What does the RON in the Fuel gotta do with the Performance

Shell V-Power Racing, Caltex 100RON, are these just Gimmicks?
Not so I think as the RON is a factor, but also the additive in the fuel does it’s job better.

I remember using those ‘racing rocket fuel’ claims to have 100% octane levels….. and well, those methanol does it’s job better.

I REFER to the letter, ‘Rein in pump prices and polluting fuels’ by Mr Hwang Liang Keng (ST, Dec 19). Mr Hwang mentioned that California laws prohibit the sale of petrol with an octane level higher than 91.

The octane number is actually an imprecise measure of the maximum compression ratio at which a particular fuel can be burned in an engine without pre-detonation. There are actually two numbers - RON (research octane number) and MON (motor octane number). The RON simulates fuel performance under low severity engine operation. The MON simulates more severe operation that may be incurred at high speed or high load and can be as much as 10 points lower than the RON.

In Singapore, the number at petrol pumps is the RON. However, in the United States, it usually indicates ‘mean’ octane number, that is, (RON + MON)/2, or the average of both the RON and the MON. This is why there is an apparent discrepancy between octane values of petrol in the US and the rest of the world. For example, RON95 unleaded in Singapore is 95 octane but equivalent to American (RON+MON)/2 89 octane.

In the US, low-altitude petrol stations typically sell three grades of petrol with octane ratings of 87, 89 and 91. High-altitude stations typically also sell three grades, but with lower values - 85, 87 and 89. This is because, for every 300m increase in altitude, the RON value goes down by 0.5.

It is also a common misconception among car enthusiasts that higher octane means more power. This is simply not true. The myth arose because high-performance vehicles require higher-octane fuels. Without understanding why, a certain section of the car subculture decided this was because higher-octane petrol means higher power.

The reality is a little different. Power is limited by the maximum amount of fuel-air mixture that can be jammed into the combustion chamber. Because high-performance engines operate with high compression ratios, they are more likely to suffer from detonation. And so to compensate, they need a higher-octane fuel to control the burn.

So yes, sports cars do need high-octane fuel, but it is not because the octane rating somehow gives more power. High-octane fuel is required because the engine develops more power because of its design.

Huang Yu-kang