In this note, we will learn a topic called “About Octane Number and Cetane Number” and Its Importance and Ratings. Welcome to Poly Notes Hub, a leading destination for Engineering Notes for Diploma and Degree Engineering Students.
Author Name: Arun Paul.
Octane Number and Cetane Number
1. Petrol (Gasoline) – Octane Number
- Definition: The octane number measures a fuel’s capacity to resist knocking during combustion in engines with spark ignition.
- Importance: A higher octane rating indicates more resistance to early ignition, which is essential for powerful engines.
- Typical Octane Ratings:
- Regular Petrol: 87 octane (common in countries like the US).
- Premium Petrol: 91–98 octane (recommended for high-compression engines, sports cars, or luxury vehicles).
- Racing Fuel: 100+ octane (used in specialized engines).
2. Diesel – Cetane Number
- Definition: The cetane number determines how easily diesel fuel ignites in compression-ignition engines.
- Importance: A greater cetane number leads to smoother combustion, improved cold start performance, and lower emissions.
- Typical Cetane Ratings:
- Standard Diesel: 40–55 cetane (varies by region and grade).
- Premium Diesel: 55+ cetane (offers enhanced performance and reduced engine noise).