I only know what my dad told me and that is the higher octane gas means nothing unless you have modified your compression ratio...so it would be a big waste of $

 

GSR you need 93 or so it says on the gas cap and gauges and book. i drive my car hard sometimes and i can feel the differance than 87 and 93. i used 87 once and never again my baby only takes 93

 

LS takes 87 stock I think

 

well from ur name i take it you have a LS. so i would go with the middle gas. like 89-91. not regular or premium. the middle one. GSR's need premium

So wat? Are you tryin to say that LS's are mediocre??? That we don't own "Premium" quality vehicles cuz its not a GSR????

haha JUST KIDDING! Couldnt resist. I usually run 89-91 on my LS but then again here in California, 91 is premium!

 

LS does take 87 and is made for 87, however i have an LS and use 93 because i advanced my timing. 87 would run HORRIBLY on advanced timing.

 

guys it simple. octane rating has absolutly nothing to do with an increase in performance. nothing. the only thing a higher octane will do is prevent against detonation. and if you only have an ls and have done nothing to bump up your compression, than all you need is 87. using anything higher will not aid in any performance whatsoever. and 87 is perfectly fine for you to have no troubles with detonation.

 

From what I understand, the only differences in octane of gasoline are:

1. the price

2. How far it can be compressed w/o blowing up w/o a spark. (The higher the octane, the more it can be compressed without exploding)

What this means is if you have a LS and it only compresses the mixture so far, there is no need for the higher octane gas. If your engine was compressing more and the gas mixture was exploding before the piston reach tdc, then you would want to upgrade to higher octane...I believe your engine would experience detonation if you were using to low an octane...If I am wrong, someone correct me because I want to knwo about this too.

 

it looks like by the time I had that typed and posted hootb18 already gave the same answer...

 

GSR's don't nessecarily "need" premium gas. There is a knock sensor on the engine that retards the timing. Ofcourse this causes a loss in HP.

 

http://www.team-integra.net/forum/display_topic_threads.asp?ForumID=10&TopicID=13858&PagePosition=1&ThreadPage=2

My first comment: The search function , when used more often here, can dispense with repeat posting of a topic, whether it be about a CAI & whistling after install or hydrolock, or exhaust loudness from a Greddy EVO or APex N1 exhaust, or octane rating. I believe www.howstuffworks.com has a nice explanation of octane rating as well if you haven't looked there.

This is a must read for all beginners who cling to the erroneous notions of the purpose for higher octane rated fuels, in terms of making power:

http://speedarticles.com/auto_racing_article-46.html

if you have basic bolt-ons and do not experience knocking then it's pointless to go to a higher octane rated fuel than the one recommended in your owner's manual.

For those who are too lazy to do a search here, these were my replies to the link provided above regarding this topic.

Remember, if you go to a higher octane it slows the burn and therefore if you didn't need to slow the burn for the reasons I listed below to prevent detonation, then you are reducing your burn efficiency (fuel economy and emissions).

Remember also that our small displacement engines with intentionally more compact combustion chambers by design than the old domestic V8 chambers depend on the fastest burn rate allowable (lean fast burn theory) to get our power, emissions, and fuel economy.

Don't be the uneducated teg driver wearing the dunce cap on the block...learn WHY before you do something.:

I don't use high octane pump gas for power. I use it to prevent detonation in an engine that has 12:1 static CR. Higher octane just slows the burn process down. If you use it because you think it is for power, then indeed you are fooling yourself.

Some car models require you use higher octane fuel (EVAP system reasons). Check your owner's manual.

As far as I know, there is no car that purely combusts without incomplete burn byproducts. If you know of one, let me know.

Use higher octane for the intention it was designed for: less detonation...not for making power.




Quote: Michael Delaney on Oct/13/02
Quote: Laserguided on Oct/12/02
This is my experience with high octane. As far as that 94 octane is concerned, I used that stuff for a while thinking it was good. Then I came to the realization that I was just fooling myself and that my car was performing poorly especially at low rpms. I switched back to regular (yes, the cheap 87.5) and got way more power and eliminated that dip at low rpms. I would have reason to believe since all gasoline has pretty much the same heat value, that my low power on high octane was due to inefficient burning. That unburnt fuel has to go somewhere... I'm sure it wasn't as bad as if I were using 103 octane but there probably was some detrimental effect.

