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Recently I started mixing Union Oil Racing Fuel (100 octane) with premium gas (91) 3:1 and Wow what a difference in the performance of the engine!! I calculated that this formulation 9 gallons of 91 to 3 gallons of 100 gives me around 93+ octane. Porsche recommends 93 octane and I can see why. The car runs much smoother on the freeways in 4th (4000rpm) and accelerates much better. I have been doing some reading of octane boosters, mixing fuels and adding toluene. I rally don't like octane boosters because of the additives and MTMB (sp?) used to raise the octane. At about $9 a bottle you get only about 0.3 to 0.5 of octane boost. I have been using racing fuel mixture for about 2 months now and can really tell the difference. I also have been reading about adding toluene to the 91 premium gas. Toluene is present in gasoline and is used by the gas companies to boost octane at the refinery. I figured that if I add 1 gallon of toluene (114 octane) to 11 gallons of 91 premium, I will get around 93 octane. I included a internet site which is a FAQ about toluene. Just so happens that I have a station about 3 miles away that carries racing fuel so I haven't tried the the toluene yet. But it makes since. If any of you have not tried using 93+ octane as recommended by Porsche, you just gotta try it, it really makes a difference. I am told that the computer in the car will adjust for reduced octane by retarding the timing a little, and this can only affect performance. If you are looking for a station near you that may carry racing fuel see the SUNOCO site, they list station accross the US that carry racing fuel. Her is the site for the toluene questions. ( If you want to do y0u own calculations to get octane rating desired use this formula. Figue out which octane you want say 93. Multiply 93 by how many gallons you usually fill up with say 12. 93x12=1116 total octane. Just work back using the 100 octane racing fuel and figure out how many gallons of premium and racing fuel needed to equal 1116. I not a math wizard so this is how I did it.


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Yes I have used Toluene and Xylene but not on the Porsche. I have been doing the race fuel mixture for racing only. When i did use toluene it was on an SRT-4. Felt good and had no adverse effects. Then again it wasn't a Porsche. Has anyone tried Xylene or Toluene on a Porsche?

If it works in a Chevy it works in a Porsche. The engine in your Porsche is nothing special and is just another internal combustion engine. As a matter of fact, if you put gas in your Porsche now, chances are, you are using Toluene.

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If it works in a Chevy it works in a Porsche. The engine in your Porsche is nothing special and is just another internal combustion engine. As a matter of fact, if you put gas in your Porsche now, chances are, you are using Toluene.

+1...toluene is a typical additive in most fuels to "manage" octane rating.

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Why not just go to the station and buy some 93 octane? :) :) Guess you gotta move out of the west coast to get that though!!! :(

I've been thinking of putting some CAM2 (I think it is either 100 or 104 octane) in my car during the winter to protect it from the cooler weather and the extra boost I see during the winter.

It is interesting to watch the price of gas go down so dramatically and the price of race fuel stay the same!!!

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Just to clarify, In California we only have 91 octane premium as standard. I have never seen anything higher in California other than the racing fuel (100 octane). I haven't used the toluene yet since I have a station with 100 octane racing fuel so close, but if I go on a trip, I might take a gallon or two of toluene with me to boost the octane. I run it in a 04 C4S, no modiifications other than a FabSpeed exhaust. I don't track the car since it has a tiptronic and I really do not want to run it that hard. Other sites that I visited on the internet talk about the dangers of handling toluene. So I would suggest using chemical gloves with plenty of ventilation and remember use a long funnel. I also read on a BMW blog that when they tested the M-5 they put toluene in the tank to boost the octane to recommended levels. I agree on the price of racing fuel, it has not come down one penny, my station charges 8.99/gal!! I guess because it is the only station within 15 miles that carries the racing fuel and they can get it. Still cheaper than booster at $9-12 a bottle

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I have been mixing 100 octane and 91 Octane for years in my 996. The engine does run smoother, and has better power than just 91. I use a 1:4 ratio of 100 and 91.

Hi...Where do you buy 100 octane fuel? I live in Millbrae.

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Sherwin Williams sells xylene by the 5 gal. pales. When gas was $4 / gal, I remember shelling out well over $10/gal for that stuff. With chemicals in the dolldrums nowadays (I sell them for a living) I figure prices should be much better.

FYI: Xylene has an octane rating of 117, so 1:12 ratio gives you a 2 point increase over 91 octane pump gas.

Attached is my blend values calc sheet. This allows you to see how much you're getting ripped of by buying race gas instead of toluene / xylene.



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