We are familiar with the terms octane rating and engine knock and we know they are an important part of running our vehicles properly, but do we know exactly what they are?
To prevent engine knock we know that we need a certain gas and we do buy it. We know we which gas to choose because our car's owner manual tells us which grade we should use.
Did you know that engine knock can actually cause damage to your vehicles by cracking the cylinder heads or the pistons and could destroy your engine?
Here is what causes engine knock. Very simply, it is the un- even or un-smooth combustion of your car's gasoline. The knock is caused when high pressure rises after ignition. The air and fuel mix in your engine need to burn evenly in your vehicle's combustion chamber. If the mix is burned too early (pre-ignition) or too late, it will cause extra molecules or pressure waves to be produced and they will cause engine knock.
In very simple words, your gas and air mix are not burning perfectly at the correct time, and this is causing parts of your engine to knock.
To alleviate this problem iso-octanes (more products of crude oil) were introduced to gasoline to help the air/gas mix burn more consistently, at the correct time, not before. When the iso-octanes were added, at different ratios we needed something to differentiate them, and that is where octane rating number comes in. It is the different mixes of gasoline and the iso-octanes added to it that determine the octane rating of the gasoline.
Iso-octane is also known as 2,2,4 trimethyl pentane. It is added together with n-heptane and depending on the mix it determines the octane rating number. Usually the rating numbers range from 87 to 94. These are the numbers we are all familiar with because we see them on the gas pumps.
Just because one gas has a higher octane rating than another, it does not mean this is the best one for your car. Each auto manufacturer has tested their cars and has found which octane will run your car at peak performance.
Make sure you check your owners manual for the proper octane rating for your vehicle. You may be hurting your vehicle more than your helping it by using a higher, but incorrect, octane amount.