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<blockquote data-quote="-Chip-" data-source="post: 3526937" data-attributes="member: 34786"><p>Sure Neil!</p><p></p><p><strong>YOU ASK QUESTIONS, THEN YOU GET ANSWERS </strong></p><p></p><p><strong>Q: How are racing fuels made? </strong></p><p></p><p><strong>A:</strong> All gasoline contains the same general family of hydrocarbons; low test, high test, racing gas and aviation gas. General refiners are set up to make a large volume of gasoline, hundreds of thousands of gallons per day to satisfy their retail market. </p><p></p><p>Making a racing gas goes like this: you start with a blending stock of gas, then you add your own additives to end up with whatever octane level you're after. A blending gas is a raw, basic gasoline, with no additives or detergents. </p><p></p><p>Iso-octane is an example of one that can be used. You have to calculate what you want in a racing gas before you start adding things to a blending stock, or even what kind of blending stock you start with. </p><p></p><p>For example, for the fuel that we make, we want to end up with an octane of approximately 108 research method, with a motor octane that will blend back to about right at 103-104 RM-over2. That's an average of research and motor methods of testing octane and is the most commonly accepted rating. </p><p></p><p>We add lead, lead scavengers, various aromatics, napthanics and light-end hydrocarbons to get the correct Read Vapor Pressure to control vapor lock. You have to change gasoline from a liquid to a vapor to get it into a proper state for an air/fuel mixture ratio, so the spark plug can ignite it. A carburetor does this job of turning the liquid into a vapor. </p><p></p><p><strong>Q:</strong> We see ads all the time, this gas has 102 octane, this gas has 115 octane, or another with 118. What do we need? Let's say you have an engine with 8.5 to 1 compression ratio. How much octane does it require? </p><p></p><p><strong>A:</strong> That's a tough question. It has a lot to do with the combustion chamber shape, location of the spark plug, condition of the combustion chamber, the air/fuel ratio you enter into it, a huge number of factors including the air temperature and the load the engine is put under. </p><p></p><p>What we're talking about is trying to defeat detonation; that's the real problem. I can give you some approximate guidelines. If you're using a 10 to 1 engine and over, you need racing fuel. On a 9:1 engine, you're probably in the 98 octane area, and there are a lot of good strong 9 to 1 engines out there. </p><p></p><p>There is no real linear type of relationship between compression ratio and the octane requirements. You can have an engine with extremely high compression and really have a low octane requirement. I know people who have had engines in the 13, 14 or 15 to 1 compression ratio range and have used 103 to 104 octane fuel with no problems. </p><p></p><p><strong>GOOD GAS/BAD GAS: MAKING IT HAPPEN </strong></p><p></p><p><strong>Q: </strong>What makes a good racing gasoline? Any secrets you'd like to give away? </p><p></p><p><strong>A:</strong> We buy a blending stock from two different companies? There are two different stocks and we co-mingle those. Now this is important: these stocks are sold by an ASTM specification and it means they'll be the same quality and molecular weight each time. </p><p></p><p>We try to control the variables as tightly as possible, by buying the same group of chemicals, time after time, with the same chemical characteristics. What we end up doing is giving you a base fuel that you can tune with and use, and it doesn't change. </p><p></p><p>It has the same chemical components, the same chemical characteristics, the same specific gravity and all of this is very important for consistency. A racer doesn't want to change the variables. And fuel is one of them. </p><p></p><p>We've done our own testing, and without naming names, I can tell you some startling facts. We've sent samples of certain racing fuels to the lab for testing, and one time it's 114 octane, and a month later the same brand of fuel tests out to be 108. It's got a specific gravity of .76 one time and the next batch tests out at .73. You splash it in the motor one time and it runs great. The next time, the specific gravity of the fuel is different and it flows differently. Different specific gravity fuels flow through the carburetor jets at different flow rates. </p><p></p><p>By just changing the fuel, you can richen or lean your engine out. Let's say a major refiner wants to make an 86 octane fuel and they want it blended as economically as possible. The building blocks used to make a higher octane fuel are expensive! The benzenes, toluenes, xylene complexes - or the BTX complexes - they want to use as little of these as possible. That's why lead was always so effective; because they could splash a lot of lead in it and bring the octane way up, and do it really cheap. These major refineries are only making a cent, two cents or three cents a gallon profit once the smoke clears. They have to keep production costs down. </p><p></p><p>You're not under that restriction with racing fuel, because these fuels usually cost three dollars a gallon or more and the profit potential is greater, at least on a per-gallon basis. </p><p></p><p>With this in mind, you should be able to make a good fuel, with repeatable characteristics, time after time. This is the single most important thing to look for in a racing fuel, I feel. </p><p><strong></strong></p><p><strong>Q:</strong> More important than high octane numbers? </p><p></p><p><strong>A:</strong> Absolutely! Look, if you had a bike where you used a dozen pipes during testing, and all of them were different, you wouldn't know where you were at! You couldn't time the motor... you couldn't jet it. </p><p></p><p>Take a drag racer, for example. He might go through three or four sets of pistons in a race. If each piston had a different compression ratio, how would they know what to do? They'd be lost. So the important thing in any racing situation, is to have the same kind of fuel, day after day, time after time, year after year. </p><p><strong></strong></p><p><strong>WHY