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

Yesterday I noticed that we had pumped more than 5000 gallons of mogas
through the Mighty Grape. This represents something like 60 complete fills
(our plane has four gas tanks, totaling 84 gallons), and around 350 hours of
flight time over the last 2.5 years.

(See: http://alexisparkinn.com/fuel_truck.htm for details on our Jim
Weir-inspired fuel truck, the "Mighty Grape"...)

At an average saving of over $1 per gallon (at the moment, it's more like
$1.25), we have paid for the truck (which we use extensively at the hotel),
the tank & pump installation (which has worked flawlessly from "Day One") --
and put aside over $2500 toward our next overhaul.

Best of all, Atlas (our Lycoming O-540-powered Cherokee Pathfinder) simply
runs best on regular, 87-octane unleaded car gasoline. In fact, the ONLY
time we've had trouble with our new engine has been when we were forced to
buy 100LL avgas, which causes lead-fouling of our spark plugs at the drop of
a hat.

All the worries that people stated, both personally and here in this forum,
have turned out to be entirely baseless. After flying with mogas for the
last 2.5 years, I can unequivocally state the following:

1. Mogas works better in my plane than avgas. Our engine runs noticeably
better on mogas.
2. I have had no problems with contamination of any kind (my pump/tank
installation has a very good filtration system)
3. If we've run across any ethanol, the engine has never burped because of
it.
4. We've run mogas from sea level to 13,500 feet, in temperatures from -15
to +97 degrees Fahrenheit, without problem.

Because of this, I state further that:

1. I would burn mogas in my plane even if it cost MORE than avgas -- it runs
that much better.
2. I will never buy a plane that doesn't have the auto gas STC.

The autogas STC is undoubtedly the best thing that has ever happened to
aircraft owners. If you've got the STC, but aren't using it, you are
literally flushing thousands of dollars down the toilet.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay Honeck wrote:
Yesterday I noticed that we had pumped more than 5000 gallons of mogas
through the Mighty Grape. This represents something like 60 complete fills
(our plane has four gas tanks, totaling 84 gallons), and around 350 hours of
flight time over the last 2.5 years.

Awww, anecdotal evidence. Statistically speaking, you need a larger
sample size

But seriously, a good post, well documented.

'Couple questions-

Do you use the same spark plugs (and same heat range) as before going
to mogas?

Do you lean, and how lean? What kind of numbers do you usually see
in different regimes of flight (EGT, CHT)? Obviously detonation
hasn't been a problem for you, I'm curious how hot you can get away
with on that engine with regular auto fuel.

Thanks.

OK, 3 questions, if you save a buck a gallon on 5000 gallons, and but
$2500 to the next overhaul, the other $2500 must buy a lot of good
beer, right?

Do you use the same spark plugs (and same heat range) as before going to
mogas?

Yep. Although because they foul too easily with 100LL (which we must buy on
long-cross-country flights), I'm probably going to go with a hotter plug
when these die.

Do you lean, and how lean? What kind of numbers do you usually see in
different regimes of flight (EGT, CHT)? Obviously detonation hasn't been
a problem for you, I'm curious how hot you can get away with on that
engine with regular auto fuel.

Sure do. At take off power, full rich, we're burning 25 gph. At cruise we
tend to run 23 squared, leaned back to 15 gph. At this setting we'll see
EGTs in the 1350 - 1450 degree range, and CHTs in the 300 - 325 degree
range.

We can, of course, throttle back to 20 squared, and burn 10 gph or less.
Danged engine is so quiet at that power setting, it's almost spooky.

OK, 3 questions, if you save a buck a gallon on 5000 gallons, and but
$2500 to the next overhaul, the other $2500 must buy a lot of good beer,
right?

