Fuels- everything you didn’t need to know
Since the very beginning of time, mankind has
been on the quest for FUEL, probably, indisputably the number one
invention of all time. Our use of fuel started in prehistoric times
as a way to heat our cave and then to cook our food, then to power
our motorcycles (sorry cavemen!)
Without Fuels to produce heat, we wouldn’t have any metal, so we
would still be in the Stone Age. Without Fuel NONE of today’s modern
age society would exist as we know it. We use Fuels for so many
things that if you took a few minutes to think about it you would
realize that we couldn’t live without them. Take that you greenie
hypocrites!
Gasoline was not invented; it is a natural by-product of the
petroleum industry, kerosene being the principal product. Gasoline
is produced by distillation, the separating of the volatile, more
valuable fractions of crude petroleum. However, what was invented
were the numerous processes and agents needed to improve the quality
of gasoline making it a better more stable fuel.
One thing virtually every fuel has in common is that by itself, it
is not combustible- they require an Oxidizer. The most easily
obtained oxidizer we have available to us is our AIR and it’s oxygen
component. Internal Combustion engines mix fuel and air enabling the
combustion process. With a spark at the right time we are able to
make power.
Now, the real reason for this article- to discuss motor fuels and
their effect on our Yamaha Engines. Probably the number one question
I get asked is- “What type of motor fuel is best in my motorcycle?”
Well let’s first look at the Components of today’s modern fuels.
Today’s Fuels are filled with lots of stuff, but they all start with
a base petroleum distillate, and then other things are added. Some
compounds added are Detergents (to help keep the combustion tracts
clean) and oxygenates (which are supposed to reduce some of the
harmful compounds emitted by the combustion process). These
additives have an overall effect on the one thing we are all most
concerned about- the Octane rating.
The Octane rating of a gasoline is a measurement of the burn rate of
the fuel. In internal combustion engines, the compressed
gasoline-air mixtures have a tendency to ignite prematurely rather
than burning smoothly. This creates engine pre- ignition or knock, a
characteristic rattling or pinging sound in one or more cylinders.
The octane number of gasoline is a measure of its resistance to
knock. The octane number is determined by comparing the
characteristics of a gasoline to isooctane (2,2,4-trimethylpentane)
and heptanes. Isooctane is assigned an octane number of 100. It is a
highly branched compound that burns smoothly, with little knock. On
the other hand, heptane is given an octane rating of zero. It is an
unbranched compound and knocks badly. By averaging the burn rate of
a particular fuel, we can determine its octane rating. The one
missing link is the consistency of a particular fuels quality to
maintain this rating. Lot’s of stuff affects a fuels quality, but
nothing as much as the current trend of OXYGENATES added to fuel.
The most common Oxygenate used today is Alcohol, and this really
messes with fuel quality as the alcohol being used absorbs water
from the air and we all know gas and water don’t like each other…
It is important to note that the theoretical energy content of
gasoline when burned in air is only related to the hydrogen and
carbon contents. Octane rating is not fundamentally related to the
energy content, and the actual hydrocarbon and oxygenate components
used in the gasoline will determine both the energy release and the
anti-knock rating. This is the main reason Racing Gas does not provide more power in a stock
engine.
Can I run racing gas in my bike? Yes, you could run unleaded racing
gas, but it is a waste of money. You will not make more power nor
will you get better mileage- actually probably worse mileage.
Why is
Racing Gas so expensive? Because it is a more highly refined fuel.
This makes the fuel more stable and resistant to pre-ignition. The
Stability is important when we ask a highly tuned engine to run “on
the edge” because even a small pre- ignition event can destroy a lot
of parts. One way we test our racing gas is with a hydrometer. We
measure the fuels specific gravity. This is a measurement of the
density of the fuel. Racing gasolines are typically denser than pump
gas. When run through a carbureted engine set up for pump gas, the
racing gas will typically be too rich for the pump gas jetting.
When gasoline is left for a period of time, gums and varnishes may
build up and precipitate in the gasoline, causing "stale fuel". This
will cause gums to build up in the fuel tank, lines, and carburetor
or fuel injection components making it harder to start the engine.
Motor gasoline may be stored up to 60 days in an approved container.
If it is to be stored for a longer period of time, a fuel stabilizer
may be used. This will extend the life of the fuel to about 1–2
years, and keep it fresh for the next uses. Fuel stabilizer is
commonly used for small engines such as lawnmower and tractor
engines to promote quicker and more reliable starting. We recommend
that you keep gasoline containers and tanks more than half full and
properly capped to reduce air exposure, to avoid storage at high
temperatures, to run an engine for ten minutes to circulate the
stabilizer through all components prior to storage, and to run the
engine at intervals to purge stale fuel from the carburetor.
What about “Avgas” or Aviation Gasoline? What about it- it is MADE
FOR AIRPLANES. Avgas has a lower and more uniform vapor pressure
than automotive gasoline, which keeps it in the liquid state at
high-altitude, preventing vapor lock. The particular mixtures in use
today are the same as when they were first developed in the 1950s
and 1960s, and therefore the high-octane ratings are achieved by the
addition of tetra-ethyl lead (TEL), a highly toxic substance that
was phased out for car and motorcycle use in most countries in the
late 20th century. Don’t run it in your bike. First, you don’t need
to, second the lead will kill your catalytic converter.
So, what should you do for your Yamaha engine?
1. Run the highest pump octane number available (usually 92) more
octane is not necessary, but less is bad.
2. Run a name brand fuel- preferably from the same station
3. Don’t use Octane Boosters or other “Power Additives”
4. Don’t let your bike sit for more than 60 days without putting
some
Yamaha Fuel Conditioner and Stabilizer in the fuel system
Happy Riding!
Dr Jay
What About E-10 Fuels? - Fuels Continued