Um, to the squabble over what octane means:
Octane rating - Wikipedia, the free encyclopedia
Translation from a person with a Physics Degree (me): The point of an internal combustion engine is to combust fuel to release energy, doing work over a certain time (aka power = work/time). Thus more power with more energy or less time.
If the fuel has a higher resistance to combustion, than you will take more time to combust. Thus the power out put is lower assuming that you have released the same amount of energy from the fuel (assuming basically that a higher octane fuel is simply a lower octane fuel with octane raising additives, which is generally the case).
Damage: probably not, but the comments about deposits remaining I can get on board with as the likelihood of complete combustion within the same amount of time as lower octane fuel is pretty slim.
However, octane is a rating of resistance to detonation not combustion, although the two are related. Detonation, in car terms, means that the fuel has combusted due to heat and pressure premature to the desired instant of ignition. In general terms, detonation is uncontrolled combustion that occurs supersonically (the flame front travels faster than sound)
Combustion, in automotive terms, refers to the planned burning of fuel ignited, in a gasoline engine, by a spark plug. This usage of combustion refers to the deflagration form of combustion, basically a sub-sonic flame front
What all this means scientifically to the layman (most of us): Although octane measures resistance to "detonation", the same proporties that cause resistance to this inhibit "combustion." Thus, a flame front will travel slower in a higher octane fuel than a lower octane one. Thus, one has to time their engine to ignite fuel earlier for a higher octane fuel to achieve complete combustion at the same point in time as a lower octane fuel.
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BOTTOM LINE: I do encourage you to read through all the above, quite educational and good for all car enthusiats and I enjoyed writing it. However this basically means that in an unmodified engine, use the lowest octane fuel that the engine was designed for (for my s14, there is a little sticker on the filler door that says use
92 octane aka Premium) for best performance and engine health. Lower octane risks detonation, higher octane lowers power output and risks deposits in the cyclnders, although this is prolonged use, in the short term you would be fine as the deposits would be washed by the detergents in all modern gas.
Bottom Bottom Line: if you want the smell, try to find an additive that simulates it or mix 87 octane and race gas (find out the octane) to achieve the ideal 92 octane your engine craves (anyone seen Idiocracy? 92 Octane, it's what kas crave!!! :-P)
Konrad
Edit: I forgot to insult people :-P (seriously, though, dont take this that way, I mean it to help others not insult you def)
Quote:
Originally Posted by Def
This thread is full of fail.
Combustion rate is NOT directly related to octane rating of a fuel. There is some race gas that has a faster combustion rate than normal pump gas, and some that has a slower combustion rate of the gas. VP Import stuff in particular touts its higher combustion rate to enable a small increase in power at very high RPM(<8000 RPM).
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"Combustion" rate is indeed indirectly related to octane rating (combustion in automotive terms, in scientific terms detonation is a type of combustion and therefore octane is directly related). My thoughts on the fuel that burns faster is that there must be some sort of catelyst that causes the heat to spike when ignited that is inert during the compression stage of the Otto cycle. Cool shit there, if I am correct, but this is an exception not the rule.
Quote:
Originally Posted by Def
Absolutely 100% incorrect on all counts. Burn kinetics at the same octane rating, but with a fuel made of up different compounds(more aromatics, more TEL, etc.), will be vastly different.
Tuning cars on different fuels, and learning a few things about combustion engineering makes this readily apparent.
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Not entirely true, octane rating is not separate of composition, it simply compares detonation point versus a standard. That being said, different additives may catalyze the reaction creating these differences. I am not an expert in different gas types, this is simply an analysis based on physics/chem/thermo