Nah, beer is extra! :-)

The Grape itself cost $1800, and the tank/pump installation (and a couple of
other things) make up the other $700 or so.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay Honeck wrote:
/snip/
Sure do. At take off power, full rich, we're burning 25 gph. At cruise we
tend to run 23 squared, leaned back to 15 gph. At this setting we'll see
EGTs in the 1350 - 1450 degree range, and CHTs in the 300 - 325 degree
range.
/snip/

Jay,

Huh??? On my 230 hp O-470, I cruise at 23-squared, without any fancy
engine monitors. Using the "pull-until-it-feels-about-right" method of
leaning, I get 12 gph. Religeously. You can set your watch by that
figure. I wonder if using mogas is somehow requiring you to run 25%
richer than avgas? If so, what are your corrected savings per hour?

On a side note, as I asked you earlier, what part # spark plugs are you
running? I am curious due to your undue propensity to fouling while
running avgas.

Happy Flying!
Scott Skylane
N92054

Fat Albert the Apache dines on a diet of the cheapest, stinkiest,
crapola, 83 octane, gas I can find... He only gets toxic, lead spewing,
plug fouling, valve sticking, 100LL, on trips where I can't get to the
gas station....

My mechanic is mumbling because the plugs have gone 4 years and way
over 400 hours and are going strong... This annual he said he HAD to
change the plugs because of the hours, he felt he JUST couldn't sign
them off for another year... I said, "Fine, JUST as long as you are
paying for them!"... He changed the subject...


I lean by the EGT at 70% or higher... On local flights I am normally at
60 - 65% power, lean em until they go rough, and smile...

ymmv, sar, bni

denny

Huh??? On my 230 hp O-470, I cruise at 23-squared, without any fancy
engine monitors. Using the "pull-until-it-feels-about-right" method of
leaning, I get 12 gph.

I can lean to that fuel flow without any undue engine sounds, too. But my
EGTs go well over 1500 degrees, and my CHTs push 350 when I do.

I would rather burn a bit more gas.

On a side note, as I asked you earlier, what part # spark plugs are you
running? I am curious due to your undue propensity to fouling while
running avgas.

I have no idea, and I don't have my logs handy. However, as I said, I will
be replacing them with a hotter-burning plug when they wear out.

Of course, without all that lead fouling, they may never wear out!

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

"Jay Honeck" wrote in message
news:shJfe.64410$r53.14308@attbi_s21...
On a side note, as I asked you earlier, what part # spark plugs are you
running? I am curious due to your undue propensity to fouling while
running avgas.

I have no idea, and I don't have my logs handy. However, as I said, I
will
be replacing them with a hotter-burning plug when they wear out.

Of course, without all that lead fouling, they may never wear out!

And I've never had a fouled plug (at all...nada) in the 1400 hours I've had
my airplane, burning nothing but 100LL (TN IO-550). Maybe you're just
unlucky :~)

"Jay Honeck" writes:

Huh??? On my 230 hp O-470, I cruise at 23-squared, without any fancy
engine monitors. Using the "pull-until-it-feels-about-right" method of
leaning, I get 12 gph.

I can lean to that fuel flow without any undue engine sounds, too. But my
EGTs go well over 1500 degrees, and my CHTs push 350 when I do.
I would rather burn a bit more gas. [...]

OK, but that brings into doubt your assertion about your fueling style
being a big cost savings, doesn't it? Using 25% more fuel at 70% of
the cost per unit volume is only about a 10% savings. Or maybe you
didn't lean aggressively on avgas either?

- FChE

Jay Honeck wrote:

Huh??? On my 230 hp O-470, I cruise at 23-squared, without any fancy
engine monitors. Using the "pull-until-it-feels-about-right" method of
leaning, I get 12 gph.


I can lean to that fuel flow without any undue engine sounds, too. But my
EGTs go well over 1500 degrees, and my CHTs push 350 when I do.

EGT is irrelavant and 350 is not hot.

Jay Honeck wrote:
Sure do. At take off power, full rich, we're burning 25 gph. At cruise we
tend to run 23 squared, leaned back to 15 gph. At this setting we'll see
EGTs in the 1350 - 1450 degree range, and CHTs in the 300 - 325 degree
range.
My Comanche has an O-540 and at 22/23 I'm burning about 13 Gph with 100LL.
If there was an MOGAS STC for the Comanche I'd give it a try but that will
never happen.