DOES RACE GAS COST SO MUCH? </strong></p><p></p><p>Q: So the real expense for racing fuel is in the quality control, the assurance that it's consistent all the time. Why can't this be done with pump gas? </p><p></p><p>A: For a major refiner to make racing fuel is out of the question; he's not going to touch it. It's a pain in the butt to make; there's a lot of quality control that has to be done and there has to be a level of cleanliness you're not going to find in volume production. </p><p></p><p>Q: How can we, the consumers, tell a good racing fuel from one of lesser quality? </p><p></p><p>A: Given that they all can provide you with an octane, say 103, it may be just window dressing. A lot of people think that by buying a higher octane, it'll make your bike get to the finish line quicker and you may do better. </p><p></p><p>As to usability in a motor, ultra-high numbers are questionable. Octane will make up for some sins that an engine builder might have built into the motor, but an engine only needs what it needs... not a bit more. </p><p></p><p>What makes a fuel better? Our fuel has been identical for 15 years ... same specific gravity, same Read Vapor Pressure, same octane, whether it be research or motor method of rating. Some people advertise outrageously high octane readings, which makes it particularly attractive to people who don't understand what they need. </p><p></p><p><strong>TOO MUCH OCTANE CAN BE BAD! </strong></p><p></p><p>Right now in the racing fuel business, there's a race to market the highest octane fuel that you can make. People relate the highest octane to "my motor is making more power." That couldn't be further from the truth. </p><p></p><p>One of the downsides to building a fuel with ultra-high octane is adding components that really slow down the flame front in the combustion process. You can get the flame front so slow, that the engine is now running in a too-rich condition. This takes away horsepower. So here you are, slowing down the flame front and getting rid of detonation, at the expense of losing horsepower. </p><p></p><p>I see this all the time at the track. I see engines running "heavy"; they're trying to tune it to lean it out, when actually the flame front is causing the problem. </p><p></p><p>Q: Are there good ways to get the good octane numbers and are there bad ways? I guess our question is, are there shortcuts? </p><p></p><p>A: I've seen some fuels with compositions of 25 to 30 percent aromatic content. Aromatics are a reliable, correct way to build octane, but people tend to think that if a little bit is good, then more ought to be better and a whole lot is just great! </p><p></p><p>If you run reliable lab tests on octane and incrementally increase the aromatic content, most lab people feel that if you get up above the 10 to 15 percent aromatic content, your octane falls off. </p><p></p><p>What the engine does is start making more heat, which requires more octane, which makes more heat: a real vicious cycle. It's like a dog chasing its own tail. </p><p></p><p>The bottom line is this: let's say your motor needs 92 octane to run correctly and you fill up with 125 octane wonder gas. You will not run any faster. In fact, you might end up running slower because of a radically slowed flame front. </p><p></p><p><strong>MIXING THE GOOD STUFF WITH THE BAD STUFF </strong></p><p></p><p>Q: Let's say that we have a racer on a budget. He's got a lightly modified engine and would like to run racing gas, but can't afford it. Can he mix race gas with pump gas and, if so, what ratios? </p><p></p><p>A: On a stock motor, I don't think the racer would need to run racing gas, except during the summer when it's very hot. Here, you stand a very real chance of vapor lock with pump gas. I'd recommend that the racer start out with a good stock major brand gasoline of at least 92 octane rating, then go out and test. </p><p></p><p>If the engine runs fine and doesn't ping or detonate, that's fine. You can use that gas. Just make sure you buy it at a very busy corner with a high volume turnover. This way you stand a better chance of getting fresh gas, and no substitute gas. </p><p></p><p>If you do have some pinging and detonation, try one gallon of racing fuel to three gallons of pump gas. In a stock motor, this should do it. Test it again under the same circumstances to check it out. You're going to have to check this regularly, because the variables in the street gasoline WILL CHANGE, while the variables in a good racing fuel will not. </p><p></p><p>The combination of 92 octane street gas and 103 octane racing gas will kick up the actual octane two or three points. There's no real chart you can draw... it's not a linear thing. But that's all it might take to make the motor happy. </p><p></p><p>Here's something startling, and I almost hesitate to say it. You don't get any increase in the performance with racing fuel. Not a bit. Not any racing gas. Good racing fuel allows you to run your timing more radical, to extract more horsepower out of what you've got. </p><p></p><p>I can take any racing fuel made - including ours - and make the engine hammer and detonate by have the timing set too far out. Timing lead is critical. You want to make the engine ping? Easy, just add too much lead. Conversely, running the timing closer to top dead center will cool things down. Remember the TT bikes of ten years ago? They ran so much lead, they could not be kick started. They had to be push started. </p><p></p><p><strong>HOW TO KNOW WHAT YOU'RE GETTING </strong></p><p></p><p>I would not buy any racing gas, or pump gas, with alcohol in it. That's the first thing I'd ask ... "Does it have any alcohol?" It's not that you can't use alcohol. Ethyl alcohol is a good additive; it can be used up to ten percent in most cars. </p><p></p><p>Alcohol really offers a different fuel/air ratio than gasoline. Racers who do run alcohol have to use enormous jets and really drink the stuff through the carb. </p><p></p><p>Make sure that the fuel does not have MTBE in it. It's a very effective new additive, but it may be illegal in your organization, as it is in many. It's an oxygen or nitrogen bearing com-pound. </p><p></p><p>Probably