For everyone out there, the key is to use as low an octane value as you can. You'll burn more fuel that way. Higher octane is stunting your engines!



as was stated before, you use high octane to prevent knocking/detonation.

Many situations would warrant it. I stated mine: high CR.

other situations?:

- advance ignition timing beyond stock

- big cylinder bores

- running with consistently higher coolant temps.

- running with leaner air fuel ratios

- dry humidity areas

- being closer to sea level

- during high barometric pressures

I got a PM asking me what octane to run to prevent cat damage...people misunderstood that I was talking about octane boost with it's impurities could corrode and plug the honeycombs in a cat. High octane leaded racing fuel would damage your cat...but for the usual high octane unleaded pump gas that we see, no cat damage.

hope that cleared up the whole high octane and cat discussion as well as why you use high octane gas...it's not to make hp.

thanks.

 

Thanks for all the informative replies. Sorry- I'll search next time. Looks like I'll stay with the good 'ol 87.

 

here is some info on using aviation gasoline at the track vs. unleaded racing gasoline....

http://www.dragracingpinoy.com/tech_avgas.html

I am going to attempt to address the controversy of aviation gasoline verses racing gasoline for use in race cars. Some racers use aviation gasoline which is fine for some applications but does have shortcomings.

Avgas 100/130: this product that can be used in some automotive engines. It has both research and motor octane numbers slightly over 100. Avgas 100/130 is green in color, contains four grams of lead per gallon, and is becoming harder to find.

Avgas 100 LL: the LL stands for "low-lead" which means two grams per gallon, low compared to the avgas 100/130 that it was designed to replace. It has research and motor octane numbers very similar to the 100/130 product previously discussed. The color is blue. This product sometimes has a high level of aromatics which can contribute to lazy throttle response and dissatisfaction of the consumer.

Avgas 115/145: this product was developed for high performance piston aircraft engines used in world war II and in the Korean war. It is very hard to find anymore due to lack of demand although it is of very high octane quality. The color is purple.


...When the word "avgas" is used, it will refer to avgas 100/130 or 100 LL.

Avgas is less dense than most racing gasolines. Instead of weighing about 6.1 to 6.3 pounds per gallon like racing gasoline, it weighs 5.8 to 5.9 pounds per gallon. The racer must compensate for this by changing to richer (larger) jets in the carburetor when changing from racing gasoline to avgas.

The other major difference is octane quality. Avgas is short on octane compared to most racing gasolines. Many racing engines with "quick" spark advance curves or with no centrifugal advance have more spark advance at low rpm than avgas and some racing gasolines can handle. The result is detonation, especially during caution periods in circle track racing because all of the spark advance is "in", rpm is low, and part throttle air fuel ratios are too lean for the operating conditions. If the driver does not "work" the throttle back and forth, pistons can be "burned" which melts away part of the aluminum piston material. Inadequate octane quality is one of the quickest ways to destroy an engine. Pistons can be severely damaged during one acceleration where detonation is present and the racer may not know what is happening until it is too late.

For maximum performance and power from a racing engine, racing gasoline will normally provide better performance than avgas.

Avgas can be a good gasoline for some applications, but since most racers do not know the octane requirement of their engines, they would be better off with a "real" racing gasoline that will give them the overall resistance to detonation that they need to protect their investment. If someone has spent from $15,000 to $50,000 or more on their racing engine, it is foolish to cut corners on gasoline be sure you have a gasoline with adequate octane quality.

 

yea, but the only difference between 87 than 89+ is the miles per gallon u will get. i run 89 on my ls and i usually get 300-320 miles for the whole 11 gallon tank (i think theres 13 gallon altogether). if u run 87, im pretty sure u wont even get 300 for 11 gallons.....
the only difference between the 89-91-93 is the detenation...thats it!

