octane rating question
01-24-2004, 12:34 PM
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octane rating question
I understand that my new '04 Z roadster needs gas with a minimum octane rating of 91. When I lived in Ohio and Texas, I routinely saw octane ratings of 93 and 94. Now that I live in Utah, the highest rating I see is 91. Does anyone know why that is so? Does it have to do with the elevation (i.e., less oxygen in the air)?
Also, might I consider using a gas additive which would boost the octane, or do I risk damage to my car by doing so? Any help would be greatly appreciated.
Also, might I consider using a gas additive which would boost the octane, or do I risk damage to my car by doing so? Any help would be greatly appreciated.
01-24-2004, 02:58 PM
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The posted gasoline AKIs are lower in the Rocky Mountain states because less octane is needed at higher altitudes.
Aftermarket octane booster additives you can buy in a store will not improve performance if you use the correct gasoline grade to begin with. It likely will benefit only an older car with a high-compression engine.
A gasoline’s octane rating quantifies its resistance to knocking and pinging. These two sounds are caused by abnormal combustion, which robs power and can damage an engine. Knocking and pinging are basically the same thing; knocking is louder and represents a more serious condition. When they occur, it is during acceleration, though higher engine speeds tend to drown them out. Knocking sounds like someone repeatedly rapping the engine with a hammer, and the quieter pinging resembles marbles being shaken inside a tin can.
Many conditions in the engine itself can cause or promote combustion anomalies, but when all other factors are equal, gasoline with a higher octane rating is more resistant to knocking and pinging than a lower-octane fuel. So why doesn’t everyone just use high-octane gasoline? Because it is more expensive, and there is no advantage whatsoever in using premium gasoline in a car that doesn’t specifically require it. At one time, only premium gasoline included additives that prevent fuel-injector clogging; now, all grades are basically the same in this regard.
If your car requires high-octane gasoline and you habitually use regular gas because the engine exhibits no sign of knock, you’re outsmarting yourself. Most modern, computer-controlled engines include a knock sensor that detects knock and retards the ignition timing, causing the spark plugs to fire slightly later in the cycle. This typically prevents abnormal combustion and knock, which allows vehicles specified for premium fuel to run on lower-grade gasoline if it is all that’s available. While this removes the immediate hazard, it’s a bad idea to make a habit of running a vehicle on gasoline of lower-than-recommended octane. Retarding the spark causes a richer fuel/air mixture, which decreases fuel economy, increases emissions, causes the engine to run hotter, and reduces the longevity of both the engine itself and the catalytic converter. The money you save by pumping low-grade fuel into a car that demands higher octane is lost anyway, in decreased fuel economy and possibly gradual damage.
Your vehicle’s owner’s manual usually recommends an octane rating in terms of an Antiknock Index (AKI), which also is posted on gasoline pumps. The AKI is the average of two ratings determined in a laboratory: the Research Octane Number (RON), which corresponds with low-speed, mild-knocking conditions, and the Motor Octane Number (MON), which covers high-speed, high-temperature knocking conditions and part-throttle operation.
In general, three grades of gasoline are available in the United States: regular (AKI = 87), midgrade (AKI = 89) and premium (AKI = 91 to 94). The posted gasoline AKIs are lower in the Rocky Mountain states because less octane is needed at higher altitudes. Motorists whose cars require 91 octane fuel may find themselves at filling stations that offer only 89 and 93 octane, but nothing in between. In these cases, the options are to pay more for the 93 octane or to fill the tank halfway with 93 and the rest with 89. The resulting gasoline mixture, just like the average of their two AKI numbers, will equal 91 octane.
Premium fuel is mostly required by engines with high compression ratios and/or turbochargers or superchargers, for reasons explained in What Causes Knocking and Pinging.
Aftermarket Octane Boosters
Like higher-octane fuel from the pump, aftermarket octane booster additives you can buy in a store will not improve performance if you use the correct gasoline grade to begin with. It likely will benefit only an older car with a high-compression engine. There are three basic types of octane boosters:
Aromatic hydrocarbons, such as oxylene and toluene, which provide only a marginal octane increase.
Alcohols, such as methanol or ethanol, which are the most common and provide only a bit more boost.