the single best option is to test with a hydrometer several containers of the racing gas you're considering buying. This will give you the specific gravity of the fuel, and if it varies from container to container, it will tell you a very sad story about quality control. </p><p></p><p>You can buy a gas testing hydrometer for about four or five bucks. All savvy tuners test with them BEFORE they start tuning, or if they cannot use their regular gas. </p><p><strong></strong></p><p><strong>AVIATION GAS: MYTHS AND FACTS </strong></p><p></p><p>Q: What about using AV, or aviation, gas? </p><p></p><p>A: There's an old wives' tale about AV gas out of World War II and I don't know who started this, but it says that if you put AV gas in your car, you'll burn the valves. There's no doubt that aviation fuel can be used in any internal combustion engine that's driven up and down the highway at cruising speeds. </p><p></p><p>It doesn't make much sense to use it for that since it goes for something like $1.75 or $1.85 in this area, and is not easily obtainable. </p><p></p><p>A motorcycle and an airplane really live in two different environments. An airplane generally takes off, climbs to its altitude and the general outside temperature is at or below zero. Even in the summertime, it maxes out at 10 or 20 degrees above. And an air-plane does not turn high rpm. A typical prop job loafs along at two to three thousand rpm. Of course, there are some high perfor-mance exceptions. The engine just drones along at low power settings, except for take-offs.</p><p></p><p>Here are some more food for thought:</p><p></p><p>It all comes down to fuel. You can build the hottest, most throw-down thumpin’ big block that ever existed, but it’s gotta have good gas.</p><p></p><p>What is good gas anyway? What separates the killer stuff for your NMCA Pro-Streeter from the slag your lawnmower barely runs on? After consulting experts in the field, we decided to check into the various street fuels available, various types and grades of octane booster, aviation gasoline (AvGas), and racing fuels. By comparing the different options available to you, it may be easier to choose the best grade for your ride.</p><p></p><p>What is octane anyway? Octane is a measurement of a fuel’s resistance to ignition. Ideally, the air/fuel mixture will ignite at the proper time and burn smoothly through the power stroke. The idea is, one powerful combustion of better than several. randomly-ignited small flame fronts. When you can precisely control the point at which the fuel will ignite, maximum performance of the engine can be achieved, and power-robbing knock and ping will be eliminated. Knock and ping are a result of abnormal ignition, or multiple flame fronts colliding within the combustion chamber during the compression stroke.</p><p></p><p>All reputable fuel manufacturers determine the octane rating of their gasoline in the research lab using a special, dedicated single cylinder engine. Comparing the gasoline to a series of standard reference fuels in the test engine results in either a research octane number (RON) or a motor octane number (MON) depending on a set of operating conditions. The RON is determined with the test engine operating at 600rpm, at standard barometric pressure, and the intake air temperature set at 125 degrees Fahrenheit. RON is primarily used to address part-throttle knock and ping problems. The MON addresses wide open throttle operation and is determined with the test engine spinning at 900rpm, also at standard barometric pressure, and the intake air temperature pumped up to 300 degrees.</p><p></p><p>The best predictor of a fuel’s performance in a street/strip machine is the Anti-Knock Index (AKI). This is simply the average of the RON and MON numbers, or (RON+MON)/2. Most all octane ratings posted at the pumps are determined by this AKI formula, and are the minimum values you could expect to see. The minimum octane requirement of your engine is determined by several variables besides the compression ratio. The engine and cylinder head configuration, air/fuel mixture, timing, coolant temperature, atmospheric pressure, relative humidity, and ambient air temperature will also affect the octane required to make your mill produce maximum power.</p><p></p><p>The burn rate of a fuel is a measurement of the time required for complete combustion of the air/fuel mixture. The notion that octane ratings affect the burn rate of fuel is about 180-degrees from reality. Burn rate is a function of several variables, and the two are completely independent, although there is generally a correlation between octane ratings and burn rates.</p><p></p><p>To give you a good example of this, we contacted Jim Wurth from Sunoco Race Fuels. He explains, "A perfect example is Sunoco Maximal, which is our fastest burning fuel, and coincidentally one of Sunoco’s highest octane fuels at 116 (R+M)/2. A lot of Pro Stock teams rely on Maximal for those sub-seven second runs. When they are turning 9,000rpm or more, the fuel has to burn pretty quickly to achieve complete combustion."</p><p></p><p>Octane boosters offer little help in the quest for higher octane. Most popular street-legal octane boosters claim increases in octane ratings up to five points, and those boosters intended for off-road use only claim up to seven points. That’s a lot of octane to hope for simply by pouring an additive in a tank. Sunoco told us that before they launched their GT-100 Unleaded retail pilot program, they wanted to be sure that a 100 (R+M)/2 octane street-legal fuel would be of value, and that enthusiasts would not be able to get the same (or better) results using an octane booster. Nine of the most popular retail octane boosters were put through a series of tests to determine where the consumer could get the most bang for the buck. The test results were verified by an independent testing facility, using several brands of regular unleaded and premium gasolines, just to make sure everything was legit.