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Discussion Starter · #1 ·
I've been researching adding toluene to my gas to get to 93 octane. Has anyone done this with their porsche on a regular basis?

The Mixture:
The 987.2 has a 16.9 gal tank I generally add 15 gallons when I fill up. In So-Cal we have 91 octane. If I put in 1.5 gal of toluene (rated at 114 octane) to 14 gal of 91. (14 * 91) + (1.5 * 114) / 15.5 = 93.2 Octane

Pricing:
91 Octane is currently $3.09/gal at my preferred station and toluene is $8.68/gal, cost for 93 octane is: $3.63/gal. Racing fuel at 100 octane is $9.49 since I need 4gal of 100 to 11 gal of 91 to get the same 93 the pricing is: $4.79/gal. I'm looking for better pricing on the toluene $8.68/gal for a 5gal drum at Sherwin & Williams paint supply.

I'll be doing a test run this weekend on the butt-dyno to see what happens.
 

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You will probably need a pretty sensitive butt-dyno to detect anything other than a placebo effect. ;)

A while back, Scott at Softronic mentioned that going from 93 Oct to 100 Oct, w/ his tuning capable of taking advantage of 100 Oct, would only add something like 3-4 HP at the most, as I recall.
 

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Be careful. While toluene has an octane rating of 114, there are downsides to mixing it with your gasoline:

- Potentially explosive/flammable
- Can cause damage to fuel pump impeller
- Possible damage to throttle body
- It's bad for your health

Have you considered looking for a gas station in your area that offers 104-105 octane race gas?
 

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i think they sell 1 pint cans of booster....but unless you have an ECM tune i dont think it will help
 

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Be careful. While toluene has an octane rating of 114, there are downsides to mixing it with your gasoline:

- Potentially explosive/flammable
- Can cause damage to fuel pump impeller
- Possible damage to throttle body
- It's bad for your health
Last time I tried burning gas, it's pretty explosive and flammable also. I wouldn't try breathing or drinking it either, so toluene can't be any worse. Toluene is a minor component is gas, AFAIK, and it's not carcinogenic, like benzene, another octane booster.
 

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Last time I tried burning gas, it's pretty explosive and flammable also. I wouldn't try breathing or drinking it either, so toluene can't be any worse. Toluene is a minor component is gas, AFAIK, and it's not carcinogenic, like benzene, another octane booster.
It's a lot easier to get exposed to toluene than regular gasoline. At least gasoline is required to be transported in specific containers by law, which limits exposure to flammable vapors.

Regardless, I don't think a recommendation to be careful around toluene is THAT unreasonable, is it? If you don't know what you're doing, you'll end up hurting either yourself or your car's engine.
 

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I'll preface my comments by stating that I have spent 40 years in the oil business (OK I'm old), but I'm not a chemical engineer.

The principle component in gasoline is naphtha, other components are added to meet various specs; octane, boiling range, flash point, freeze point, viscosity, etc. Adding too much of any one component will change the overall specification to a product that will not perform as it is supposed to, which may lead to serious consequences for your engine.

Just adding toluene may increase the octane rating but lower the flash point and therefore cause the engine to misfire; octane is not, in and of itself, a panacea.

The composition of the gasoline (molecules) MUST remain with the specification range or the law of unintended consequences will be the result.
 

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Discussion Starter · #8 ·
Gasoline (petrol)
Flashpoint: −40 °C (−40 °F)
Autoignition temperature: 246 °C (475 °F)
Energy: 47.30MJ/kg
Viscosity: 0.64

Toluene
Flashpoint: 4 °C (39 °F)
Autoignition temperature: 422C (792F)
Energy: 40.589MJ/kg
Viscosity: 0.68

Toluene due to having a higher flash point and autoignition temperature is why it increases the possible compression ratio... It does have slightly less energy.
 

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I have played with it extensively in my Audi. It is a cost effective way to increase Octane. I am quite confident that your car will benefit from it as the stock ECU is made to run on 93 octane. That is why west coasters really struggle to show the same improvements from ECU flashes as for example the guys in UK.

My preference has always been a gas station that sells 93 or 94 Octane. But the closest one I have found is 30 miles away!

I do not know how much Toulene is too much. Adding it to the gas tank will also be tricky, it will ruin your pain if spilled and left there.

I am very interested to see what your results are. Though the most interesting test would be to dyno your car on 91 octane and then back on 94.

Do you already have ECU flash? If not, maybe experiment after you get your car chipped.

