REASONS BEHIND THE ANSWERS
Last month in The Racer’s
Edge column we presented a quiz on Racing Fuels. The answers to the questions
were all “False”, and a number of readers asked that we provide explanations.
The author, H. David Redszus of Precision Automotive Research, Bensenville,
Illinois provides detailed answers to the questions.
1. A racing fuel makes
more power because it has higher octane?
FALSE: A racing fuel
does not make more power merely because it has a higher octane number.
Higher octane does not allow the engine builder to make mechanical modifications
which produce more power without engine destruction. A racing fuel with
a higher octane number than another, but with no other changes in the fuel,
would make the same power.
2. Too much octane could
be bad for an engine?
FALSE: Too much octane
alone can never hurt an engine, but could be bad for your checkbook and
racing budget. Other changes in fuel composition not related to octane
can, however, have either a beneficial or detrimental effect on your engine.
3. All racing fuels are
the same if they have the same octane?
FALSE: The octane number
is only one of about a dozen important characteristics of a good racing
fuel. Other important considerations are: cooling effects, ignitability,
flame speed, carbon/hydrogen ratio, evaporation rate, deposits, consistency
and many more.
4. Low performance stock
engines rarely benefit from using racing fuel?
FALSE: When properly
matched to the needs of a specific engine, a quality racing fuel can eliminate
misfires and malfires, improve cleanliness, improve throttle response,
increase volumetric efficiency and avoid torque curve flat spots.
5. Race fuel should be
always stored in a tightly sealed red plastic container designed for the
purpose?
FALSE: Red (or any other
color) plastic containers are only good for lawn mower fuel. They may be
used to mix oil/fuel and to transfer fuel providing the fuel does not remain
in the plastic container for more than a few (one maybe?) hours. Plastic
containers, which permit the passage of ultraviolet rays (sunlight), can
destroy the octane value of leaded fuel in as little as 20 minutes. All
plastic containers except Teflon and Nylon allow the migration of light
fuel infractions right through the porous plastic container walls. Always
store your race fuel in steel cans away from heat and light.
6. Race fuels may be safely
purchased in bulk provided it comes from underground tanks?
FALSE: Large 500-2500
gallon underground storage tanks permit the exposure of race fuel to air
in the tank space as the tank is emptied. This allows the evaporation losses
of fuel light ends which are essential components of a superior race fuel.
Tanks must be vented to the air which exposes the fuel to moisture which
condenses and sinks to the bottom. The water-to-fuel interface is a perfect
area for black slime microbial growth which feed on hydrocarbons. When
a large tank is freshly filled, the bottom residing contaminants are agitated
and may end up in your engine. Always filter race fuel using a very fine
filter (25 microns) and use a fresh, clean fuel filter (10 microns) on
your engine.
7. Nitrous oxide makes
about 30% more power than gasoline?
FALSE: Nitrous oxide
is an oxygenate, not a fuel, and does not make power. It adds substantial
oxygen to the combustion process which must be balanced by an increase
in fuel volume to avoid an excessively lean condition (and engine destruction)
and to obtain a performance increase. When using nitrous oxide always use
the highest available octane and run on the slightly rich side to be safe.
Spark plugs should be replaced with much colder plugs to avoid pre-ignition.
Nitrous oxide and low quality race fuel have eaten many, many race engines
and racers have paid dearly.
8. Racing fuel is toxic
and dangerous to handle?
FALSE, sort of: Actually,
this is a badly worded question for which I apologize. I meant to say,
“…as compared to ordinary pump gas…”. Premium quality racing gas is actually
more pure and less harmful than ordinary pump gas. But, ALL gasolines are
toxic by their very nature and should be handled with care and plenty of
respect. Transfer fuel only in a well ventilated area and do not breathe
the fumes. Keep away from children and pets. Store in a tightly sealed
steel container in a cool, well-ventilated space. Never permit smoking
anywhere near a refueling operation since race fuels are quite volatile
and vapors can be easily ignited. Don’t wash your hands or parts in gasoline.
Do wash your hands every time you handle fuel.
9. Racing fuel contains
more energy than pump gas?
FALSE: All hydrocarbon-based
gasolines contain about the same amount of energy: approximately 19,800
BTUs per pound of fuel, or over 120,000 BTUs per gallon. Fuel is metered
by volume but combustion processes are governed by the weight of the reactants.
When fuel is adjusted for stoichoimetery and specific gravity, all gasolines
contain about the same energy. The energy variance between fuel is usually
less than 1%.
10. Racing fuel has along
shelf life and should be purchased in economical bulk sizes?
FALSE: Premium racing
fuel is very much like fine win. If it is improperly transported or stored,
it can deteriorate very quickly and like a skunked wine, leave a bad taste
in your mouth. Never purchase in larger quantities than you can quickly
use, no matter how tempting the economies may appear. If bulk fuel purchases
can be quickly used or shared among competitor, then a bulk purchase makes
sense. A fresh, unopened steel can may be safely stored (at cool temperatures)
for up to six months. Once opened, the shelf life deteriorates rapidly.
Use it up within two weeks. Preserving the freshness of a race fuel is
difficult even for refineries, let alone racers.
11. Exhaust gas temperatures
are a good way to evaluate and select a racing fuel?
FALSE: Exhaust gas temperatures
are a very inaccurate way to determine fuel quality unless several operating
variables are understood and controlled. Generally, the higher the exhaust
temperature produced, the better. But higher exhaust temperatures could
also be the result of improper mixture, fuel preparation or ignition timing
adjustments. More horsepower and higher RPMs always result in higher exhaust
temperatures. But this can lead to engine overheating unless thermal dissipation
provisions have been made for higher performance. There is simply no substitute
for the correct matching of fuel type to engine requirements, proper fuel
and ignition tuning and careful measurement of the shape of the torque
curve on an engine dynamometer.
12. A high-octane race
gas burns slowly to prevent engine destructive detonation?
FALSE: Most destructive
detonation has its origins in improper chamber design, inadequate chamber
cooling or improper ignition timing. Gasoline flame speed is much more
dependent on squish velocity and combustion turbulence than on octane characteristics.
Higher octane does, however, raise the auto-ignition temperature at which
detonation begins.
13. A direct, back to
back comparison test of various fuel brands is the best way to select a
racing fuel?
FALSE: When different
fuels are compared to evaluate performance, the ignition, air/fuel ratio
and mixture preparation must be optimized for each fuel before comparison
can be made. Simple back to back test without optimized tuning is easy
to do but completely wrong.
14. Leaded racing gas
makes more power than unleaded racing gas?
FALSE: Leaded racing
gas makes the same power as unleaded racing gas if all other things are
equal (i.e. octane, specific gravity, stoichoimetry, distillation curve,
fuel composition, etc.). Unfortunately, all other things are almost never
equal. Racing fuel, unlike pump gas, is sold with detailed product specifications.
Understanding fuel specifications and their proper application will put
you a lap ahead of the filed.
15. You can tell how strong
a race gas is by the way it smells?
FALSE: The characteristic
“gasoline” small is caused by contaminants in the fuel such as phosphorus
and sulfur compounds. In addition, modern race fuels use non-traditional
components such as oxygenates which have a distinctly different odor. Lastly,
refineries will sometimes add an odorant (or colorant) to a fuel to aid
in its quick and easy identification. Unless a fuel contains a specific
compound which can be properly identified by its color, the smell of gasoline
only tells you that your nose is working.
Answers courtesy of Phillips
66 Racing Fuels.
END
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