</p><p></p><p>According to Mark Borosky, Vehicle Test Engineer for Sunoco, "Of the nine octane boosters tested, none showed a significant increase, and one actually lowered the octane number of the test gasolines." Testing repeatedly showed a maximum increase in octane of 3.5 points by only two of the six street-legal octane boosters when the recommended treatment rate was blended with lower base 87-octane gasoline. The best the remaining four products could muster was less than a one point increase. "While clearly no one would actually use an octane booster in a low base octane fuel, we wanted to give the manufacturers the benefit of the doubt relative to their claims of five-to-seven point increases" explained Borosky.</p><p></p><p>When tests were performed using 98 and 94-octane fuel, even the two best products from the previous tests produced a disappointing 1.5 to 2 point maximum increase. The remaining four street-legal octane boosters showed less than a .5 point increase. Those products designated for off-road use only didn’t fare any better than the street-legal products. Subsequent tests where the dosage of octane booster was doubled, tripled, and even quadrupled produced only minimal improvements in octane, regardless of the base octane hum-ber of the test gas. In fact, quadrupling the treatment rate of the most powerful additive produced only a 3.5 point increase in octane when added to 98 premium, resulting in a cost of $3.25 a gallon.</p><p></p><p>An alternative path to octane euphoria is to blend gasolines of different octane levels yourself. It’s easier than you may think, safe, and the results are predictable. The formula for mixing gasolines of the same type is pretty straightforward. When you mix a 50/50 blend of two unleaded fuels, simply average the two octane ratings to determine what’s in the tank. If you mix 94 and 100, you get 97. The same generally holds true for leaded gasolines, assuming the lead content is nearly equal.</p><p></p><p>Blending a leaded fuel with unleaded, however, pushes the octane up a bit more than the math would suggest, due to the effect of the lead. Just a gram or two of lead blended into the unleaded fuel will raise the octane number significantly. Commercial leaded racing fuels contain anywhere from a trace to six grams of lead per gallon. If you were to mix 50 percent 110 octane leaded fuel with 100 octane unleaded, you would actually end up with an octane number around 106 to 107. Keep in mind that even the smallest amount of lead or leaded gasoline with unleaded, could spell the end of your catalytic converter or oxygen sensor. The same holds true for using octane boosters intended for off-road use only. A word to the wise, check for any lead content in all the additives you might mix with your unleaded gasoline. And check with your state emissions regulations for street use.</p><p></p><p>We asked Sunoco’s Wurth about using aviation fuel in an automobile engine. He was emphatic when he said, "Don’t do it. Even though Sunoco is a major producer of aviation fuel, this fuel is specifically blended for aircraft engines. Aircraft operate under very different conditions than automobiles, and the fuel requirements are quite different as well. Aircraft engines generally use very small pistons and run within a very narrow rpm range. There’s no need for transient throttle response in an airplane because after the pilot does the initial engine run-up, the throttle is set in one position and the rpm doesn’t normally change until landing. Also, airplanes fly where the air is cold and thin, and the atmospheric pressure is low. These are not even close to the conditions your street machine will see on the ground. Also, since most piston-driven aircraft cruise at 3,000rpm or so, the burn rate of aviation gas is much too slow for any high-performance automotive applications."</p><p></p><p>What is it that makes race gas so different? What’s it made of? Sunoco tells us their GT PLUS 104 octane unleaded race gas is only 15-20 percent traditional gasoline, and about 85 percent additives! Actually there are about 120 different chemicals in GT PLUS. One reason it isn’t street legal is the high oxygen content. The EPA requires that the oxygen content of a street legal fuel cannot exceed 2.9 percent. GT PLUS is about 3.5 percent oxygen. This fuel is light in weight at only 6.14 1bs-per-gallon. The high oxygen content improves the octane, and when the induction system is properly calibrated, this fuel will help make additional horsepower. The high oxygen content has a supercharging effect, since 3.5 percent oxygen is the equivalent to about 17 percent more air. Different fuels can actually alter horsepower 5-to-10 percent or more.</p><p></p><p>We wanted to know more about the different types of race gas Sunoco had, and didn’t realize there were five different types of racing fuel alone.</p><p></p><p>GT-100 Unleaded, is a clear fuel with a pump octane of 100, and will handle compression ratios of up to 12:1, and is street legal in all 50 states.</p><p></p><p>GT PLUS, is also unleaded, and is rated at 104 octane. It is suitable for compression ratios up to 14:1 and is colored light blue. It will not harm oxygen sensors or knock sensors in computer controlled engines. It is not street legal.</p><p></p><p>STANDARD, is a leaded fuel rated at 110 octane, is colored purple and is intended for drag racing, road racing, and race boats.</p><p></p><p>SUPREME, also a leaded fuel, rated at 112 octane, is dark blue. It was developed to help resist vapor lock and meet the demands of sportsman, modifieds, offshore powerboats, and endurance racing where engines regularly run in excess of 7,000rpm.</p><p></p><p>MAXIMAL, we mentioned earlier, is colored red, has 116 octane, and is leaded. It is intended for exceptionally high performance applications, like Pro Stock, where extremely high cylinder pressures are common. Its extremely fast burn rate is satisfactory where rpm exceeds 10,000.</p><p></p><p>Now that you’re an expert on gasolines, you probably would like to know where to buy and store the stuff. If you are fortunate enough to live in the mid-Atlantic states, you can take advantage of Sunoco’s GT-100 Unleaded retail pilot program and get 100-octane race fuel at pumps located at select service stations. The rest of us have to purchase from local speed shops, at race tracks, or directly from Sunoco distributors.</p><p></p><p>When you plan on buying fuel in quantity, say a 55-gallon drum, you’ll be happy to know that racing fuel has a shelf life of about a year, if you store it properly. The container must conform to all safety standards, and should be made from metal or polymer. Make sure the container is opaque and solid in color. The white plastic jugs we see at the track should be used for short-term storage only. They let in sunlight, which will affect the fuel The lead in leaded fuel and other chemicals in unleaded fuel are photosensitive, and will dissipate if they are exposed to the sun. Keep any container tightly sealed to prevent evaporation.</p></blockquote><p></p>
