Gokai134 said:
And what octane do you run? Here we can only get 91 from the pump anymore, and of course it's no lead.
Hi DalEO,
from the mid to late 1980`ies catalytic converters (cars)became mandatory in Europe -> unleaded fuel was the result
From year 2000 onwards there is no leaded fuel in the EU available (except Avgas, but that is an other story)
So it´s pretty much the same as in the US.
BUT,there´s still some difference: the octan-numbers are measured in different way
Europe has ROZ-numbers the US has (ROZ+MOZ):2 -> results are not the same (please google for detailed informations)->
Our gasoline/petrol/benzin has usually 91/95/98 Octane and in most countries the 98 is already replaced with 100 octane.
MTBE is the most common additiv,
and one more BUT:every Country is making their own (specific)fuels, the fuel in finland (i.e.very cold, they add some alcohol)differs a lot from
the fuel in greece...
this doesn´t make life easier Factories to supply the "correct"(?) jetting ( Yamaha for example has (beside the jetting) totally different CDI`s
on their Offroad-bikes)
And last, but not least: Usage between US/Australia and Europe is different:
We run our bikes mostly on single-trails and you have lots of space with WOT...
Hope I could help a bit
Thanks Gokail134,
Yes that does clear some things up. I will followed your advice and googled it and here is what the first page I came upon. It's a great explanation.
Have a look:
http://en.wikipedia.org/wiki/Octane_rating
After reading this description the difference can be quite great between european and us fuels. Throughout 90% of all the discussions on jetting on this site, the assumption was that everyone was running "premium" unleaded pump gas . And, as you can see from the article over in europe, 100 octane "premium" pump gas would be about equivalent to 94 or 95 octane fuel here in the states. And as the octane rating goes up, most of the time the mixture get's richer if the jetting is left unchanged.
So, with that in mind. I woulld like Taffy to chime in here and let us know what fuel he has been running during his jetting tests. As Taffy likes to state that he can't get any of us Yanks to run a 150 range mj, perhaps that is the reason why. As stated in the article, the higher octane fuels have a much greater resistance to auto ignition, AND, and this is a big and, they have more energy for a given volume based on the fact that they have more carbon-carbon bonds. As opposed to carbon-hydrogen bonds.
Further, here in the states MTBE has been found to be BAD. It gets into the water table due to leaky tanks, and is carcinogen. So, this oxygenator has been replaced with up to 10% methanol mix to help the fuel burn more cleanly. However, according to this article, while methanol, ethanol, mixes might have a higher octane rating, they contain LESS energiy for a given volume.
THE POINT here is that if you have less energy for a given volume of fuel you will need MORE of the same fuel to deliver the same amount of energy as one that has more energy in a given volume. This is also explained by the drop off in mpg here in the states with the reformualted fuels.
Here is the article in it's entirety:
Octane rating
From Wikipedia, the free encyclopedia
The octane rating is a measure of the autoignition resistance of gasoline (petrol) and other fuels used in spark-ignition internal combustion engines. It is a measure of anti-detonation of a gasoline or fuel.
Octane number is the number which gives the percentage, by volume, of iso-octane in a mixture of iso-octane and normal heptane, that would have the same anti-knocking capacity as the fuel which is under consideration. For example, gasoline with the same knocking characteristics as a mixture of 90% iso-octane and 10% heptane would have an octane rating of 90. [1]
Contents
[hide]
* 1 Definition of octane rating
o 1.1 Measurement methods
* 2 Examples of octane ratings
* 3 Effects of octane rating
* 4 Regional variations
* 5 References
* 6 External links
[edit] Definition of octane rating
Octane is measured relative to a mixture of iso-octane (2,2,4-trimethylpentane, an isomer of octane) and n-heptane. An 87-octane gasoline, for example, has the same octane rating as a mixture of 87% (by volume) iso-octane and 13% (by volume) n-heptane. This does not mean, however, that the gasoline actually should contain these chemicals in these proportions. It simply means that it has the same autoignition resistance as the described mixture.
A high tendency to autoignite, or low octane rating, 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.
[edit] 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.
There is another type of octane rating, called Motor Octane Number (MON) or the aviation lean octane rating, which is a better measure of how the fuel behaves when under load. MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, a higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern gasoline will be about 8 to 10 points lower than the RON. Normally fuel specifications require both a minimum RON and a minimum MON.
In most countries (including all of Europe and Australia) the "headline" octane that would be shown on the pump is the RON, but in the United States, Canada and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 8 to 10 point difference noted above, this means that the octane in the United States will be about 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, would be 91-92 in Europe. However most European pumps deliver 95 (RON) as "regular", equivalent to 90-91 US (R+M)/2, and even deliver 98 (RON) or 100 (RON).
The octane rating may also be a "trade name", with the actual figure being higher than the nominal rating.[citation needed]
It is possible for a fuel to have a RON greater than 100, because isooctane is not the most knock-resistant substance available. Racing fuels, straight ethanol, AvGas and liquified petroleum gas (LPG) typically have octane ratings of 110 or significantly higher - ethanol's RON is 129 (MON 102, AKI 116). Typical "octane booster" additives include tetra-ethyl lead and toluene. Tetra-ethyl lead is easily decomposed to its component radicals, which react with the radicals from the fuel and oxygen that would start the combustion, thereby delaying ignition. This is why leaded gasoline has a higher octane rating than unleaded.
