Regular VS Premium

[Mr. Jollypants]

The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Lower-octane gas can handle the least amount of compression before igniting. The compression ratio of your engine determines the octane rating of the gas you must use in the car, which is why we should really follow the advice of the engineers who designed our engines. (Don't put 92 in your regular car thinking you are doing "good.")

The name octane comes from the following fact: When you take crude oil and "crack" it in a refinery (technical term is fractional distillation), you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, you have heard of methane, propane and butane. All three of them are hydrocarbons. Methane has just a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has eight carbons chained together.

It turns out that heptane (7) handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Isooctane is assigned an octane number of 100. It is a highly branched compound that burns smoothly, with little knock. On the other hand, heptane is given an octane rating of zero. It is an unbranched compound and knocks badly.

So, as you may have already guessed, 87-octane gasoline is gasoline that contains 87% octane and 13% heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.

And have you ever gone up to a pump and seen that mathematical formula [(R+M)/2] on one of those inspection stickers? One value is the research octane number (RON), which is determined with a test engine running at a low speed of 600 rpm. The other value is the motor octane number (MON), which is determined with a test engine running at a higher speed of 900 rpm. If a gasoline has an RON of 94 and a MON of 84, then the posted octane number would be the average of the two values: 89.

 

[98ej8]

good info
i guess im switching down haha

 

[EG6 LIFE]

^^^listen to this guy knos his stuff thanks man i always thought higher octane produces beter combustion but u do gotta be careful what reg gas ur getin i have s**t from some gas stations that dont even smell like gas