In the United States at least there are 3 grades of unleaded gasoline at most pumps. Does it really matter what grade of gas you use? Can I use the lowest grade one week and the next week get premium if I can afford it? Does it help with milage or does it keep your engine clean? What is the difference?
In: Engineering
Premium gas denotes higher octane rating. The higher the octane – the higher compression (how much pressure it can take) it can handle.
Engines work by mixing gas and air, and igniting the mixture. The resulting explosion (fire) pushes a piston which then turns a crank… let’s just say moves the car.
**Allegory** – Imagine two springs: one is soft and one is stiff. The softer spring you can push down and release and it might jump off the ground a few inches. The stiffer spring will be harder to push down but once you release, would probably jump off the ground quite a bit higher.
The principle is the same for engines: lower octane gas can’t be compressed as hard and thus don’t create as much power. Higher octane gas can be compressed harder and the resultant explosion (release) is more powerful.
Higher octane gas can be compressed more and the resulting explosion produces more power (aka horsepower).
**Advanced explainer:** to take advantage of higher octane gas you generally need to do something called “Forced induction”. Forced induction is a fancy way of saying “force more air” into the cylinder (where gas and air mixes). Because the higher octane gas can be compressed more, it also needs more air in order to fuel the bigger explosion. The only way to get that much air and quickly enough into the cylinder is through forced induction (turbo/supercharger).
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