Metallic octane boosters that contain methyl-cyclopentadienyl manganese (MMT), which are by far the most effective.
How Gasoline Octane Is Determined
A gasoline blend’s octane rating is determined by combusting it in a one-cylinder test engine and comparing its antiknock performance to that of standard, measurable reference fuels. The test engine allows the administrator to vary the compression and fuel/air mixture ratios — two factors that affect knock — with the goal of inducing a standard knock intensity, as measured by a knock meter.
All gasoline is a mixture of different hydrocarbons (hydrogen and carbon molecules of various configurations) ending in “ane,” as in hexane, nonane and dodecane. Two such hydrocarbons represent each end of the octane scale: Iso-octane has an octane rating of 100 and heptane a rating of 0. The technicians run the same engine on a blend of these two fuels and vary the ratio of each to the other until the knock intensity matches that of the gasoline under test. The percentage of iso-octane in that mixture — say, 93 percent iso-octane to 7 percent heptane — is the tested gasoline’s AKI rating: 93 octane.
How Gasoline Octane Is Controlled
Between 1923 and 1986, when leaded gas was sold in the United States, the accepted method of boosting octane ratings was to add tetraethyl lead (TEL) to gasoline. The sale of leaded gasoline in the United States is now prohibited because it contaminates the precious metals used in catalytic converters and it is considered harmful to people and the environment. Leaded gasoline is still used in less-developed parts of the world, because it’s cheaper to produce, and many of the older vehicles found in these countries require it for its additional lubrication properties.
Iso-octane would seem the perfect additive to vary gasoline octane ratings, but it is far too expensive. Refiners now use other metal-, alcohol- or hydrocarbon-based elements to vary octane in gasoline blends. The oxygenates added to create cleaner-burning reformulated gasoline (RFG), mainly methyl tertiary-butyl ether (MTBE) and ethanol, also boost octane. To learn more about reformulated gas and why it adds cost, see Oxygenates and Reformulated Gas.
Aftermarket octane booster additives you can buy in a store will not improve performance if you use the correct gasoline grade to begin with. It likely will benefit only an older car with a high-compression engine.
A gasoline’s octane rating quantifies its resistance to knocking and pinging. These two sounds are caused by abnormal combustion, which robs power and can damage an engine. Knocking and pinging are basically the same thing; knocking is louder and represents a more serious condition. When they occur, it is during acceleration, though higher engine speeds tend to drown them out. Knocking sounds like someone repeatedly rapping the engine with a hammer, and the quieter pinging resembles marbles being shaken inside a tin can.
Many conditions in the engine itself can cause or promote combustion anomalies, but when all other factors are equal, gasoline with a higher octane rating is more resistant to knocking and pinging than a lower-octane fuel. So why doesn’t everyone just use high-octane gasoline? Because it is more expensive, and there is no advantage whatsoever in using premium gasoline in a car that doesn’t specifically require it. At one time, only premium gasoline included additives that prevent fuel-injector clogging; now, all grades are basically the same in this regard.
If your car requires high-octane gasoline and you habitually use regular gas because the engine exhibits no sign of knock, you’re outsmarting yourself. Most modern, computer-controlled engines include a knock sensor that detects knock and retards the ignition timing, causing the spark plugs to fire slightly later in the cycle. This typically prevents abnormal combustion and knock, which allows vehicles specified for premium fuel to run on lower-grade gasoline if it is all that’s available. While this removes the immediate hazard, it’s a bad idea to make a habit of running a vehicle on gasoline of lower-than-recommended octane. Retarding the spark causes a richer fuel/air mixture, which decreases fuel economy, increases emissions, causes the engine to run hotter, and reduces the longevity of both the engine itself and the catalytic converter. The money you save by pumping low-grade fuel into a car that demands higher octane is lost anyway, in decreased fuel economy and possibly gradual damage.
Your vehicle’s owner’s manual usually recommends an octane rating in terms of an Antiknock Index (AKI), which also is posted on gasoline pumps. The AKI is the average of two ratings determined in a laboratory: the Research Octane Number (RON), which corresponds with low-speed, mild-knocking conditions, and the Motor Octane Number (MON), which covers high-speed, high-temperature knocking conditions and part-throttle operation.
