pumps. One problem with
E-10 fuels is an engine will only deliver about 95% of full horsepower
on the stuff. There is a long term hose compatibility problem &
possibly the accelerator pump & needle-and-seat in the carb bowl will
give trouble. The needle tip may not be compatible, and if it sticks,
you might have an engine failure. Your float should already have been
changed back to metal if all the carb ADs have been complied with.
Your tanks are metal too. There are elastomeric seals in your fuel
selector and primer, but I got 20 years of autofuel use out of my 172M
without seal service or any other difficulty.

Some will argue the vapor pressure of autofuel is higher (yes it
generally is). But you don't have a fuel pump and your gravity-based
Cessna fuel system is quite resistant to vapor lock. Your 172's
brothers have a rare fuel delivery problem that is mystery-based &
that's why the placard for single tank above 5000 ft msl has been
added. This problem was encountered back in the days of never-use-
autofuel-or-you-will-crash.

Actually the vapor pressure difference between autofuel and AvGas is
alternatively eaten up by only about a 15 degreeF fuel temperature
difference. Where is the rule saying you can't paint your wings black
(vs cooler white)? Fuel delivery systems that are marginal on
autofuel will usually be marginal on AvGas too.

Starting will be a little different - particularily if your aircraft
has been sitting for weeks. On shutdown, I first shut off the fuel &
run the carb bowl empty if the plane is going to sit more than a
couple of weeks. It does make restart simpler.

Occasional use of 100LL might help the exhaust valves - or it may be
an old wives tale. Many do say breakins of a new or fresh majored
engine should involve some leaded fuel.

Your plugs will easily go 100+ hours without cleaning. Your oil will
not get gray from lead in the blowby.

You might want to install an EGT as it seemed to me that my engine ran
slightly leaner with autofuel. I found the fuel consumption of
autofuel is slightly less. I think it weighs very slightly more per
gallon.

Autofuel does not cause warts or hemorrhoids (sp?).

On 29 Apr 2007 20:47:01 -0700, Jay Honeck wrote:

If your engine was quitting on final, I would have some serious
maintenance done on your Cub -- *or* I'd carefully check the quality
of your fue

Sorry, but that's the way it happened, and as a result (plus the fact
that the instructors didn't like the smell) that the airport yanked
the STCs on its Cubs. They have operated on 100LL for the past two
years, with none of the quitting problems that afflicted them in cold
weather during the mogas era.

I appreciate that the experience is politically incorrect, and I knew
it would upset people. But it wasn't my experience, and it wasn't my
Cub; I was only a renter. Scores of other pilots flew the Cubs with
mogas and had the experience of engines quitting in cold weather. He
restarted it by diving at the beach.) For this airport, and its two
rental Cubs, mogas was a bad experience.

The airport still sells mogas. I buy it for all my small engines,
since this part of the state went to ethanol-diluted gasoline last
fall.

Say it ain't so, if you like. But it was so.

Blue skies! -- Dan Ford

Cubdriver wrote:
On 29 Apr 2007 20:47:01 -0700, Jay Honeck wrote:

If your engine was quitting on final, I would have some serious
maintenance done on your Cub -- *or* I'd carefully check the quality
of your fue

Sorry, but that's the way it happened, and as a result (plus the fact
that the instructors didn't like the smell) that the airport yanked
the STCs on its Cubs. They have operated on 100LL for the past two
years, with none of the quitting problems that afflicted them in cold
weather during the mogas era.

I appreciate that the experience is politically incorrect, and I knew
it would upset people. But it wasn't my experience, and it wasn't my
Cub; I was only a renter. Scores of other pilots flew the Cubs with
mogas and had the experience of engines quitting in cold weather. He
restarted it by diving at the beach.) For this airport, and its two
rental Cubs, mogas was a bad experience.

The airport still sells mogas. I buy it for all my small engines,
since this part of the state went to ethanol-diluted gasoline last
fall.

Say it ain't so, if you like. But it was so.

Blue skies! -- Dan Ford

Were the buying the mogas in small quantities frequently or in a large
tank infrequently? It is quite well-known that mogas has a summer blend
and a winter blend (or blends in some areas). The winter blend has a
higher RVP. If you burn summer auto fuel in cold weather, you are
asking for trouble. I ran mogas in my Skylane for 6 years in fairly
cold northern PA winters and never had a "quiting" problem. I had only
a 50 gallon tank so I typically bought the fuel on the way to the
airport so it was always both fresh and in season.

Matt

If you got gasoline in season and you bred it, could you get litters of
gasopuppies?

Jim


"Matt Whiting" wrote in message
...


I had only
a 50 gallon tank so I typically bought the fuel on the way to the airport
so it was always both fresh and in season.

Matt

RST Engineering wrote:
If you got gasoline in season and you bred it, could you get litters of
gasopuppies?

No, you would get liters. :-)

Matt