DON'T GET CONNED!

RON - RESEARCH OCTANE NUMBER DOES NOT EQUAL MORE OCTANE OR MORE POWER!

The number is related to how liable the fuel is to auto-ignite under compression. Shell RON100 has achieved this reduced autoignitability by adding ethanol - a less energy dense fuel than octane.

It's a big con job.

It's true that if you tune an engine to a fuel which has a low auto-ignition property then you might tweak the engine's full potential power; but Shell - 100 adds nothing in and of itself and by diluting/blending with ethanol actually gives you an inferior product to pure petroleum distillates.


From Wikipedia...



Octane is measured relative to a mixture of isooctane (2,2,4-trimethylpentane, an isomer of octane) and n-heptane. An 87-octane gasoline has the same knock resistance as a mixture of 87% isooctane and 13% n-heptane, which does not mean that the gasoline actually contains 87% isooctane. It simply means that it has the same autoignition resistance as a mixture of 87% isooctane and 13% n-heptane. A low octane rating means that the fuel has a high tendency to autoignite, which is undesirable.

A high tendency to autoignite is undesirable in a gasoline engine but desirable in a diesel engine. The standard for the combustion quality of diesel fuel is the cetane number. A diesel fuel with a high cetane number has a high tendency to autoignite, as is preferred.
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Measurement methods

The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel through a specific test engine with a variable compression ratio under controlled conditions, and comparing these results with those for mixtures of isooctane and n-heptane.