EYE ON THE INDUSTRY
01-01-01
By Darrell Sitarz
"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.