[QUOTE="-Chip-, post: 3526937, member: 34786"] Sure Neil! [B]YOU ASK QUESTIONS, THEN YOU GET ANSWERS [/B] [B]Q: How are racing fuels made? [/B] [B]A:[/B] All gasoline contains the same general family of hydrocarbons; low test, high test, racing gas and aviation gas. General refiners are set up to make a large volume of gasoline, hundreds of thousands of gallons per day to satisfy their retail market. Making a racing gas goes like this: you start with a blending stock of gas, then you add your own additives to end up with whatever octane level you're after. A blending gas is a raw, basic gasoline, with no additives or detergents. Iso-octane is an example of one that can be used. You have to calculate what you want in a racing gas before you start adding things to a blending stock, or even what kind of blending stock you start with. For example, for the fuel that we make, we want to end up with an octane of approximately 108 research method, with a motor octane that will blend back to about right at 103-104 RM-over2. That's an average of research and motor methods of testing octane and is the most commonly accepted rating. We add lead, lead scavengers, various aromatics, napthanics and light-end hydrocarbons to get the correct Read Vapor Pressure to control vapor lock. You have to change gasoline from a liquid to a vapor to get it into a proper state for an air/fuel mixture ratio, so the spark plug can ignite it. A carburetor does this job of turning the liquid into a vapor. [B]Q:[/B] We see ads all the time, this gas has 102 octane, this gas has 115 octane, or another with 118. What do we need? Let's say you have an engine with 8.5 to 1 compression ratio. How much octane does it require? [B]A:[/B] That's a tough question. It has a lot to do with the combustion chamber shape, location of the spark plug, condition of the combustion chamber, the air/fuel ratio you enter into it, a huge number of factors including the air temperature and the load the engine is put under. What we're talking about is trying to defeat detonation; that's the real problem. I can give you some approximate guidelines. If you're using a 10 to 1 engine and over, you need racing fuel. On a 9:1 engine, you're probably in the 98 octane area, and there are a lot of good strong 9 to 1 engines out there. There is no real linear type of relationship between compression ratio and the octane requirements. You can have an engine with extremely high compression and really have a low octane requirement. I know people who have had engines in the 13, 14 or 15 to 1 compression ratio range and have used 103 to 104 octane fuel with no problems. [B]GOOD GAS/BAD GAS: MAKING IT HAPPEN [/B] [B]Q: [/B]What makes a good racing gasoline? Any secrets you'd like to give away? [B]A:[/B] We buy a blending stock from two different companies? There are two different stocks and we co-mingle those. Now this is important: these stocks are sold by an ASTM specification and it means they'll be the same quality and molecular weight each time. We try to control the variables as tightly as possible, by buying the same group of chemicals, time after time, with the same chemical characteristics. What we end up doing is giving you a base fuel that you can tune with and use, and it doesn't change. It has the same chemical components, the same chemical characteristics, the same specific gravity and all of this is very important for consistency. A racer doesn't want to change the variables. And fuel is one of them. We've done our own testing, and without naming names, I can tell you some startling facts. We've sent samples of certain racing fuels to the lab for testing, and one time it's 114 octane, and a month later the same brand of fuel tests out to be 108. It's got a specific gravity of .76 one time and the next batch tests out at .73. You splash it in the motor one time and it runs great. The next time, the specific gravity of the fuel is different and it flows differently. Different specific gravity fuels flow through the carburetor jets at different flow rates. By just changing the fuel, you can richen or lean your engine out. Let's say a major refiner wants to make an 86 octane fuel and they want it blended as economically as possible. The building blocks used to make a higher octane fuel are expensive! The benzenes, toluenes, xylene complexes - or the BTX complexes - they want to use as little of these as possible. That's why lead was always so effective; because they could splash a lot of lead in it and bring the octane way up, and do it really cheap. These major refineries are only making a cent, two cents or three cents a gallon profit once the smoke clears. They have to keep production costs down. You're not under that restriction with racing fuel, because these fuels usually cost three dollars a gallon or more and the profit potential is greater, at least on a per-gallon basis. With this in mind, you should be able to make a good fuel, with repeatable characteristics, time after time. This is the single most important thing to look for in a racing fuel, I feel. [B] Q:[/B] More important than high octane numbers? [B]A:[/B] Absolutely! Look, if you had a bike where you used a dozen pipes during testing, and all of them were different, you wouldn't know where you were at! You couldn't time the motor... you couldn't jet it. Take a drag racer, for example. He might go through three or four sets of pistons in a race. If each piston had a different compression ratio, how would they know what to do? They'd be lost. So the