 

WomBadtz: Why are you incorrect in your statement that you will get higher fuel economy with a higher octane fuel than you need?:

Higher octane rating will slow the burn process down. Your basic Japanese pentroof combustion chamber engine likes fast burn and fast flame speeds to help it completely burn all of the air fuel mix in the chamber.

you slow that flame and burn speed down by going to a higher octane than you need and you basically shoot yourself in the foot. A slower burn than what is expected without preventing knock will lead to incomplete burning of the air fuel mix. Incomplete burn means wasting fuel that just sits unburnt in your chamber or poorer fuel economy...this also leads to higher emissions (worst smog test).

follow the octane rating recommended UNLESS you hear knocking or one of the things on the list I provided is true for your modifications or where you live...eg. higher static CR or bigger bore or more spark advance above stock.


here is a quick look at what qualities of fuel racing teams look at:

The four most important properties of racing gasoline...

Listed below are the four basic qualities of fuels. As in everything there are trade-offs. You can't make a racing fuel that has the best of everything, but you can produce one that will give your engine the most power. This is why VP produces different fuel for different applications. The key to getting the best racing gasoline is not neccesarily buying the fuel with the highest octane but getting the one that is best suited to your engine. Octane is the rating of fuel's ability to resist detonation and/or preignition.

OCTANE

is rated in Research Octane Numbers (RoN), Motor Octane Numbers (MoN), and Pump Octane Numbers (R+M/2). Pump Octane numbers are what you see on the yellow decal on the pumps at the gas stations and represents an average of the two. VP uses MoN because this test method is more relevant to racing. Most other companies advertise RoN because it is higher and easier to come by. Don't by fooled by high RoN numbers or an average. MoN's are the most important for a racing application. However, the ability of the fuel to resist preignition is more than just a function of octane.

BURNING SPEED

is the speed at which a fuel releases its energy. In a high speed internal combustion engine there is very little time (real time - not crank rotation) for the fuel to release its energy. Peak cylinder pressure should occur around 20 degrees ATDC. If the fuel is still burning after this, it is not contributing to peak cylinder pressure, which is what the rear wheels see.

ENERGY VALUE

is an expression of the potential energy in the fuel. The energy value is measured in BTU's per pound, not per gallon. This difference is important as the air fuel ratio is in weight not volume. Remember, this is potential energy value of the fuel, and this difference will show up at any compression ratio or engine speed.

COOLING EFFECT

of the fuel is related to the heat of vaporization. The higher thhe heat of vaporization the better its effect on cooling the intake mixture. This is of some benefit in a 4-stroke engine, but can be a big gain in 2-stroke engines.





Quote: Rick O'Donnell
In many high-performance situations, riders clamor for higher octane fuels, thinking this will give them additional horsepower and, thus, an advantage over the competition.

But this is not the case -

adding higher-octane race fuel to your (car or) motorcycle may actually produce less horsepower. Here's why:

Octane, an arbitrary number which is calculated as the average the Research Octane Number (RoN) and the Motor Octane Number (MoN), and is only an indication of a fuel's sensitivity to knock, which is typically pressure-induced self-ignition. (Of these two ratings, MoN is more applicable to racing fuels as it is measured under high load and high speed conditions.)

Octane, as you can see, is not a measure of how much power - or, more correctly, specific energy - is contained in a fuel. And remember that leaded high-octane race fuels burn slower than most unleaded fuels, and may reduce performance in stock or lightly modified (cars or) motorcycles. A high octane rating itself, however, does not (necessarily) mean that the fuel is slow burning. Hence, it has no direct bearing on the power characteristics of the fuel.

The knock tendency (and hence, the Octane rating) of a fuel is a function of the amount of free radicals present in the fuel prior to ignition and can be reduced by the addition of tetra ethyl lead, aromatics and other additives.

Although some racing organizations still use maximum octane number as the discriminating factor for fuel legality, it is really not appropriate for racing purposes.

Instead one should look at the amount of energy (heat) released in the burning of a particular fuel. This is described by the specific energy of the fuel. This quantity describes the amount of power one can obtain from the fuel much more accurately. The specific energy of the fuel is the product of the lower heating value (LHV) of the fuel and molecular weight of air (MW) divided by the air-fuel ratio (AF):

Specific Energy = LHV*MW/AF

For example, for gasoline LHV= 43 MJ/kg and AF=14.6, while for methanol LHV= 21.1 MJ/kg (less "heat" than gasoline) and AF=6.46 (much richer jetting than gasoline). Using the above formula we see that methanol only has a 10% higher specific energy than gasoline! This means that the power increase obtained by running methanol, with no other changes except jetting, is only 10%. Comparing the specific energy of racing and premium pump gas you can see that there is not much, if any, difference. only alcohols (such as methanol or ethanol) have a slightly higher specific energy than racing or pump gas.