In general, three grades of gasoline are available in the United States: regular (AKI = 87), midgrade (AKI = 89) and premium (AKI = 91 to 94). The posted gasoline AKIs are lower in the Rocky Mountain states because less octane is needed at higher altitudes. Motorists whose cars require 91 octane fuel may find themselves at filling stations that offer only 89 and 93 octane, but nothing in between. In these cases, the options are to pay more for the 93 octane or to fill the tank halfway with 93 and the rest with 89. The resulting gasoline mixture, just like the average of their two AKI numbers, will equal 91 octane.
Premium fuel is mostly required by engines with high compression ratios and/or turbochargers or superchargers, for reasons explained in What Causes Knocking and Pinging.
Aftermarket Octane Boosters
Like higher-octane fuel from the pump, aftermarket octane booster additives you can buy in a store will not improve performance if you use the correct gasoline grade to begin with. It likely will benefit only an older car with a high-compression engine. There are three basic types of octane boosters:
Aromatic hydrocarbons, such as oxylene and toluene, which provide only a marginal octane increase.
Alcohols, such as methanol or ethanol, which are the most common and provide only a bit more boost.
Metallic octane boosters that contain methyl-cyclopentadienyl manganese (MMT), which are by far the most effective.
How Gasoline Octane Is Determined
A gasoline blend’s octane rating is determined by combusting it in a one-cylinder test engine and comparing its antiknock performance to that of standard, measurable reference fuels. The test engine allows the administrator to vary the compression and fuel/air mixture ratios — two factors that affect knock — with the goal of inducing a standard knock intensity, as measured by a knock meter.
All gasoline is a mixture of different hydrocarbons (hydrogen and carbon molecules of various configurations) ending in “ane,” as in hexane, nonane and dodecane. Two such hydrocarbons represent each end of the octane scale: Iso-octane has an octane rating of 100 and heptane a rating of 0. The technicians run the same engine on a blend of these two fuels and vary the ratio of each to the other until the knock intensity matches that of the gasoline under test. The percentage of iso-octane in that mixture — say, 93 percent iso-octane to 7 percent heptane — is the tested gasoline’s AKI rating: 93 octane.
How Gasoline Octane Is Controlled
Between 1923 and 1986, when leaded gas was sold in the United States, the accepted method of boosting octane ratings was to add tetraethyl lead (TEL) to gasoline. The sale of leaded gasoline in the United States is now prohibited because it contaminates the precious metals used in catalytic converters and it is considered harmful to people and the environment. Leaded gasoline is still used in less-developed parts of the world, because it’s cheaper to produce, and many of the older vehicles found in these countries require it for its additional lubrication properties.
Iso-octane would seem the perfect additive to vary gasoline octane ratings, but it is far too expensive. Refiners now use other metal-, alcohol- or hydrocarbon-based elements to vary octane in gasoline blends. The oxygenates added to create cleaner-burning reformulated gasoline (RFG), mainly methyl tertiary-butyl ether (MTBE) and ethanol, also boost octane. To learn more about reformulated gas and why it adds cost, see Oxygenates and Reformulated Gas.
01-25-2004, 12:30 AM
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holy long post. but perfect. i think, if i remember my chemistry, octane reduces the compressional detonation of the gasoline, so it burns quicker in less time when detonated by ol sparkie. the engineers who design these engines know best what is needed, so i'd suggest sticking by the owner's manual octane suggestion.
01-25-2004, 06:56 AM
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Oscar,
WOW, that was thorough! Please tell me you didn't go through the hassle to type that all out.
I was worried that I was only giving my car the bare minimum of what it needed (which is generally NOT how I treat my newest best friend), but it seems that perhaps a 91 octane rating at 4-7,000 ft elevation (which is where I typically drive) is equivalent to a slightly higher rating at sea-level. Is that misusing the information, or does that sound right? Thanks for the help.
WOW, that was thorough! Please tell me you didn't go through the hassle to type that all out.
I was worried that I was only giving my car the bare minimum of what it needed (which is generally NOT how I treat my newest best friend), but it seems that perhaps a 91 octane rating at 4-7,000 ft elevation (which is where I typically drive) is equivalent to a slightly higher rating at sea-level. Is that misusing the information, or does that sound right? Thanks for the help.