[edit] Examples of octane ratings
The octane ratings of n-heptane and iso-octane are respectively exactly 0 and 100, by definition. For some other hydrocarbons, the following table[2][3] gives the road octane numbers.
n-octane -10
n-heptane 0
2-methylheptane 23
n-hexane 25
2-methylhexane 44
1-heptene 60
n-pentane 62
1-pentene 84
n-butane 91
cyclohexane 97
iso-octane 100
benzene 101
E85 Ethanol 105
Methane 107
Ethane 108
Toluene 114
Xylene 117
[edit] Effects of octane rating
Higher octane ratings correlate to higher activation energies. Activation energy is the amount of energy necessary to start a chemical reaction. Since higher octane fuels have higher activation energies, it is less likely that a given compression will cause knocking. (Note that it is the absolute pressure (compression) in the combustion chamber which is important - not the compression ratio. The compression ratio only governs the maximum compression that can be achieved).
Octane rating has no direct impact on the deflagration (burn) of the air/fuel mixture in the combustion chamber. Other properties of gasoline and engine design account for the manner at which deflagration takes place. In other words, the flame speed of a normally ignited mixture is not directly connected to octane rating. Deflagration is the type of combustion that constitues the normal burn. Detonation is a different type of combustion and this is to be avoided in spark ignited gasoline engines. Octane rating is a measure of detonation resistance, not deflagration characteristics.
It might seem odd that fuels with higher octane ratings explode less easily, yet are popularly thought of as more powerful. The misunderstanding is caused by confusing the ability of the fuel to resist compression detonation as opposed to the ability of the fuel to burn (combustion). However, premium grades of petrol often contain more energy per litre[citation needed] due to the composition of the fuel as well as increased octane.
A simple explanation is that carbon-carbon bonds contain more energy than carbon-hydrogen bonds. Hence a fuel with a greater number of carbon bonds will carry more energy regardless of the octane rating. A premium motor fuel will often be formulated to have both higher octane as well as more energy. A counter example to this rule is that ethanol blend fuels have a higher octane rating, but carry a lower energy content on a volume basis (per litre or per gallon). The reason for this is that ethanol is a partially oxidized hydrocarbon which can be seen by noting the presence of oxygen in the chemical formula: C2H5OH. Note the substitution of the OH hydroxyl radical for a H hydrogen which transforms the gas ethane (C2H6) into ethanol. Note that to a certain extent a fuel with a higher carbon ratio will be more dense than a fuel with a lower carbon ratio. Thus it is possible to formulate high octane fuels that carry less energy per liter than lower octane fuels. This is certainly true of ethanol blend fuels (gasohol), however fuels with no ethanol and indeed no oxygen are also possible.
In the case of alcohol fuels, like Methanol and Ethanol, since they are partially oxidized fuels they need to be run at much richer mixtures than gasoline. As a consequence the total volume of fuel burned per cycle counter balances the lower energy per unit volume, and the net energy released per cycle is higher. If gasoline is run at its preferred max power air fuel mixture of 12.5:1, it will release approximately 19,000 BTU (about 20 MJ) of energy, where ethanol run at its preferred max power mixture of 6.5:1 will liberate approximately 24,400 BTU (25.7 MJ), and Methanol at a 4.5:1 AFR liberates about 27,650 BTU (29.1 MJ).
To account for these differences, a measure called the fuel's specific energy is sometimes used. It is defined as the energy released per air fuel ratio. For the case of gasoline compared to the alcohol fuels the specific energies are as follows:
Fuel Net energy Units
Gasoline 2.92 MJ/kg
Ethanol 3.00 MJ/kg
Methanol 3.08 MJ/kg
Using a fuel with a higher octane lets an engine run at a higher compression without having problems with knock. Actual compression in the combustion chamber is determined by the compression ratio as well as the amount of air restriction in the intake manifold (manifold vacuum) as well as the barometric pressure, which is a function of elevation and weather conditions.
Compression is directly related to power (see engine tuning), so engines that require higher octane usually deliver more power. Engine power is a function of the fuel as well as the engine design and is related to octane ratings of the fuel... power is limited by the maximum amount of fuel-air mixture that can be forced into the combustion chamber. At partial load, only a small fraction of the total available power is produced because the manifold is operating at pressures far below atmospheric. In this case, the octane requirement is far lower than what is available. It is only when the throttle is opened fully and the manifold pressure increases to atmospheric (or higher in the case of supercharged or turbocharged engines) that the full octane requirement is achieved.
Many high-performance engines are designed to operate with a high maximum compression and thus need a high quality (high energy) fuel usually associated with high octane numbers and thus demand high-octane premium gasoline.
The power output of an engine depends on the energy content of its fuel, and this bears no simple relationship to the octane rating. A common myth amongst petrol consumers is that adding a higher octane fuel to a vehicle's engine will increase its performance and/or lessen its fuel consumption; this is falseâ€â€
regarding dynos and jetting-kit. He may have a point in what he is saying. but some off his products seams good. I think.