important thing in any racing situation, is to have the same kind of fuel, day after day, time after time, year after year. [B] WHY DOES RACE GAS COST SO MUCH? [/B] Q: So the real expense for racing fuel is in the quality control, the assurance that it's consistent all the time. Why can't this be done with pump gas? A: For a major refiner to make racing fuel is out of the question; he's not going to touch it. It's a pain in the butt to make; there's a lot of quality control that has to be done and there has to be a level of cleanliness you're not going to find in volume production. Q: How can we, the consumers, tell a good racing fuel from one of lesser quality? A: Given that they all can provide you with an octane, say 103, it may be just window dressing. A lot of people think that by buying a higher octane, it'll make your bike get to the finish line quicker and you may do better. As to usability in a motor, ultra-high numbers are questionable. Octane will make up for some sins that an engine builder might have built into the motor, but an engine only needs what it needs... not a bit more. What makes a fuel better? Our fuel has been identical for 15 years ... same specific gravity, same Read Vapor Pressure, same octane, whether it be research or motor method of rating. Some people advertise outrageously high octane readings, which makes it particularly attractive to people who don't understand what they need. [B]TOO MUCH OCTANE CAN BE BAD! [/B] Right now in the racing fuel business, there's a race to market the highest octane fuel that you can make. People relate the highest octane to "my motor is making more power." That couldn't be further from the truth. One of the downsides to building a fuel with ultra-high octane is adding components that really slow down the flame front in the combustion process. You can get the flame front so slow, that the engine is now running in a too-rich condition. This takes away horsepower. So here you are, slowing down the flame front and getting rid of detonation, at the expense of losing horsepower. I see this all the time at the track. I see engines running "heavy"; they're trying to tune it to lean it out, when actually the flame front is causing the problem. Q: Are there good ways to get the good octane numbers and are there bad ways? I guess our question is, are there shortcuts? A: I've seen some fuels with compositions of 25 to 30 percent aromatic content. Aromatics are a reliable, correct way to build octane, but people tend to think that if a little bit is good, then more ought to be better and a whole lot is just great! If you run reliable lab tests on octane and incrementally increase the aromatic content, most lab people feel that if you get up above the 10 to 15 percent aromatic content, your octane falls off. What the engine does is start making more heat, which requires more octane, which makes more heat: a real vicious cycle. It's like a dog chasing its own tail. The bottom line is this: let's say your motor needs 92 octane to run correctly and you fill up with 125 octane wonder gas. You will not run any faster. In fact, you might end up running slower because of a radically slowed flame front. [B]MIXING THE GOOD STUFF WITH THE BAD STUFF [/B] Q: Let's say that we have a racer on a budget. He's got a lightly modified engine and would like to run racing gas, but can't afford it. Can he mix race gas with pump gas and, if so, what ratios? A: On a stock motor, I don't think the racer would need to run racing gas, except during the summer when it's very hot. Here, you stand a very real chance of vapor lock with pump gas. I'd recommend that the racer start out with a good stock major brand gasoline of at least 92 octane rating, then go out and test. If the engine runs fine and doesn't ping or detonate, that's fine. You can use that gas. Just make sure you buy it at a very busy corner with a high volume turnover. This way you stand a better chance of getting fresh gas, and no substitute gas. If you do have some pinging and detonation, try one gallon of racing fuel to three gallons of pump gas. In a stock motor, this should do it. Test it again under the same circumstances to check it out. You're going to have to check this regularly, because the variables in the street gasoline WILL CHANGE, while the variables in a good racing fuel will not. The combination of 92 octane street gas and 103 octane racing gas will kick up the actual octane two or three points. There's no real chart you can draw... it's not a linear thing. But that's all it might take to make the motor happy. Here's something startling, and I almost hesitate to say it. You don't get any increase in the performance with racing fuel. Not a bit. Not any racing gas. Good racing fuel allows you to run your timing more radical, to extract more horsepower out of what you've got. I can take any racing fuel made - including ours - and make the engine hammer and detonate by have the timing set too far out. Timing lead is critical. You want to make the engine ping? Easy, just add too much lead. Conversely, running the timing closer to top dead center will cool things down. Remember the TT bikes of ten years ago? They ran so much lead, they could not be kick started. They had to be push started. [B]HOW TO KNOW WHAT YOU'RE GETTING [/B] I would not buy any racing gas, or pump gas, with alcohol in it. That's the first thing I'd ask ... "Does it have any alcohol?" It's not that you can't use alcohol. Ethyl alcohol is a good additive; it can be used up to ten percent in most cars. Alcohol really offers a different fuel/air ratio than gasoline. Racers who do run alcohol have to use enormous jets and really drink the stuff through the carb. Make sure that the fuel does not have MTBE in it. It's a very effective new additive, but it may be illegal in your organization, as it is in many. It's an oxygen or nitrogen bearing com-pound. Probably the single best option is to test with a hydrometer several containers of the racing gas you're considering buying. This will give you the specific gravity of the fuel, and if it varies from container to container, it will tell you a very sad story about quality control. You can buy a gas testing