01-25-2004, 08:28 AM
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Oscayer Mayer that was a very informative post! Why does Cali get lower octane as well? And aren't you the one usually advocating using lower than recommended octane? Why the change of heart?
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01-25-2004, 10:45 AM
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>And aren't you the one usually advocating using lower than >recommended octane? Why the change of heart?
If you can't beat'em join'em, premium lovers will never change.
Premium lovers are passionate. They would simply curtail driving rather than switch grades.
Prejudice and preference aside, engineers, scientists and the federal government say there's little need for premium.
Today's engines designed for premium run fine on regular, too, their makers say, though power declines slightly.
The main advantage of premium-grade gas is that it allows automakers to advertise a few more horsepower by designing and tuning engines to take advantage of premium's anti-knock properties. But auto engineers generally agree that if you use regular in a premium engine, the power loss is so slight, most drivers can't tell.
If you can't beat'em join'em, premium lovers will never change.
Premium lovers are passionate. They would simply curtail driving rather than switch grades.
Prejudice and preference aside, engineers, scientists and the federal government say there's little need for premium.
Today's engines designed for premium run fine on regular, too, their makers say, though power declines slightly.
The main advantage of premium-grade gas is that it allows automakers to advertise a few more horsepower by designing and tuning engines to take advantage of premium's anti-knock properties. But auto engineers generally agree that if you use regular in a premium engine, the power loss is so slight, most drivers can't tell.
01-25-2004, 07:51 PM
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really interesting stuff... i've always been wondering about the relationship of octane versus whp in the Z... i know that the VQ was designed to handle, in stock form, up to 100 octane race gas. I've seen a local doing that at the track, and i've read about it here on this forum. Everyone who's run with 100 octane race gas has concluded that in fact they get a faster seat of the paints sensation from the car. But yes... seat of the paints proves nothing...
but this has lead me to wonder:
All these people on the forum who have dyno'd the car, some people have gotten 230 whp, some have gotten 250 hp STOCK. Now a 10% variance like this is not impossible, but statistically speaking, 10% variance in an engine production environment is QUITE high considering assembly lines only have a tolerance for aobut 2% (according mech. engineer friend who works at ford).
SO... could this variance in dyno whp be the result of some people using 91 octane gas, and others using 93/94 octane gas? Someone should do a dyno to test this theory (i would but it's too cold right now
).
but this has lead me to wonder:
All these people on the forum who have dyno'd the car, some people have gotten 230 whp, some have gotten 250 hp STOCK. Now a 10% variance like this is not impossible, but statistically speaking, 10% variance in an engine production environment is QUITE high considering assembly lines only have a tolerance for aobut 2% (according mech. engineer friend who works at ford).
SO... could this variance in dyno whp be the result of some people using 91 octane gas, and others using 93/94 octane gas? Someone should do a dyno to test this theory (i would but it's too cold right now
).
01-25-2004, 08:24 PM
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Can you say "plagiarism"?
I'm cool with posting info, but could you at least acknowledge other people's work? Perhaps I'm wrong and you did write the article?
http://www.omegamotors.com/enjoy/gas...soline_06.html
http://www.omegamotors.com/enjoy/gas...soline_06.html
Originally posted by oscarmayer00
A gasoline’s octane rating quantifies its resistance to knocking and pinging. These two sounds are caused by abnormal combustion, which robs power and can damage an engine. Knocking and pinging are basically the same thing; knocking is louder and represents a more serious condition. When they occur, it is during acceleration, though higher engine speeds tend to drown them out. Knocking sounds like someone repeatedly rapping the engine with a hammer, and the quieter pinging resembles marbles being shaken inside a tin can.
Many conditions in the engine itself can cause or promote combustion anomalies, but when all other factors are equal, gasoline with a higher octane rating is more resistant to knocking and pinging than a lower-octane fuel. So why doesn’t everyone just use high-octane gasoline? Because it is more expensive, and there is no advantage whatsoever in using premium gasoline in a car that doesn’t specifically require it. At one time, only premium gasoline included additives that prevent fuel-injector clogging; now, all grades are basically the same in this regard.
