What Octane Gasoline Should a Land Rover Range Rover Use?

[Larry]

Land Rover Range Rover uses 95 octane gasoline. Currently, gasoline is available in four grades: 89 (formerly 90), 92 (formerly 93), 95 (formerly 97), and 98 (a newly introduced grade). These numbers represent the octane rating of the gasoline, indicating its anti-knock properties, and are unrelated to the cleanliness of the fuel. Filling up according to the engine's compression ratio or the requirements specified in the user manual is more scientific, economical, and allows the engine to perform at its best. During the design phase of the car engine, the fuel grade is determined based on the compression ratio. Engine Compression Ratio: The compression ratio is a crucial structural parameter of the engine, representing the ratio of the gas volume when the piston is at the bottom dead center (start of compression) to the gas volume when the piston is at the top dead center (end of compression). From the perspectives of power and efficiency, a higher compression ratio is generally better. A high compression ratio improves power output, thermal efficiency, and enhances vehicle acceleration and top speed. However, due to limitations in cylinder material performance and gasoline combustion knock, the compression ratio of gasoline engines cannot be too high. High-compression-ratio vehicles require high-octane fuel. The higher the octane rating, the slower the fuel burns, reducing combustion knock, which is suitable for engines with higher compression ratios. Conversely, lower-octane fuel burns faster, causing more combustion knock, and is suitable for engines with lower compression ratios. The octane rating also affects the engine's ignition timing. Lower-octane gasoline burns faster, requiring a retarded ignition angle, while higher-octane fuel burns slower, necessitating an advanced ignition angle.