[Tomkreiner]

In reply to the thread about Octane "boosters."

So that everyone on the forum is on the same page, octane wise - at least, there is no basis for numerical determination of octane numbers, or octane ratings. The octane meter was developed by Shell Oil during the early 1940's, and is known as a contrivance. It registers a noise based upon a sound pickup placed in the cylinder head of a Cooperative Fuels Research Engine (CFR). By definition, pure IsoOctane (or 2,2,4-trimethylpentane as it's known by Chemists) has an octane rating of 100. It tends to be quite a bit more expensive than the other principal component of pump gas, which is called Normal Heptane, or n-heptane in the industry. N-Heptane by definition, has an octane rating of 0. There is an ASTM Test Method that spells out how to run both the Motor and the Research methods of octane determination, and they use several other items, such as Toluene to calibrate the octane meter. This test is run hourly at every refinery in the world, to provide continuous certification of the fuels being blended and sold.

When the two HC's are blended in the correct proportions, the fuel achieved will have two different octane ratings, one of which is determined by the Motor Method, and the other by the Research Method. Pump gas has its own rating, which is a combination of the two, and is expressed as: (R+M)/2.

Now, when additives are blended into a fuel, like tetraethyl lead (TEL), the octane rating of the fuel is raised considerably. Pure IsoOctane can be boosted to around 108, maybe higher, I'm not sure, as its been 25 years since I ran an octane test. The use of TEL was rampant from the 1940's thru 1970's and it was used to take a fuel of 80 octane and boost it to an 87 level so it could be used in cars. (Of all of the additives, TEL was the very best, and actually made a huge fortune for Ethyl Corporation - its manufacturer, but that's for someone else to comment on.)

Today, we get a smaller boost from ethanol, or even methanol, but not nearly like we did from TEL. I know of no other HC additive that even comes close to the effect of TEL, and without testing and a CFR engine report, I would seriously question the claims of octane boost - and so should you. (As my Thesis Prof used to say: "fellas, without data, you're just another swinging dick with an opinion.")

More may be learned about octane ratings from Wikipedia if you're interested.