hydrometer for about four or five bucks. All savvy tuners test with them BEFORE they start tuning, or if they cannot use their regular gas. [B] AVIATION GAS: MYTHS AND FACTS [/B] Q: What about using AV, or aviation, gas? A: There's an old wives' tale about AV gas out of World War II and I don't know who started this, but it says that if you put AV gas in your car, you'll burn the valves. There's no doubt that aviation fuel can be used in any internal combustion engine that's driven up and down the highway at cruising speeds. It doesn't make much sense to use it for that since it goes for something like $1.75 or $1.85 in this area, and is not easily obtainable. A motorcycle and an airplane really live in two different environments. An airplane generally takes off, climbs to its altitude and the general outside temperature is at or below zero. Even in the summertime, it maxes out at 10 or 20 degrees above. And an air-plane does not turn high rpm. A typical prop job loafs along at two to three thousand rpm. Of course, there are some high perfor-mance exceptions. The engine just drones along at low power settings, except for take-offs. Here are some more food for thought: It all comes down to fuel. You can build the hottest, most throw-down thumpin’ big block that ever existed, but it’s gotta have good gas. What is good gas anyway? What separates the killer stuff for your NMCA Pro-Streeter from the slag your lawnmower barely runs on? After consulting experts in the field, we decided to check into the various street fuels available, various types and grades of octane booster, aviation gasoline (AvGas), and racing fuels. By comparing the different options available to you, it may be easier to choose the best grade for your ride. What is octane anyway? Octane is a measurement of a fuel’s resistance to ignition. Ideally, the air/fuel mixture will ignite at the proper time and burn smoothly through the power stroke. The idea is, one powerful combustion of better than several. randomly-ignited small flame fronts. When you can precisely control the point at which the fuel will ignite, maximum performance of the engine can be achieved, and power-robbing knock and ping will be eliminated. Knock and ping are a result of abnormal ignition, or multiple flame fronts colliding within the combustion chamber during the compression stroke. All reputable fuel manufacturers determine the octane rating of their gasoline in the research lab using a special, dedicated single cylinder engine. Comparing the gasoline to a series of standard reference fuels in the test engine results in either a research octane number (RON) or a motor octane number (MON) depending on a set of operating conditions. The RON is determined with the test engine operating at 600rpm, at standard barometric pressure, and the intake air temperature set at 125 degrees Fahrenheit. RON is primarily used to address part-throttle knock and ping problems. The MON addresses wide open throttle operation and is determined with the test engine spinning at 900rpm, also at standard barometric pressure, and the intake air temperature pumped up to 300 degrees. The best predictor of a fuel’s performance in a street/strip machine is the Anti-Knock Index (AKI). This is simply the average of the RON and MON numbers, or (RON+MON)/2. Most all octane ratings posted at the pumps are determined by this AKI formula, and are the minimum values you could expect to see. The minimum octane requirement of your engine is determined by several variables besides the compression ratio. The engine and cylinder head configuration, air/fuel mixture, timing, coolant temperature, atmospheric pressure, relative humidity, and ambient air temperature will also affect the octane required to make your mill produce maximum power. The burn rate of a fuel is a measurement of the time required for complete combustion of the air/fuel mixture. The notion that octane ratings affect the burn rate of fuel is about 180-degrees from reality. Burn rate is a function of several variables, and the two are completely independent, although there is generally a correlation between octane ratings and burn rates. To give you a good example of this, we contacted Jim Wurth from Sunoco Race Fuels. He explains, "A perfect example is Sunoco Maximal, which is our fastest burning fuel, and coincidentally one of Sunoco’s highest octane fuels at 116 (R+M)/2. A lot of Pro Stock teams rely on Maximal for those sub-seven second runs. When they are turning 9,000rpm or more, the fuel has to burn pretty quickly to achieve complete combustion." Octane boosters offer little help in the quest for higher octane. Most popular street-legal octane boosters claim increases in octane ratings up to five points, and those boosters intended for off-road use only claim up to seven points. That’s a lot of octane to hope for simply by pouring an additive in a tank. Sunoco told us that before they launched their GT-100 Unleaded retail pilot program, they wanted to be sure that a 100 (R+M)/2 octane street-legal fuel would be of value, and that enthusiasts would not be able to get the same (or better) results using an octane booster. Nine of the most popular retail octane boosters were put through a series of tests to determine where the consumer could get the most bang for the buck. The test results were verified by an independent testing facility, using several brands of regular unleaded and premium gasolines, just to make sure everything was legit. According to Mark Borosky, Vehicle Test Engineer for Sunoco, "Of the nine octane boosters tested, none showed a significant increase, and one actually lowered the octane number of the test gasolines." Testing repeatedly showed a maximum increase in octane of 3.5 points by only two of the six street-legal octane boosters when the recommended treatment rate was blended with lower base 87-octane gasoline. The best the remaining four products could muster was less than a one point increase. "While clearly no one would actually use an octane booster in a low base octane fuel, we wanted to give the manufacturers the benefit of the doubt relative to their claims of five-to-seven point increases" explained Borosky. When tests were performed