Finally IATs have also high impact on timing. I become much more concerned with higher octane gas when air temps get above 70 deg. F. That usually transaltes to 90 deg, F plus IATs. In LA, that is amlost every day.

Please keep us informed. Very curious how you do!
 

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I am a chemical engineer. As long as the contents of your tank are well-mixed, it will be fine. Toluene is safer than benzene and is no worse than most of what's in gasoline in terms of flamability, toxicity, etc. Toluene and similar compounds used to be more common in gasoline as they increase the octane rating. More recently, branched alkanes and oxygenates have been more popular because they contain more hydrogen per carbon atom and thus lead to lower CO2 emissions, because the oxygenates often come from agricultural products and are heavily subsidized, and because of fears of health concerns with benzene-related molecules.

In any event, go for it.
 

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The base file that you have will Substantially gain from a higher octane. All I will say is add a few points to it and then drive. The 91 oct flashes by Softronic have the most to gain by a higher octane.
 

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I am a chemical engineer. As long as the contents of your tank are well-mixed, it will be fine. Toluene is safer than benzene and is no worse than most of what's in gasoline in terms of flamability, toxicity, etc. Toluene and similar compounds used to be more common in gasoline as they increase the octane rating. More recently, branched alkanes and oxygenates have been more popular because they contain more hydrogen per carbon atom and thus lead to lower CO2 emissions, because the oxygenates often come from agricultural products and are heavily subsidized, and because of fears of health concerns with benzene-related molecules.

In any event, go for it.
Although it's been about 12 years since I worked refineries (mech e), in the '90's toluene was introduced in greater amounts, in double digit percentages, to avgas to be a partial substitute for lead. I think they still do it.

I would check to make sure the quality of the toluene that one buys at the paint store is consistent with fuel grade toluene. Never know what may be added or how quality is controlled (as opposed to all those gas stations with crack quality control:hilarious:). Getting a WHMIS sheet from the manufacturer may be a good initial indication.

As far as benzene is concerned, last time I looked, we had over a million gallons of the stuff where I now work. And you don't want to be exposed to that too long! All of that system is closed with refrigeration for vapour recovery, etc.
 

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My old race car was an MGB with a 14:1 compression ratio. When they began reducing octane I had a problem finding fuel. I tried some 100/115 green avgas which worked but later started running a blend of toluene, about 15%, this worked and I had no issues. The company I worked for bought this by the tank truck load for use as paint thinnerso my costs were low.
 

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There is one performance benefit that you guys failed to mention. Performane due to weight reduction. I'm speaking of course about that reduction in weight caused by the wad of cash that's no longer in your wallet. That's got to make your car go faster, no.....? ;)

If it were me, I'd find a source of 100 octane gasoline and blend it with 91 octane. Additives rarely work as promised.
 

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Ohh Gator.

Toulene works great. In addition to raising your octane it will keep your engine nice and clean.

The question is not does it raise Octane - that is well proven and gas companies use it for that exact purpose in the gas that many here use and used daily. We are not talking about a 250 ml. bottle. We are talking 20% mixture!

Please read here: Clickie

"Toluene, an aromatic circular hydrocarbon chain, is a regular component of pump gas and is available in various grades at chemical supply stores. Premium street gasoline carries roughly 3- to 5% toluene, which partially helps octane characteristics. Unocal's 100-octane race gas has almost 25% toluene."

Now, what we are discussing is - how safe is it for our cars at 20% mixture. Is it like Ethanol, that our cars can tolerate at 10% but at 85% things break?

BTW, how closely related are Toulene and Ethanol?

Tomasz
 

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Ohh Gator.

Toulene works great. In addition to raising your octane it will keep your engine nice and clean.
I couldn't resist.... :)

The question is not does it raise Octane - that is well proven and gas companies use it for that exact purpose in the gas that many here use and used daily. We are not talking about a 250 ml. bottle. We are talking 20% mixture!

Please read here: Clickie

Now, what we are discussing is - how safe is it for our cars at 20% mixture. Is it like Ethanol, that our cars can tolerate at 10% but at 85% things break?

BTW, how closely related are Toulene and Ethanol?

Tomasz
I don't think they are at all related. But I would be concerned about the possible side effects. OK, so lets say it raises octane. That may be, and as such it may allow the DME to use a more aggressive timing map which could result in more power. But, is that small increase in power coming at the cost of your gas tank? Your fuel pump? Your fuel lines? The injectors? How is it effecting your catalytic converter and/or the atmosphere? Like GilFrank said, gasoline is a very complex mixture. I don't pretend to understand the science. That's why I would feel safer mixing 100 octane race fuel with 91 octane pump fuel than I would about pouring paint thinner into my gas tank.
 

