Octane number, also known as octane rating, is a measure of the performance of gasoline (petrol). It is an important aspect that determines the quality of gasoline and is widely used to compare gasoline products. In this article, we will explore what octane number is, how it is determined, and its significance in the performance of gasoline.
Octane number is a numerical value that is assigned to gasoline based on its ability to withstand compression before detonation. The higher the octane number, the more compression the gasoline can withstand without exploding.
In simple terms, gasoline is made up of a mixture of hydrocarbon compounds that ignite and burn when exposed to heat and pressure. The rate of ignition and combustion is determined by the composition of the gasoline, and this is where octane number comes in.
The octane number is determined through a test procedure called the Research Octane Number (RON) test. This test measures the ignition quality of gasoline by comparing it to a reference gasoline with an octane rating of 100. The gasoline being tested is subjected to increasing levels of compression and pressure until it detonates. The higher the compression that can be achieved without detonation, the higher the octane rating.
The other test procedure is the Motor Octane Number (MON) test, which measures the performance of gasoline in an actual engine. This test is more representative of real-world driving conditions and is considered a better indicator of gasoline performance.
The significance of octane number lies in its impact on the performance of an internal combustion engine. The octane rating determines the gasoline’s ability to resist “knocking” or “pinging”, which is the uncontrolled combustion of fuel that results from the gasoline detonating prematurely.
If the gasoline has a low octane rating, it will ignite too quickly in the engine, causing knocking and pinging, which can result in engine damage. On the other hand, if the gasoline has a high octane rating, it will resist knocking and pinging, providing better performance and engine protection.
The right octane rating for a vehicle will depend on the manufacturer’s specifications. Most vehicles run well on regular unleaded gasoline with an octane rating of 87, but some higher-performance engines may require a higher octane rating to run properly.
It’s important to note that using a higher octane rating than what is recommended by the manufacturer will not necessarily improve engine performance. In fact, it can be a waste of money, as the engine will not be able to take advantage of the additional octane.
In petrol engines, the air-fuel mixture is compressed to high pressure and is ignited in the cylinders. Hence, the compressibility of petrol is vital for the performance of the engine. Petrol with higher octane numbers is more compressible than that of lower octane numbers. The use of low octane petrol leads to the problem of engine knocking and is harmful to the engine. However, a low octane number is suitable for Diesel engines. But, the fuel should have a high cetane number. Cetane number indicates the combustion speed of diesel fuel.
Hindustan Petroleum Corporation Ltd (HPCL) had also launched Octane 99 petrol name as ‘poWer 99’ recently in Tamil Nadu. Indian Oil Corporation (IOC) has recently launched India’s 1st 100 Octane petrol. It is a superior quality of fuel that is available only in a few countries.