using 98 and 94-octane fuel, even the two best products from the previous tests produced a disappointing 1.5 to 2 point maximum increase. The remaining four street-legal octane boosters showed less than a .5 point increase. Those products designated for off-road use only didn’t fare any better than the street-legal products. Subsequent tests where the dosage of octane booster was doubled, tripled, and even quadrupled produced only minimal improvements in octane, regardless of the base octane hum-ber of the test gas. In fact, quadrupling the treatment rate of the most powerful additive produced only a 3.5 point increase in octane when added to 98 premium, resulting in a cost of $3.25 a gallon. An alternative path to octane euphoria is to blend gasolines of different octane levels yourself. It’s easier than you may think, safe, and the results are predictable. The formula for mixing gasolines of the same type is pretty straightforward. When you mix a 50/50 blend of two unleaded fuels, simply average the two octane ratings to determine what’s in the tank. If you mix 94 and 100, you get 97. The same generally holds true for leaded gasolines, assuming the lead content is nearly equal. Blending a leaded fuel with unleaded, however, pushes the octane up a bit more than the math would suggest, due to the effect of the lead. Just a gram or two of lead blended into the unleaded fuel will raise the octane number significantly. Commercial leaded racing fuels contain anywhere from a trace to six grams of lead per gallon. If you were to mix 50 percent 110 octane leaded fuel with 100 octane unleaded, you would actually end up with an octane number around 106 to 107. Keep in mind that even the smallest amount of lead or leaded gasoline with unleaded, could spell the end of your catalytic converter or oxygen sensor. The same holds true for using octane boosters intended for off-road use only. A word to the wise, check for any lead content in all the additives you might mix with your unleaded gasoline. And check with your state emissions regulations for street use. We asked Sunoco’s Wurth about using aviation fuel in an automobile engine. He was emphatic when he said, "Don’t do it. Even though Sunoco is a major producer of aviation fuel, this fuel is specifically blended for aircraft engines. Aircraft operate under very different conditions than automobiles, and the fuel requirements are quite different as well. Aircraft engines generally use very small pistons and run within a very narrow rpm range. There’s no need for transient throttle response in an airplane because after the pilot does the initial engine run-up, the throttle is set in one position and the rpm doesn’t normally change until landing. Also, airplanes fly where the air is cold and thin, and the atmospheric pressure is low. These are not even close to the conditions your street machine will see on the ground. Also, since most piston-driven aircraft cruise at 3,000rpm or so, the burn rate of aviation gas is much too slow for any high-performance automotive applications." What is it that makes race gas so different? What’s it made of? Sunoco tells us their GT PLUS 104 octane unleaded race gas is only 15-20 percent traditional gasoline, and about 85 percent additives! Actually there are about 120 different chemicals in GT PLUS. One reason it isn’t street legal is the high oxygen content. The EPA requires that the oxygen content of a street legal fuel cannot exceed 2.9 percent. GT PLUS is about 3.5 percent oxygen. This fuel is light in weight at only 6.14 1bs-per-gallon. The high oxygen content improves the octane, and when the induction system is properly calibrated, this fuel will help make additional horsepower. The high oxygen content has a supercharging effect, since 3.5 percent oxygen is the equivalent to about 17 percent more air. Different fuels can actually alter horsepower 5-to-10 percent or more. We wanted to know more about the different types of race gas Sunoco had, and didn’t realize there were five different types of racing fuel alone. GT-100 Unleaded, is a clear fuel with a pump octane of 100, and will handle compression ratios of up to 12:1, and is street legal in all 50 states. GT PLUS, is also unleaded, and is rated at 104 octane. It is suitable for compression ratios up to 14:1 and is colored light blue. It will not harm oxygen sensors or knock sensors in computer controlled engines. It is not street legal. STANDARD, is a leaded fuel rated at 110 octane, is colored purple and is intended for drag racing, road racing, and race boats. SUPREME, also a leaded fuel, rated at 112 octane, is dark blue. It was developed to help resist vapor lock and meet the demands of sportsman, modifieds, offshore powerboats, and endurance racing where engines regularly run in excess of 7,000rpm. MAXIMAL, we mentioned earlier, is colored red, has 116 octane, and is leaded. It is intended for exceptionally high performance applications, like Pro Stock, where extremely high cylinder pressures are common. Its extremely fast burn rate is satisfactory where rpm exceeds 10,000. Now that you’re an expert on gasolines, you probably would like to know where to buy and store the stuff. If you are fortunate enough to live in the mid-Atlantic states, you can take advantage of Sunoco’s GT-100 Unleaded retail pilot program and get 100-octane race fuel at pumps located at select service stations. The rest of us have to purchase from local speed shops, at race tracks, or directly from Sunoco distributors. When you plan on buying fuel in quantity, say a 55-gallon drum, you’ll be happy to know that racing fuel has a shelf life of about a year, if you store it properly. The container must conform to all safety standards, and should be made from metal or polymer. Make sure the container is opaque and solid in color. The white plastic jugs we see at the track should be used for short-term storage only. They let in sunlight, which will affect the fuel The lead in leaded fuel and other chemicals in unleaded fuel are photosensitive, and will dissipate if they are exposed to the sun. Keep any container tightly sealed to prevent evaporation. [/QUOTE]
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