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Uh, yeah... This stuff isn't going into my Porsche:

Toluene can be used as an octane booster in gasoline fuels used in internal combustion engines. Toluene at 86% by volume fueled all the turbo Formula 1 teams in the 1980s, first pioneered by the Honda team. The remaining 14% was a "filler" of n-heptane, to reduce the octane to meet Formula 1 fuel restrictions. Toluene at 100% can be used as a fuel for both two-stroke and four-stroke engines; however, due to the density of the fuel and other factors, the fuel does not vaporize easily unless preheated to 70 degrees Celsius (Honda accomplished this in their Formula 1 cars by routing the fuel lines through the muffler system to heat the fuel). Toluene also poses similar problems as alcohol fuels, as it eats through standard rubber fuel lines and has no lubricating properties as standard gasoline does, which can break down fuel pumps and cause upper cylinder bore wear.

In Australia, toluene has been found to have been illegally combined with petrol in fuel outlets for sale as standard vehicular fuel. Toluene attracts no fuel excise, while other fuels are taxed at over 40%, so fuel suppliers are able to profit from substituting the cheaper toluene for petrol. This substitution is likely to affect engine performance and result in additional wear and tear. The extent of toluene substitution has not been determined.
 

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Ohh Gator.

BTW, how closely related are Toulene and Ethanol?

Tomasz
Well, they're both organic molecules, other than that, not at all. Toluene is benzene with CH3 substituted for one of the hydrogens. Ethanol is well an alcohol, C2H5OH; as we all can probably attest, it is water soluble, toluene is not. The oxygen in ethanol can make it corrosive, that's one of the reasons that unless your car was modified to run on E85 you can have problems with too much ethanol. I've never heard of any problems with too much toluene in gasoline.

That's it for today's and probably this year's chemistry lesson.
 

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I couldn't resist.... :)
Like GilFrank said, gasoline is a very complex mixture.
Well, maybe not about the chemistry lesson.

They don't use complex mixtures by design, but only because it is way too expensive to purify, and refine crude oil down to pure compounds, or even make the same pure compounds from different crudes which vary widely. The oil industry really does not care what compounds are in the gasoline as long as it meets certain specs like octane, vapor pressure, and contents of impurities such as sulfur, metals, phosphorus, etc. They would very much like to do a crude separation of the feedstock and sell that, which is why kerosene, jet fuel, home heating oil, etc. cost less (excluding taxes) than gasoline which requires many additional refining steps (cracking, reforming, alkylation, etc.) to get the right properties, if not always the same chemical makeup. It's also why "light-sweet crude" is more valuable than "heavy crude" - it requires fewer refining steps before it can be sold. Toluene and similar molecules are a product of the reforming step that boost octane ratings; as it requires an additional refining step, it increases cost which is why you pay more for higher octane ratings. Excluding taxes, pure toluene is far more expensive than any kind of gasoline because the purification step (distillation) is very energy intensive. No refiner would ever boost octane by putting pure toluene into the gas just because it is way too expensive.

As for damaging fuel lines etc., well I doubt it, but conceivably if you put enough into your gas then you could change the solvation properties of the fuel which has the remote possibility of begining to dissolve rubber and plastic parts. As for lubrication, you don't rely on fuels to lubricate and the viscosity of toluene is similar to everything else in gasoline except for ethanol which has a much higher viscosity.
 

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Discussion Starter · #20 ·
From what I've read around the web the lubrication factor has been my biggest concern. I even found this on one site:
MAKE YOUR OWN OCTANE BOOST
How to make your own octane booster (this is the basic formula of one of the popular octane booster products). To make eight 16 ounce bottles (128 oz = 1 gal):

100 oz of toluene for octane boost
25 oz of mineral spirits (cleaning agent)
3 oz of transmission fluid (lubricating agent)

This product is advertised as "octane booster with cleaning agent *and* lubricating agent!". Diesel fuel or kerosene can be substituted for mineral spirits and light turbine oil can be substituted for transmission fluid. Color can be added with petroleum dyes.
Adding the ATF seamed crazy to me, also it seams like your now burning dirty gas more likely to smoke and damage O2 Sensors and catalic converters... Not sure why you would need the mineral spirits either wouldn't the toluene act as a cleaning agent its self?
 
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