MoGas Tips, Tricks, Concerns, How To

It seemed as though the AOPA article ignored the proven success of
MoGas, but it did point out the very limited success of 100LL
alternatives. I wonder if there are any more high compression engines
running in test cells trying replacement fuels. It sounded like there
was only one.

nrp wrote:
It seemed as though the AOPA article ignored the proven success of
MoGas, but it did point out the very limited success of 100LL
alternatives. I wonder if there are any more high compression engines
running in test cells trying replacement fuels. It sounded like there
was only one.

What is the proven success of Mogas? I mean, besides testimonials
from its users on this newsgroup, what proof is there of Mogas success,
and how would it be defined?

For example in their article on fuel, Aviation Consumer had a sidebar
on mogas saying it wasn't as good as advertised. They said several
shop owners told them that when they get engines or cylinders in for
work, they can immediately tell if the owner is running mogas by the
corroded camshafts and deposits on the valves and seats. These shop
owners claimed that the extra overhaul costs eliminate the mogas
savings, and attribute it to the "varying additives" used in mogas and
to the fact that most mogas sold doens't really meet the ASTM standards
dictated by the STC.

Personally I don't know, I have no experience with Mogas, all I have to
go on is what I read here and in other sources. It would be a pity if
this was correct, especially with rising 100LL prices.

I remember traveling in 1974 with a British engine engineering
consultant who was absolutely positive the US auto manufacturers were
going to be in for a rude surprise when unleaded fuels were foist upon
them by the EPA and the 1975 catalytic converter needs. He predicted
valves and seats would quickly fail creating a massive maintenance
problem.

It never happened. Hardened valve seats were used from the beginning,
and the reduction in engine contamination has given us longer service
intervals and incredibly long lived automotive engines today.

Where are the hardened seats for aircraft engines? Even something that
recognizes some fuels don't have TEL in them? I've lived with over 20
years of autofuel in my O-320-E2D (one of the first STCs from Petersen)
using low cruise powers, hoping to minimize valve seat recession. So
far I've been very successful.

The lack of a consistent airport distribution system to assure quality
for MoGas after 20 years is crazy. There must be other forces at work
that are not obvious to me.

I did not think the AOPA article ignored mogas. It is a solution for some
people, but not a solution for the market as a whole. You can't replace
100LL with mogas when 30% of the planes ( and 70% of the consumption ) can't
use it. You could offer it in parallel with the 100LL, but that would
require the small airports to pay for twice the deliveries, and have twice
the pumping equipment. The airports would also have to figure out how to
ensure the supply is not contaminated. Normal mogas delivery system is not
used to keeping things to a life critical quality. There would also have to
be changes in the tax code so that aviation taxes could be levied on the
mogas. The revenuers job would get harder because they would have to make
sure small airports didn't fill there tanks with mogas at the automobile tax
rate. It is only fair that the mogas aviators pay their share of the FAA and
ATC burden.

I am not saying the infrastructure could not be changed to use mogas, but it
would take the effort of the entire aviation community and the federal
government. There is a lot of inertia to overcome to save a few bucks.

I also agree with posters that claim that mogas can lead to early engine
wear. The fuels may be equivalent under normal circumstances, but if the
engine overheats, the low octane fuel will do a lot more damage than the
high octane fuel.

"nrp" wrote in message
oups.com...
I remember traveling in 1974 with a British engine engineering
consultant who was absolutely positive the US auto manufacturers were
going to be in for a rude surprise when unleaded fuels were foist upon
them by the EPA and the 1975 catalytic converter needs. He predicted
valves and seats would quickly fail creating a massive maintenance
problem.

It never happened. Hardened valve seats were used from the beginning,
and the reduction in engine contamination has given us longer service
intervals and incredibly long lived automotive engines today.

Where are the hardened seats for aircraft engines? Even something that
recognizes some fuels don't have TEL in them? I've lived with over 20
years of autofuel in my O-320-E2D (one of the first STCs from Petersen)
using low cruise powers, hoping to minimize valve seat recession. So
far I've been very successful.

The lack of a consistent airport distribution system to assure quality
for MoGas after 20 years is crazy. There must be other forces at work
that are not obvious to me.

I also agree with posters that claim that mogas can lead to early engine
wear. The fuels may be equivalent under normal circumstances, but if the
engine overheats, the low octane fuel will do a lot more damage than the
high octane fuel.

That is simply not true. Perpetuating a myth like that in this forum
is not productive.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

1 The octane measurement is an attempt to quantify a fuels propensity for
detonation or pre combustion. Higher octane means less propensity.
2 Precombustion and detonation are usually caused by, among other things,
engine overheating, and hot spots.
3 Precombustion and detonation can lead to further increases in CHT.
4 Precombustion and detonation can damage an engine.
5 High CHTs can damage an engine.

Let me know which of the above statements you disagree with, and I will find
a reference for it.
I stand by my statement that an overheated engine will be more damaged if it
is running lower octane fuel.

"Jay Honeck" wrote in message
oups.com...
I also agree with posters that claim that mogas can lead to early engine
wear. The fuels may be equivalent under normal circumstances, but if the
engine overheats, the low octane fuel will do a lot more damage than the
high octane fuel.

That is simply not true. Perpetuating a myth like that in this forum
is not productive.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Let me know which of the above statements you disagree with, and I will find
a reference for it.
I stand by my statement that an overheated engine will be more damaged if it
is running lower octane fuel.

None of your statements are incorrect, they are merely irrelevant.

