Two main ways to boost octane: (1) tetraethyl lead which is used in racing fuel and aviation gas, or (2) increased aromatic hydrocarbon content. Best way to use option one is to buy racing fuel by the barrel or make a trip to a friendly nearby airport. I've heard of people selling concentrated tetraethyl lead but I've not heard of anybody going that route. Once you acquire the racing/av fuel start mixing it in until the pinging stops. Option two: Gasoline is a mixture of lots of different hydrocarbons (xylene, toluene, etc.). Some of them have a higher octane rating than others. All the over the counter octane boosters (like 104) are simply aromatic hydrocarbons with a high octane rating. Unfortunately (unlike lead) they are not very potent in such a small quantity. One bottle of 104 might raise 93 octane fuel to 93.1 or 93.2 octane. It is NOT going to raise it a full point to 94 octane. If you want to go this route then you need a bigger quantity. Toluene (sold at paint stores and some hardware stores) is the cheapest way to go. A gallon is about $8-10. Add one gallon to 15 gallons of 93 octane and it will increase the octane rating about 1 point (to 94).
I used to use 104 with 91 premium in my 86 turbo Toyota truck. My Toyota factory trained mechanic mentioned something to the effect that it "dried out" the upper cylinder walls and cautioned me about using it. I do not know if this is true or not. I did quit using it though. Has anyone else heard of this. Mike
I have been happy with Octane Supreme 130 - it contains 60 grams of Tetraethyl lead per quart. Of course I have *NO* emmisions controls on the 66 - and I can dose it by the tank. It was easier adding the additive than trying to jockey (and store) barrels of fuel or plead for mercy at the airport. I believe that vehicles like Mike's Toyota would need to stay away from it. Most of the newer technology is adversly affected by it. I have an Innovate LM-1 to help set up my Webers and the Bosch O2 sensor for it fouls out more quickly with the additive so I don't run the additive when tuning.
A word of caution here. Mixing chemicals without adequate protection could prove dangerous since these many of these agents are poisonous or carcinogenic and can be absorbed through the skin. Organ failure or cancer can follow after prolonged exposure. Enough said.
I agree that the vast majority of octane improvers are at best useless and raise the octane a negligible amount. But, tetraethyl lead is a different animal entirely, and I also have had good luck with Octane Supreme 130 mixed according to the manufacturer's directions to obtain about 98 octane (I've used it exclusively over the course of a couple years now). The cautions given about mixing it are well taken. If it were easy to obtain I'd still opt for buying leaded race gas and mixing it with 91 unleaded, but it can be a pain to come by depending on where you live. You might want to try local motorcycle shops...they often sell race gas by the 5 gallon can.
Have a 68- 500, I use 130 for about 3-4 years now, When I gas up put one bottle per tank,& that's it. It works for me.---S.
