Octane is a chemical that once upon a time was used to decrease knock in engines. In the 70's the government mandated that "octane ratings" advertised by the oil companies to be the average of "motor" and "research" (r+m)/2=octane rating. Higher octane has a higher threshold of energy level required to start combustion, therefore there is less chance of detonation. If a engine is not detonating, higher octane WILL MAKE LESS POWER. Use the lowest octane without detonation. Remember that the knock sensor on our cars are pretty sensitive and the EEC will RETARD the timing when knock is detected.
There are two types of detonation, part throttle and full throttle. For part throttle detonation, a higher research octane is needed. For full throttle detonation, higher motor octane is needed. These numbers are not published on the fuel pump, and each oil company has slightly different numbers. These mixes also change during the season, different temperature weather requires different mix fuel. Changing brands of petrol during the year can minimize detonation in engines that operate "near the edge".
Higher octane fuel does NOT mean higher power (essentially the same amount of energy in all petrol). However, higher percentage of octane molecules does. However octane rating is obtained by various means, and seldom by the more expensive method of increasing the percentage of actual octane molecules. Octane rating is simply a measure of detonation resistance, which can be achieved by adding chemicals (like lead) that inhibit combustion. Actual high levels of octane molecules raised the threshold energy by raising the top of the energy release curve, making the drop, and hence the energy release, greater.
Higher REAL octane would increase power, but it's doubtful you could get it, and if you did find a source,you'd be hard pressed to verify it was the real thing. If someone offered me gasoline with a higher percentage of octane, I'd want to talk to a chemist at the refinery it came from, and then MAYBE I'd think about using it.
Rate of reaction(along with initialization energy) is a function of the type of molecules that are being combusted and it will vary dependent on the type of hydrocarbon used. The reduction in detonation does indeed result from an increased initiation energy, but the fact remains that you need to increase spark advance when using higher octane fuel to compensate for a slower rate of reaction. I somewhat mistated in my previous post that higher octaneallows larger advance, whereas you rather than allowing, you actually needto increase advance to compensate for a slower rate of reaction. The real advantage of higher octane fuel is that you can cram more oxygen into the cylinders without detrimental preigntion effects (oxygen is the limiting reagent, so this is what we want more of).
sorry... thatsa bit long really isn't it!?
Bottom line is that the spark plugs in the Ignis Sport are only designed for fuel of up to 97 or 98ron. If you want to use Tesco's 99ron effectivley (5hp increase I estimate) you will need to upgrade your spark plugs. You can use Swift GTI upgrade ones I think.
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