Other oxygen-bearing fuels, besides the alcohols and nitromethanes, such as the new EL fuel, will also produce slightly more power once the bike is rejetted.

However, at $15.00 to $20.00 at gallon for the fuel the reportedly minor (1 % - 2%) improvement is hardly worth the cost for the average racer.

The real advantage of racing gasolines comes from the fact that they will tolerate higher compression ratios (due to their higher octane rating) and thus indirectly will produce more power since you can now build an engine with a higher compression ratio. Also, alcohols burn cooler than gasoline, meaning even higher compression ratios are possible with them, for even more power.

The bottom line here is that, in a given engine, a fuel that doesn't knock will produce the same power as most expensive racing gasolines.

However, it sometimes happens that when you use another fuel, the engine suddenly seems to run better. The reasons for this are indirect:

First, the jetting may be more closely matched to the new fuel.

Secondly, the new fuel may improve the volumetric efficiency (that is, the "breathing") of the motor.

This happens as follows: Basically a fuel that quickly evaporates upon contact with the hot cylinder wall and piston crown will create additional pressure inside the cylinder, which will reduce the amount of fresh air/fuel mix taken in. This important-but often overlooked-factor is described by the amount of heat required to vaporize the fuel, described by the 'enthalpy of vaporization' (H), or 'heat of vaporization' of the fuel.

A high value of H will improve engine breathing, but the catch is that it leads to a different operating temperature within the engine. This is most important with two-strokes, which rely on the incoming fuel/air mix to do much of the cooling-even modern water-cooled two-strokes rely on incoming charge to cool the piston. For two-strokes a fuel that vaporizes, drawing a maximum amount of heat from the engine, is essential-the small variations in horsepower produced by different fuels is only of secondary concern.

Also important is the flame speed: Power is maximized the faster the fuel burns because the combustion pressure rises more quickly and can do more useful work on the piston. Flame speed is typically between 35 and 50 cm/sec. This is rather low compared to the speed of sound, at which pressure waves travel, or even the average piston speed. It is important to note that the flame propagation is greatly enhanced by turbulence (as in a motor with a squish band combustion chamber).

The most amazing thing about all this is that you can get the relevant information from mc racing gasoline manufacturers. Then, just look at the specification sheet to see what fuel suits you best: Hot running motors and 2-strokes should use fuels with a value of "H" that improves their cooling, while more power (and more heat) is obtained from fuels with a high specific energy.

By the way, pump gas has specific energies which are no better or worse than most racing gasolines. The power obtained from pump gas is therefore often identical to that of racing fuels, and the only reason to run racing fuels would be detonation problems, or, since racing fuels are often more consistent than pump gas - which racers call "chemical soup."

thanks

 

There is a lot of confusion about what the "octane number" on the gas pump means, what higher octane numbers really mean, and why some engines need or can take advantage of a higher octane fuel.

In a nutshell, the octane rating of a fuel is a measure of its ability to resist detonation, ping, pre-ignition, or knock.

Although purists will quibble, all of these terms can be described as an incorrectly-timed burning of the fuel/air mixture in the combustion chamber. Any motor fuel will spontaneously ignite under the right conditions - too much compression, hot spots from leftover carbon deposits, excessive boost, too much ignition advance, or a number of other causes can provide the source of ignition. When the flame front from this ignition event meets the one created by the spark plug, the result is sky-high cylinder pressures and a destructive shock wave that can shatter spark plug insulators, hammer rod bearings, break rings, or even put a hole in the piston. The octane number is a way to express the resistance of a fuel to this type of unwanted ignition.

Octane Myth #1 - Higher octane fuel is "more powerful" and "burns hotter"

The difference in total energy between high octane and regular gas is insignificant. In fact, race gas often has slightly less energy by weight than pump gas! High octane fuels are generally harder to ignite, and burn more slowly than ones with low octane. In some cases, an engine optimized to run on 87 octane gas will produce less power when fed racing gasoline due to the slower ignition and combustion characteristics of the high octane fuel.

