Finally, an answer to your Petrol Grade Questions.
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For all people who have been asking about Petrol grades and octane numbers. Here's the answer.
Hopefully mods make this a sticky.
http://straitstimes.asiaone.com/portal/site/STI/menuitem.c2aef3d65baca16abb31f610a06310a0/?vgnextoid=7532758920e39010VgnVCM1000000a35010aRCRD&vgnextfmt=vgnartid:7bc9364e934bf010VgnVCM100000430a0a0aRCRD
Dec 25, 2006
Higher-octane petrol does not give more power
I REFER to the letter, 'Rein in pump prices and polluting fuels' by Mr Hwang Liang Keng (ST, Dec 19). Mr Hwang mentioned that California laws prohibit the sale of petrol with an octane level higher than 91.
The octane number is actually an imprecise measure of the maximum compression ratio at which a particular fuel can be burned in an engine without pre-detonation. There are actually two numbers - RON (research octane number) and MON (motor octane number). The RON simulates fuel performance under low severity engine operation. The MON simulates more severe operation that may be incurred at high speed or high load and can be as much as 10 points lower than the RON.
In Singapore, the number at petrol pumps is the RON. However, in the United States, it usually indicates 'mean' octane number, that is, (RON + MON)/2, or the average of both the RON and the MON. This is why there is an apparent discrepancy between octane values of petrol in the US and the rest of the world. For example, RON95 unleaded in Singapore is 95 octane but equivalent to American (RON+MON)/2 89 octane.
In the US, low-altitude petrol stations typically sell three grades of petrol with octane ratings of 87, 89 and 91. High-altitude stations typically also sell three grades, but with lower values - 85, 87 and 89. This is because, for every 300m increase in altitude, the RON value goes down by 0.5.
It is also a common misconception among car enthusiasts that higher octane means more power. This is simply not true. The myth arose because high-performance vehicles require higher-octane fuels. Without understanding why, a certain section of the car subculture decided this was because
higher-octane petrol means higher power.
The reality is a little different. Power is limited by the maximum amount of fuel-air mixture that can be jammed into the combustion chamber. Because high-performance engines operate with high compression ratios, they are more likely to suffer from detonation. And so to compensate, they need a higher-octane fuel to control the burn.
So yes, sports cars do need high-octane fuel, but it is not because the octane rating somehow gives more power. High-octane fuel is required because the engine develops more power because of its design.
Huang Yu-kang -
in short, higher octane prevents pinging or engine knocking. so if you're using lower octane without experiencing engine knocking, there's no point in getting higher octane.
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not only pinging, but also gives u better performance cos higher octane is more pure,resulting in better and complete combustion. also emits less CO2 also. might be wrong hereOriginally posted by madcampus:in short, higher octane prevents pinging or engine knocking. so if you're using lower octane without experiencing engine knocking, there's no point in getting higher octane. -
They prevent engine knocking
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It really depends on what you mean by "pure"Originally posted by casshern:not only pinging, but also gives u better performance cos higher octane is more pure,resulting in better and complete combustion. also emits less CO2 also. might be wrong here
but as for CO2 wise, i think it should be the same.
California has one of the strictest emission standards, for them to disallow anything more that RON 92 must have a reason behind. -
oic, read it up somewhere tat higher octane emits less CO2, or rather more environmental friendly.Originally posted by Ponders:It really depends on what you mean by "pure"
but as for CO2 wise, i think it should be the same.
California has one of the strictest emission standards, for them to disallow anything more that RON 92 must have a reason behind. -
They did a fuel test here on the different fuel grades in Australia
Ron 92, Ron95 and Ron98...
The test showed that using Ron95 fuel, the car was able to achieve a 10-15% increase in mileage over the Ron92. Not much difference in using Ron98 and Ron95. -
The one i read was that higher octane fuel contains more aromatics and thus more pollutantsOriginally posted by casshern:oic, read it up somewhere tat higher octane emits less CO2, or rather more environmental friendly. -
lower ron petrol is usually higher in sulphur which is a poison to the catalysts in the catalytic converters, hence emissions tends to be higher ie NOx SOx...but higher ron petrol is high in aromatics and benzene which again are carcinogenic compounds...but we are moving towards clean fuels which calls for euro4 standards (which are currently being implemented for diesel)...so in the future, sulphur content of gasoline will be only 50ppm and benzene level no more than 1vol%...
but as for performance wise...a high ron will not increase performance, but you can tune you engine more agressively if you pump a higher ron petrol...and hence better performance...
and there is no such thing as a pure petrol!! gasoline is basically a blend of many refinery products... -
hmmmm ... interesting .... in Canada I used to pump 91 mean for my wreck, until higher prices forced me down to 87, I don't see any noticeable difference actually ....
then I realised one day as I was reading the fine print at some "discount" petrol stations that their petrol is adulterated with up to 10% ethanol, a common practice at some of the smaller independent petrol station chains ... now THAT some engines certainly don't like at all ...
for the sulphur I put in a bottle of fuel system cleaner into the fuel tank every 3 months or so to keep the lines and injectors clean ... -
You mean you pump at Mohawk?Originally posted by Fatum:hmmmm ... interesting .... in Canada I used to pump 91 mean for my wreck, until higher prices forced me down to 87, I don't see any noticeable difference actually ....
then I realised one day as I was reading the fine print at some "discount" petrol stations that their petrol is adulterated with up to 10% ethanol, a common practice at some of the smaller independent petrol station chains ... now THAT some engines certainly don't like at all ...
for the sulphur I put in a bottle of fuel system cleaner into the fuel tank every 3 months or so to keep the lines and injectors clean ...
Do you notice your fuel efficiency drop when you start pumping ethanol laced petrol.
My full tank drop to 350km from 425km when i use Mohawk Gas. -
I pump only at either Petro Canada or Shell now, my car's engine doesn't like any ethanol laced petrol at all, not only does fuel efficiency drop, the acceleration also slows down considerably ...Originally posted by Ponders:You mean you pump at Mohawk?
Do you notice your fuel efficiency drop when you start pumping ethanol laced petrol.
My full tank drop to 350km from 425km when i use Mohawk Gas.