If your car requires high-octane gasoline and you habitually use regular gas because the engine exhibits no sign of knock, you’re outsmarting yourself. Most modern, computer-controlled engines include a knock sensor that detects knock and retards the ignition timing, causing the spark plugs to fire slightly later in the cycle. This typically prevents abnormal combustion and knock, which allows vehicles specified for premium fuel to run on lower-grade gasoline if it is all that’s available. While this removes the immediate hazard, it’s a bad idea to make a habit of running a vehicle on gasoline of lower-than-recommended octane. Retarding the spark causes a richer fuel/air mixture, which decreases fuel economy, increases emissions, causes the engine to run hotter, and reduces the longevity of both the engine itself and the catalytic converter. The money you save by pumping low-grade fuel into a car that demands higher octane is lost anyway, in decreased fuel economy and possibly gradual damage.
Your vehicle’s owner’s manual usually recommends an octane rating in terms of an Antiknock Index (AKI), which also is posted on gasoline pumps. The AKI is the average of two ratings determined in a laboratory: the Research Octane Number (RON), which corresponds with low-speed, mild-knocking conditions, and the Motor Octane Number (MON), which covers high-speed, high-temperature knocking conditions and part-throttle operation.
In general, three grades of gasoline are available in the United States: regular (AKI = 87), midgrade (AKI = 89) and premium (AKI = 91 to 94). The posted gasoline AKIs are lower in the Rocky Mountain states because less octane is needed at higher altitudes. Motorists whose cars require 91 octane fuel may find themselves at filling stations that offer only 89 and 93 octane, but nothing in between. In these cases, the options are to pay more for the 93 octane or to fill the tank halfway with 93 and the rest with 89. The resulting gasoline mixture, just like the average of their two AKI numbers, will equal 91 octane.
Premium fuel is mostly required by engines with high compression ratios and/or turbochargers or superchargers, for reasons explained in What Causes Knocking and Pinging.
Aftermarket Octane Boosters
Like higher-octane fuel from the pump, aftermarket octane booster additives you can buy in a store will not improve performance if you use the correct gasoline grade to begin with. It likely will benefit only an older car with a high-compression engine. There are three basic types of octane boosters:
Aromatic hydrocarbons, such as oxylene and toluene, which provide only a marginal octane increase.
Alcohols, such as methanol or ethanol, which are the most common and provide only a bit more boost.
Metallic octane boosters that contain methyl-cyclopentadienyl manganese (MMT), which are by far the most effective.
How Gasoline Octane Is Determined
A gasoline blend’s octane rating is determined by combusting it in a one-cylinder test engine and comparing its antiknock performance to that of standard, measurable reference fuels. The test engine allows the administrator to vary the compression and fuel/air mixture ratios — two factors that affect knock — with the goal of inducing a standard knock intensity, as measured by a knock meter.
All gasoline is a mixture of different hydrocarbons (hydrogen and carbon molecules of various configurations) ending in “ane,” as in hexane, nonane and dodecane. Two such hydrocarbons represent each end of the octane scale: Iso-octane has an octane rating of 100 and heptane a rating of 0. The technicians run the same engine on a blend of these two fuels and vary the ratio of each to the other until the knock intensity matches that of the gasoline under test. The percentage of iso-octane in that mixture — say, 93 percent iso-octane to 7 percent heptane — is the tested gasoline’s AKI rating: 93 octane.
How Gasoline Octane Is Controlled
Between 1923 and 1986, when leaded gas was sold in the United States, the accepted method of boosting octane ratings was to add tetraethyl lead (TEL) to gasoline. The sale of leaded gasoline in the United States is now prohibited because it contaminates the precious metals used in catalytic converters and it is considered harmful to people and the environment. Leaded gasoline is still used in less-developed parts of the world, because it’s cheaper to produce, and many of the older vehicles found in these countries require it for its additional lubrication properties.
Iso-octane would seem the perfect additive to vary gasoline octane ratings, but it is far too expensive. Refiners now use other metal-, alcohol- or hydrocarbon-based elements to vary octane in gasoline blends. The oxygenates added to create cleaner-burning reformulated gasoline (RFG), mainly methyl tertiary-butyl ether (MTBE) and ethanol, also boost octane. To learn more about reformulated gas and why it adds cost, see Oxygenates and Reformulated Gas.
