Octane is a measure of a fuel’s ability to resist “knocking” or “pinging” during combustion, which is caused by the air-fuel mixture detonating prematurely in the engine. Generally, higher octane fuels are used in high-performance engines that operate at higher temperatures and pressures, and require fuels with greater resistance to knocking.
There are several different octane rating scales used around the world, but the two most commonly used are the Research Octane Number (RON) and the Motor Octane Number (MON). The RON measures a fuel’s knock resistance under mild operating conditions, while the MON measures its knock resistance under more severe conditions. The octane rating of a fuel is usually expressed as the average of the RON and MON values, and is known as the Anti-Knock Index (AKI), which is used in North America.
In the United States, the highest octane gas available at most gas stations is typically premium fuel, which has an AKI of 91-93. Some gas stations may offer “ultra-premium” fuel with an AKI of 94 or higher, but these fuels are relatively rare and are typically only found at specialty gas stations or performance shops.
However, there are some specialty fuels available that have even higher octane ratings. For example, racing fuels used in high-performance race cars can have octane ratings as high as 120 or more. These fuels are typically not available to the general public and are only sold to race teams and other high-performance enthusiasts.
One reason why these fuels are not widely available is that they are often very expensive, with prices that can be several times higher than regular pump gasoline. In addition, they may not be suitable for use in normal passenger cars, as they may not meet emissions or other regulatory requirements.
It’s worth noting that simply using a high-octane fuel does not necessarily improve a car’s performance, unless the car is specifically designed to take advantage of the higher octane rating. In fact, using a higher octane fuel than is recommended for a particular vehicle may actually reduce performance and fuel economy, as the engine may not be able to fully burn the fuel.
In summary, the highest octane gas available to the general public in the United States is typically premium fuel with an AKI of 91-93. Specialty fuels used in high-performance race cars can have even higher octane ratings, but are generally not available to the general public and may not be suitable for use in normal passenger cars. Using a high-octane fuel does not necessarily improve a car’s performance unless the engine is specifically designed to take advantage of it.