The number we most often associate with octane is the "Anti-Knock Index", or the "Pump Octane" number. This rating is an average of two different measurements; the Motor Octane Number, and the Research Octane Number. Both of these measurements are taken using a special single cylinder test engine that has a variable compression ratio. The RoN measures the knock resistance of a fuel during low RPM, light load conditions, while the MoN is representative of high-speed, high load operation. As a result the MoN will always be lower than the RoN, but for our purposes the Motor Octane Number is more significant because it represents the way racing engines are operated.

Octane Myth #2 - Putting premium and/or race gas in my car will give me better performance

Engines are designed to run on gas with a certain AKI. Putting premium in a car that was designed to run on regular gas and doesn't knock is just throwing money away. If an engine doesn't knock on 87 octane gas, there is no advantage to using gasoline with a higher octane number. However, many engines with electronic controls have a knock sensor as part of their computer system. This sensor actually listens for knock, and can change the engine timing or even cut boost in a factory turbocharged car when it detects knock. Some anti-knock systems are sensitive enough that it's possible for them to reduce the performance of the engine without you ever hearing audible detonation. The bottom line - Read your owner's manual to determine the correct octane rating for your car and see if it can take advantage of premium fuel.

Obviously, an engine's octane requirement can change. Increasing the compression ratio, adding a turbo or supercharger, changing the air/fuel ratio, or advancing the ignition timing can all cause knock. Even without modifications, over time combustion chamber deposits build up and can lead to a need for higher octane fuel. The best way to determine what your engine needs is to listen to what it's telling you - Audible knock is a sign that damage to the engine is imminent! Better still are scan tools that can read the engine control computer's built-in knock sensor, or a stand-alone system that detects detonation. There's also the old fashioned but most accurate method is reading your plugs for signs of detonation. Whatever the case, it's worth the time to determine what your engine's real octane needs are. Too little, and you flirt with engine damage. Too much, and you're wasting money and quite possibly reducing performance.

Octane Myth #3 - My brother went to high school with this guy who had a Chevelle, and he went to the airport and filled it up with jet fuel. That gas was so high octane, it blew up the motor!

While aviation gasoline is indeed higher in octane than gas destined for street use, jet fuel is actually kerosene, which has an extremely low octane number. Jet engines have absolutely no use for high octane fuel, since their combustion process is totally different from that of gasoline engines. Putting jet fuel in an internal combustion engine is a sure way to destroy it immediately - not because the jet fuel is "too hot", but because it has no knock-suppressing capability. Incidentally, aviation gas also has a lot of tetraethyl lead in it. Despite the fact that the pump is labeled "100 Octane LL (low lead)" it still has more lead in it than the worst 1960's automotive gas. Running this through a car with an oxygen sensor or catalytic converter is sure death for those parts.

So what is the correct octane rating for your car? There's a delicate balance between many factors that determines how much knock suppression you need. Simply adding higher octane gasoline can keep your car from knocking, but it may mask other problems like an incorrect fuel/air ratio, ignition system trouble, or too much boost. Ideally, the car's state of tune should work in conjunction with the proper fuel, rather than using high octane gas as a band-aid to cover up some other problem. It's often cheaper in the long run to determine the root cause of knock instead of switching to a more expensive high-octane fuel. on the other hand, tuning an engine for maximum power will often demand the added knock resistance of higher octane gas. only by understanding how and why knock occurs, and the interaction between ignition, compression, fuel delivery, and the fuel itself can you reach the state of optimum performance.

 

I hope this clears up any more false ideas about what higher octane is for and that it's not for power.

 

90-91 dont have knock sensors right.. so what can we do? i suspect ill drive around with 87 and check the plugs for spots.. or just stick to 89. im at maybe 17-17.5btdc

 

What about octane boost as opposed to using more expensive higher octane fuels? I don't recommend it. They do a number on your valves : one of nicest places for carbon deposits to stick to is the impure deposits from octane boost that cling to the valves and valve seats. Here's a nice discussion on a popular octane boost, toluene.

Q: How did you discover using toluene?

A: Someone came across a web page that described various DIY home brew octane booster formulas. one of which used toluene as its main ingredient. As a Formula 1 racing fan of many years, I recalled that toluene was used extensively in the turbo era in the 1980s by all the Formula 1 teams. The 1.5 liter turbocharged engines ran as much as 5 bars of boost (73 psi) in qualifying and 4 bars (59 psi) in the actual race. Power output exceeded 1500bhp, which translates into 1000bhp/liter, an astronomical figure.