A gasoline’s octane rating quantifies its resistance to knocking and pinging. These two sounds are caused by abnormal combustion, which robs power and can damage an engine. Knocking and pinging are basically the same thing; knocking is louder and represents a more serious condition. When they occur, it is during acceleration, though higher engine speeds tend to drown them out. Knocking sounds like someone repeatedly rapping the engine with a hammer, and the quieter pinging resembles marbles being shaken inside a tin can.
Many conditions in the engine itself can cause or promote combustion anomalies, but when all other factors are equal, gasoline with a higher octane rating is more resistant to knocking and pinging than a lower-octane fuel. So why doesn’t everyone just use high-octane gasoline? Because it is more expensive, and there is no advantage whatsoever in using premium gasoline in a car that doesn’t specifically require it. At one time, only premium gasoline included additives that prevent fuel-injector clogging; now, all grades are basically the same in this regard.
If your car requires high-octane gasoline and you habitually use regular gas because the engine exhibits no sign of knock, you’re outsmarting yourself. Most modern, computer-controlled engines include a knock sensor that detects knock and retards the ignition timing, causing the spark plugs to fire slightly later in the cycle. This typically prevents abnormal combustion and knock, which allows vehicles specified for premium fuel to run on lower-grade gasoline if it is all that’s available. While this removes the immediate hazard, it’s a bad idea to make a habit of running a vehicle on gasoline of lower-than-recommended octane. Retarding the spark causes a richer fuel/air mixture, which decreases fuel economy, increases emissions, causes the engine to run hotter, and reduces the longevity of both the engine itself and the catalytic converter. The money you save by pumping low-grade fuel into a car that demands higher octane is lost anyway, in decreased fuel economy and possibly gradual damage.
Your vehicle’s owner’s manual usually recommends an octane rating in terms of an Antiknock Index (AKI), which also is posted on gasoline pumps. The AKI is the average of two ratings determined in a laboratory: the Research Octane Number (RON), which corresponds with low-speed, mild-knocking conditions, and the Motor Octane Number (MON), which covers high-speed, high-temperature knocking conditions and part-throttle operation.
In general, three grades of gasoline are available in the United States: regular (AKI = 87), midgrade (AKI = 89) and premium (AKI = 91 to 94). The posted gasoline AKIs are lower in the Rocky Mountain states because less octane is needed at higher altitudes. Motorists whose cars require 91 octane fuel may find themselves at filling stations that offer only 89 and 93 octane, but nothing in between. In these cases, the options are to pay more for the 93 octane or to fill the tank halfway with 93 and the rest with 89. The resulting gasoline mixture, just like the average of their two AKI numbers, will equal 91 octane.
Premium fuel is mostly required by engines with high compression ratios and/or turbochargers or superchargers, for reasons explained in What Causes Knocking and Pinging.
Aftermarket Octane Boosters
Like higher-octane fuel from the pump, aftermarket octane booster additives you can buy in a store will not improve performance if you use the correct gasoline grade to begin with. It likely will benefit only an older car with a high-compression engine. There are three basic types of octane boosters:
Aromatic hydrocarbons, such as oxylene and toluene, which provide only a marginal octane increase.
Alcohols, such as methanol or ethanol, which are the most common and provide only a bit more boost.
Metallic octane boosters that contain methyl-cyclopentadienyl manganese (MMT), which are by far the most effective.
How Gasoline Octane Is Determined
A gasoline blend’s octane rating is determined by combusting it in a one-cylinder test engine and comparing its antiknock performance to that of standard, measurable reference fuels. The test engine allows the administrator to vary the compression and fuel/air mixture ratios — two factors that affect knock — with the goal of inducing a standard knock intensity, as measured by a knock meter.
All gasoline is a mixture of different hydrocarbons (hydrogen and carbon molecules of various configurations) ending in “ane,” as in hexane, nonane and dodecane. Two such hydrocarbons represent each end of the octane scale: Iso-octane has an octane rating of 100 and heptane a rating of 0. The technicians run the same engine on a blend of these two fuels and vary the ratio of each to the other until the knock intensity matches that of the gasoline under test. The percentage of iso-octane in that mixture — say, 93 percent iso-octane to 7 percent heptane — is the tested gasoline’s AKI rating: 93 octane.
