I understand how octane is measured and what it means. You and I have some similar automotive background, I'm currently a Senior Design Engineer at an OEM vehicle manufacturer. While I never spent time testing octane I think I'm qualified to say that engine design and chemical engineering have changed A LOT in the 40-odd years since that article was published. Bio fuels, advances in fuel metering and ignition control and refining techniques have changed the game. I don't dispute that what you're saying isn't based on fact and would probably work well on older, carbureted engines, the materials used in more modern engines and how those engines were designed may not play nicely with a home-brewed high octane fuel, so giving advice that was true 40 years ago no longer applies.
From the Sunoco link provided above:
Sunoco.com wrote:First you need to calculate the percentage of each fuel that will be in the final mixture. Then, use this equation to find your octane:
( [ % Fuel A ] x [ Octane of Fuel A ] ) + ( [ % Fuel B ] x [ Octane of Fuel B ] ) = Octane of Mixture
Here’s an example. Let’s say you mix 3 gallons of 110 with 2 gallons of 100 and you want to know the octane of the resulting 5 gallon mixture.
The percentage of 110 in the mix is 3/5 = 0.60 (60%).
The percentage of the 100 octane fuel in the mix is 2/5 = 0.40 ( 40%).
Plugging the information into the equation:
(0.60 x 110) + (0.40 x 100) = 66 + 40 = 106
So the octane of the resulting mixture is 106.
You can also determine the oxygen content of the mixture the same way – just use the oxygen content information we provide in place of the octane numbers.