A motorsports journalist, Ian Bamsey, was able to obtain Honda's cooperation for his book "McLaren Honda Turbo, a Technical Appraisal". The book documents the key role that the toluene fuel played in allowing these tiny engines to run so much turbo boost without detonation. The term "rocket fuel" originated from the Formula 1 fraternity as an affectionate nickname to describe its devastating potency. Thus I concluded that I should focus my research on using toluene for my octane boosting project.

Individuals with good long term memory will recall that when unleaded gasoline was first introduced, only low octane grades were available. While it is not entirely clear that high octane super unleaded gas came about as a result of the advances in fuel technology in Formula 1, there is every reason to suspect that this is indeed the case, since many of the major oil companies were involved in the escalating race to develop increasingly potent racing fuel during this era.


Q: Why do you think toluene is better than other types of octane boosters?

A: Several reasons:

Mindful of the evil reputation of octane boosters in general, toluene is a very safe choice because it is one of the main octane boosters used by oil companies in producing ordinary gasoline of all grades. Thus if toluene is indeed harmful to your engine as feared, your engine would have disintegrated long, long ago since ordinary pump gasoline can contain as much as 50% aromatic hydrocarbons.

Toluene is a pure hydrocarbon (C7H8). i.e. it contains only hydrogen and carbon atoms. It belongs to a particular category of hydrocarbons called aromatic hydrocarbons. Complete combustion of toluene yields CO2 and H2O. This fact ensures that the entire emission control system such as the catalyst and oxygen sensor of your car is unaffected. There are no metallic compounds (lead, magnesium etc), no nitro compounds and no oxygen atoms in toluene. It is made up of exactly the same ingredients as ordinary gasoline. In fact it is one of the main ingredients of gasoline.

Toluene has a RoN octane rating of 121 and a MoN rating of 107, leading to a (R+M)/2 rating of 114. (R+M)/2 is how ordinary fuels are rated in the US. Note that toluene has a sensitivity rating of 121-107=14. This compares favorably with alcohols which have sensitivities in the 20-30 range. The more sensitive a fuel is the more its performance degrades under load. Toluene's low sensitivity means that it is an excellent fuel for a heavily loaded engine.

Toluene is denser than ordinary gasoline (0.87 g/mL vs. 0.72-0.74) and contains more energy per unit volume. Thus combustion of toluene leads to more energy being liberated and thus more power generated. This is in contrast to oxygenated octane boosters like ethanol or MTBE which contain less energy per unit volume compared to gasoline. The higher heating value of toluene also means that the exhaust gases contain more kinetic energy, which in turn means that there is more energy to drive turbocharger vanes. In practical terms this is experienced as a faster onset of turbo boost.

Chevron's published composition of 100 octane aviation fuel shows that toluene comprises up to 14% alone and is the predominant aromatic hydrocarbon. Unfortunately composition specifications for automotive gasoline is harder to pin down due to constantly changing requirements.

Chevron's web site also describes the problems of ethanol being used in gasoline.

MTBE was heavily touted as a clean additive several years ago, and became a key ingredient in reformulated gasoline that is sold in California. But recently new studies arose that showed that MTBE was far more toxic than previously imagined. Organizations such as oxybusters have formed around the country to eliminate the use of MTBE in gasoline and several states, including California have passed new laws to eventually outlaw MTBE.


Q: How much toluene should I use per tank of gas?

A: Octane ratings can be very easily calculated by simple averaging. For example, the tank of an Audi A4 1.8TQ is 15.6 gallons. Filling it with 14.6 gallons of 92 octane and 1 gallon of toluene (114 octane) will yield a fuel mix of:

(14.6 * 92) + (1 * 114) / 15.6 = 93.4

The Audi A4 1.8T is a good example of a car that has very high octane needs if it has been modified to produce more turbo boost. The base compression ratio of this car is a very high 9.5:1 and when an additional 1 bar (14.7 psi) of turbo boost is applied on top of it, the resulting effective compression ratio is way beyond what 92 or 93 octane fuel can ever hope to cope with. Most modified 1.8Ts running without octane enhancement are running with severely retarded ignition timing and boost.