How Gasoline Octane Is Controlled
Between 1923 and 1986, when leaded gas was sold in the United States, the accepted method of boosting octane ratings was to add tetraethyl lead (TEL) to gasoline. The sale of leaded gasoline in the United States is now prohibited because it contaminates the precious metals used in catalytic converters and it is considered harmful to people and the environment. Leaded gasoline is still used in less-developed parts of the world, because it’s cheaper to produce, and many of the older vehicles found in these countries require it for its additional lubrication properties.
Iso-octane would seem the perfect additive to vary gasoline octane ratings, but it is far too expensive. Refiners now use other metal-, alcohol- or hydrocarbon-based elements to vary octane in gasoline blends. The oxygenates added to create cleaner-burning reformulated gasoline (RFG), mainly methyl tertiary-butyl ether (MTBE) and ethanol, also boost octane. To learn more about reformulated gas and why it adds cost, see Oxygenates and Reformulated Gas.
01-27-2004, 06:56 PM
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From everything Ive read Oscar Meyer is correct.In one of the tests Ive read it was stated that for some unknown reason some of the cars performed consistantly worse on higher octane.Many people still believe that higher octane has more energy and burns with more force so to speak,while octane really does the reverse and retards the firing
01-28-2004, 05:35 AM
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Originally posted by rolman
From everything Ive read Oscar Meyer is correct.In one of the tests Ive read it was stated that for some unknown reason some of the cars performed consistantly worse on higher octane.Many people still believe that higher octane has more energy and burns with more force so to speak,while octane really does the reverse and retards the firing
From everything Ive read Oscar Meyer is correct.In one of the tests Ive read it was stated that for some unknown reason some of the cars performed consistantly worse on higher octane.Many people still believe that higher octane has more energy and burns with more force so to speak,while octane really does the reverse and retards the firing
01-28-2004, 12:53 PM
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Originally posted by Strife350z
really interesting stuff... i've always been wondering about the relationship of octane versus whp in the Z... i know that the VQ was designed to handle, in stock form, up to 100 octane race gas. I've seen a local doing that at the track, and i've read about it here on this forum. Everyone who's run with 100 octane race gas has concluded that in fact they get a faster seat of the paints sensation from the car. But yes... seat of the paints proves nothing...
but this has lead me to wonder:
All these people on the forum who have dyno'd the car, some people have gotten 230 whp, some have gotten 250 hp STOCK. Now a 10% variance like this is not impossible, but statistically speaking, 10% variance in an engine production environment is QUITE high considering assembly lines only have a tolerance for aobut 2% (according mech. engineer friend who works at ford).
SO... could this variance in dyno whp be the result of some people using 91 octane gas, and others using 93/94 octane gas? Someone should do a dyno to test this theory (i would but it's too cold right now).
really interesting stuff... i've always been wondering about the relationship of octane versus whp in the Z... i know that the VQ was designed to handle, in stock form, up to 100 octane race gas. I've seen a local doing that at the track, and i've read about it here on this forum. Everyone who's run with 100 octane race gas has concluded that in fact they get a faster seat of the paints sensation from the car. But yes... seat of the paints proves nothing...
but this has lead me to wonder:
All these people on the forum who have dyno'd the car, some people have gotten 230 whp, some have gotten 250 hp STOCK. Now a 10% variance like this is not impossible, but statistically speaking, 10% variance in an engine production environment is QUITE high considering assembly lines only have a tolerance for aobut 2% (according mech. engineer friend who works at ford).
SO... could this variance in dyno whp be the result of some people using 91 octane gas, and others using 93/94 octane gas? Someone should do a dyno to test this theory (i would but it's too cold right now
).
01-28-2004, 02:00 PM
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Ya know what cracks me up, are the people who run like 3 tanks of regular, then run a tank of premium. Like it's some sort of treat for their car or something. I've tried to explain this to my little ricer buddies, but they just don't get it. You need high octane, for high compression, so the gas doesn't ignite before the piston can fully compress the air fuel mixture. Thus causing knocking, pinging, etc... Personally, I only run premium in my Z, as I know it can lead to emissions problems over time. Learned that the hard way with my 300ZX, and I'm not about to chance it with my 350.
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