Low-compression aircraft engines were designed to run on 80 octane
fuel. Running fuel of higher octane is not going to hurt anything --
but it won't help, either.

87 octane auto gas is perfect for our low compression engines, and
certainly won't hurt them. Using "premium" (or, for that matter, 100
LL) is neither necessary nor recommended.

(Note: SOME mogas STCs do require using a higher octane car gas, but
those are the exception, not the rule.)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

For example in their article on fuel, Aviation Consumer had a sidebar
on mogas saying it wasn't as good as advertised. They said several
shop owners told them that when they get engines or cylinders in for
work, they can immediately tell if the owner is running mogas by the
corroded camshafts and deposits on the valves and seats. These shop
owners claimed that the extra overhaul costs eliminate the mogas
savings, and attribute it to the "varying additives" used in mogas and
to the fact that most mogas sold doens't really meet the ASTM standards
dictated by the STC.

I read that article, and it is the closest thing to total bull**** I've
ever read on the subject. I can line up several shop owners who will
absolutely contradict the statements of those supposed "shop owners".


Nearly every INDEPENDENT shop owner I know (and that distinction seems
to be critical here) will testify that engines that have ran on
unleaded fuels are MUCH cleaner inside. They will tell you that they
can tell instantly upon teardown whether someone has been burning 100
LL in an engine that was designed to run on 80 octane avgas, simply by
the amount of crud inside.

100 LL has FOUR TIMES the amount of lead that my engine was designed to
run with. As a result, spark plugs foul with lead far easier, making
it necessary to aggressively lean the engine. Which, of course, in
turn leads to much higher exhaust gas temperatures, and unnecessary
wear and tear on the engine.

The ONLY time I've ever had engine trouble with Atlas' O-540 was on a
road trip where I was forced to run exclusively 100LL for days on end.
I fouled a cylinder so badly that BOTH spark plugs ceased firing,
requiring a quick return to the airport landing, (Not QUITE an
emergency, but close...)

I would run 87 octane unleaded car gas in my engine if it cost MORE
than 100LL. My engine simply runs better and cleaner on it, and I will
not run 100 LL unless I am forced to use it.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Have to agree with you Jay. I've had both my engines apart before and
after running Mogas for some time and both were much cleaner after
Mogas. Simply far less combustion chamber deposits, cleaner valves with
no measurable valve seat change. I notice no difference in the way my
0-360 Lyc runs but a big improvement in the way my 0-300D Cont runs.
One can forget about it until going cross country where no Mogas is
available and it starts running finaky again.
I figure if I'm too weak to lift a 5 gallon container of gas up onto
the wing then I'm too weak to fly and better get another pass time (or
let my wife do it. after all its her plane).
Jim

Jay Honeck wrote:
For example in their article on fuel, Aviation Consumer had a sidebar
on mogas saying it wasn't as good as advertised. They said several
shop owners told them that when they get engines or cylinders in for
work, they can immediately tell if the owner is running mogas by the
corroded camshafts and deposits on the valves and seats. These shop
owners claimed that the extra overhaul costs eliminate the mogas
savings, and attribute it to the "varying additives" used in mogas and
to the fact that most mogas sold doens't really meet the ASTM standards
dictated by the STC.

I read that article, and it is the closest thing to total bull**** I've
ever read on the subject. I can line up several shop owners who will
absolutely contradict the statements of those supposed "shop owners".


Nearly every INDEPENDENT shop owner I know (and that distinction seems
to be critical here) will testify that engines that have ran on
unleaded fuels are MUCH cleaner inside. They will tell you that they
can tell instantly upon teardown whether someone has been burning 100
LL in an engine that was designed to run on 80 octane avgas, simply by
the amount of crud inside.

100 LL has FOUR TIMES the amount of lead that my engine was designed to
run with. As a result, spark plugs foul with lead far easier, making
it necessary to aggressively lean the engine. Which, of course, in
turn leads to much higher exhaust gas temperatures, and unnecessary
wear and tear on the engine.

The ONLY time I've ever had engine trouble with Atlas' O-540 was on a
road trip where I was forced to run exclusively 100LL for days on end.
I fouled a cylinder so badly that BOTH spark plugs ceased firing,
requiring a quick return to the airport landing, (Not QUITE an
emergency, but close...)

I would run 87 octane unleaded car gas in my engine if it cost MORE
than 100LL. My engine simply runs better and cleaner on it, and I will
not run 100 LL unless I am forced to use it.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

"Jay Honeck" wrote in message
oups.com...
For example in their article on fuel, Aviation Consumer had a sidebar
on mogas saying it wasn't as good as advertised. They said several
shop owners told them that when they get engines or cylinders in for
work, they can immediately tell if the owner is running mogas by the
corroded camshafts and deposits on the valves and seats. These shop
owners claimed that the extra overhaul costs eliminate the mogas
savings, and attribute it to the "varying additives" used in mogas and
to the fact that most mogas sold doens't really meet the ASTM standards
dictated by the STC.

I read that article, and it is the closest thing to total bull**** I've
ever read on the subject. I can line up several shop owners who will
absolutely contradict the statements of those supposed "shop owners".


100 LL has FOUR TIMES the amount of lead that my engine was designed to
run with. As a result, spark plugs foul with lead far easier, making
it necessary to aggressively lean the engine. Which, of course, in
turn leads to much higher exhaust gas temperatures, and unnecessary
wear and tear on the engine.

Now that's bull****. Aggressive leaning is COOLER when done properly (i.e.,
using the proper temp range when LOP. It also produces lower internal
cylinder pressures, more through combustion, lower CHT temps.