When you switch race fuels, you'll likely have to change the jets in your carb. Here Circl
Now the simple reason you should care about the octane rating is that it shows the resistance of the fuel to uncontrolled combustion; such as knocking, pre-ignition and detonation all of which, at a minimum, reduce the efficiency of your engine. The higher the octane of a fuel the greater its ability to withstand cylinder pressures before uncontrolled combustion takes place.
Meth vs. Gas; Which is better?
Another fuel debate often heard in the pits around country is, should I run methanol or gasoline? To delve deeper into this subject let's first go back to school and look at the differences between the two.
Gasoline is one of the resulting products from the Fractional Distillation of crude oil. Various components of crude oil have different molecular sizes, weights, and boiling temperatures. Simply stated the refining process separates those components by heating the crude oil to the boiling point. As the oil boils the resulting vapor enters the bottom of a long column called the fractional distillation column which is filled with trays or plates. These trays have many holes or bubble caps (like a loosened cap on a soda bottle) in them to allow the vapor to pass through. As the vapor rises through the trays in the column, it cools. When a component in the vapor reaches a height where the temperature of the column is equal to that substance's boiling point, it will condense to form a liquid. That liquid is in turn collected. As you can see from Chart A, gasoline is collected at the top of the fractional distillation column.
With the bowl detached, he can remove the metering body. -Rob Fisher
On the flip side, Methanol (also known as methyl alcohol) is an alternative fuel made from woody plant fiber, coal or natural gas; it is used primarily as a supplement to gasoline. It can also be harvested from the methane gas in landfills in addition to fermented waste products such as sewage and manure. To digress into the environmental world for a minute methanol is one of those fuels that can be sustainably produced depending on its origins. Converted from methane gas captured from landfills it can be a source of constantly renewable energy. Taken as the by-product of natural gas production (a fossil fuel) it's no more green than standard gasoline.
Environmental lessons aside, pure methanol is primarily used as racing fuel. One of the major pros of methanol versus gasoline is that it has the ability to run at higher compression ratios than gasoline, translating into more power. As any Dirt Late Model racer who favors a methanol-fired engine will tell you, the primary reason they run it is more power. It also tends to run cooler than gasoline.
On the downside, while it's not as volatile as gasoline, it does burn with an invisible flame, making it hard to tell when you're on fire. It's also highly corrosive meaning that your post race maintenance schedule is going to take longer than with a gasoline engine. Your biggest trade off is that it has a 50 percent energy ratio-that means it produces half of the power content of gasoline. In other words, you need to consume more methanol to generate the same power as gasoline. Still, the additional power produced by a methanol engine is enough to make many racers run the colorless fuel.
The old jets require a flat screwdriver to remove, which could cause damage. -Rob Fisher
Burns boils it down to this, "Racing fuels in the past weren't all that good and many people felt methanol made more power. But today's good race gasolines can make as much if not more power than methanol."