Q: Will toluene damage my engine or other parts of my car?

A: A 5 or 10% increase in the aromatic content of gas will most likely be well within the refining specifications of gasoline defined by ASTM D4814, which specify an aromatic content of between 20% and 45%. What this means is that if the 92 octane gas that you started off with had an aromatic content of say 30% and you increased it by 10% to 40% you would still be left with a mix that meets the industry definition of gasoline. So the above question would amount to: "Will gasoline damage my engine or other parts of my car?"

Even in the unlikely event that the 92 octane gas has a aromatic content of 45% the resulting mix would still be within the bounds of gasoline sold in other countries.


Q: Isn't toluene an extremely toxic substance?

A: The common perception of toluene's toxicity far exceeds reality. Fortunately there is an ample body of information available that specifically addresses this question. Toluene is more toxic than gasoline but it is certainly not agent orange or cyanide.

US Environmental Protection Agency Chemical Summary

US Agency for Toxic Substances and Disease Registry (ATSDR)

National priority list of toxic substances
Note that the ATSDR also rates gasoline as a hazardous substance.

Mobil's spec sheet for toluene even goes as far as saying that "Based on available toxicological information, it has been determined that this product poses no significant health risk when used and handled properly."


Q: Isn't toluene an active ingredient of TNT (trinitrotoluene) and is thus deadly?

A: In the same way that cotton wool is the base ingredient of nitrocellulose (guncotton) which in turn is the main ingredient in modern smokeless gunpowder. Using this reasoning one could conclude that cotton wool is a deadly substance. This question reflects a poor understanding of basic chemistry but unfortunately it has been asked often enough.


Q: How much does toluene cost, and where can I buy some?

A: $10/gallon in a one gallon can at a hardware store, about $6/gallon in a 5 gallon can from a chemical supply or paint store, or $3/gallon in a 55 gallon drum from a chemical supply warehouse.


Q: Can I just dump in 100% toluene into the tank like the F1 racers? vroom vroom vroom

A: First of all, the F1 racers did not use 100% toluene, but 84%. The other 16% in their brew is n-heptane, which has an octane rating of zero. The reason for this strange combination is because the F1 rocket fuel was limited to the rules to being of 102 RoN octane. The n-heptane is "filler" to make the fuel comply with the rules.

Because toluene is such an effective anti knock fuel it also means that it is more difficult to ignite at low temperatures. The Formula 1 cars that ran on 84% toluene needed to have hot radiator air diverted to heat its fuel tank to 70C to assist its vaporization. Thus too strong a concentration of toluene will lead to poor cold start and running characteristics. I recommend that the concentration of toluene used to not exceed what the engine is capable of utilizing. i.e. Experiment with small increases in concentration until you can no longer detect an improvement.

Q: Ok, what is the catch?

A: It should be mentioned that in the US, efforts are underway to reduce the aromatic content of gasolines in general as a higher aromatic content leads to higher benzene emissions. Benzene is an extremely toxic substance. However it should also be noted that the proportions that is being discussed in this FAQ is relatively small and in the grand scheme of things is probably insignificant. Moreover, the industrial standard for defining gasoline composition allows plenty of leeway in aromatic content and the proportions present in US gas is already lower than most other countries. I therefore feel that the information provided here is useful to a performance minded car enthusiast while not being significantly detrimental to the environment.

 

Q: Can I just dump in 100% toluene into the tank like the F1 racers? vroom vroom vroom

HAHA...

Good info.

 

saves thread for the next time this question comes up

 

All I have to say is, damn. I wish I knew 1/1000 of what MD knows. Thanks for the info MD!

 

Lots of great information, this I am going to print off at work and read on my lunch break

 

Thank goodness, may a thread like this never show it's ugly face again. Added to "Common Topics" list for this forum so you can point any further threads like this one to here.

 

i was wondering if anyone has read this article from C&D Regular or Premium?
It's basically all the great info MD gave (albeit in an extremely condensed form) and a test to see exactly what different types of fuel does to different cars. Basically, the results say that if your car doesnt specifically ask for higher octane fuel, then you dont need it (unless the age of your engine becomes an issue).

 

All I have to say is, damn. I wish I knew 1/1000 of what MD knows. Thanks for the info MD!

i couldnt agree with you more, MD you truly are the Man