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.
Regardless of what the chemistry and other things might or might not say - I am glad it has been proven that Optimax Extreme 100 is a better fuel than Optimax 98..... WHEN TUNED.
At least we got some data there
What I'm also interested in however, is whether there are gains when using this on an untuned NA car - like a Euro Accord. (Or a Turbo car.) Especially without using aftermarket computer to tune things.
Also how does other fuels like Mobil Synergy 8000 compare with Optimax 98 and Optimax Extreme 100, BP Ultimate, etc.
End of the day though, I have tried all these various fuels (except for Extreme 100) and they're all pretty much the same. Engine sounds different when running Synergy 8000 though, but unlike my previous Turbo car running this fuel - I couldn't really tell a difference between it and Optimax 98. I just use it anyway, because the engine sounds to combust a bit more better and I THINK there might be a lil bit of power in it.... but like AARONNG said it might just be my placebo effect lol.
Ethanol, as you mention does not contribute it's bonded oxygen molecules to further enhance the combustion process. However, I fail to see how you come to the conclusion that because ethanol combustion (in the presence of sufficient oxygen) is gobbling up more oxygen than the most common compound in fuel, octane (formula C8H18) that it somehow reduces the ability of the fuel to act optimally.
I'm just debunking the myth that ethanol acts like nitrous oxide where it gives extra O2 molecules for combustion. It's a very common misconception that ethanol supplies extra oxygen for combustion. I was just illustrating that instead of providing oxygen, the combustion of ethanol actually consumes oxygen.
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Originally Posted by drdrei
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