Who uses Super Unleaded on your NA?
01-10-2004, 05:47 PM
#46
Burning Brakes
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The reason why the ROW has higher octane ratings than the US is because they use RON (research octane number) whereas the US uses (RON + MON)/2 where MON is motor octane number.
RON- the research octane number is found under "research" conditions AKA slow compression of a very evenly distributed fuel air mixture. This slow compression is much more efficient thus making the fuel air mixture more resistant to detonation because it heats up more slowly. Also the more even distribution of air and fuel makes the mixture more resistant to detonation because the even mixture has no lean spots.
MON- the motor octane number is found under “motor” conditions AKA fast compression of an unevenly distributed fuel air mixture. This faster compression is much less efficient (don’t believe me look in a Thermodynamics book). This makes the fuel air mixture less resistant to detonation because it heats up more quickly verses the same compression at lower speed. Also the less even distribution of air and fuel makes the mixture less resistant to detonation because the less even mixture has some areas that are more lean than others.
These 2 factors cause fuels measured using RON standards to display higher resistance to detonation than the same fuel measured using MON standards.
Also our cars engines are much more accurately represented in MON test than RON test because the MON test is designed to simulate automotive reciprocating engines while the RON test is designed to test much slower turning reciprocating engines.
The real kicker is that some fuels can have the same MON and different RON. Or the same RON and different MON. For example two fuels could both have a RON of 98 but one could have a MON of 88 and the other could have a MON of 80. The difference is not usually this big but it definitely can be. This would mean that in europe both fuels would have and “octane” of 98 but in the use fuel 1 would have an octane of 93 while fuel 2 would have an octane of 89. Thus meaning that in real world conditions which are your engine AKA your “motor” the first fuel would have better resistance to detonation than the second.
U.S. people look at the pump next time you are pumping gas you will see that the pump octane is measured using (RON+MON)/2.
John
RON- the research octane number is found under "research" conditions AKA slow compression of a very evenly distributed fuel air mixture. This slow compression is much more efficient thus making the fuel air mixture more resistant to detonation because it heats up more slowly. Also the more even distribution of air and fuel makes the mixture more resistant to detonation because the even mixture has no lean spots.
MON- the motor octane number is found under “motor” conditions AKA fast compression of an unevenly distributed fuel air mixture. This faster compression is much less efficient (don’t believe me look in a Thermodynamics book). This makes the fuel air mixture less resistant to detonation because it heats up more quickly verses the same compression at lower speed. Also the less even distribution of air and fuel makes the mixture less resistant to detonation because the less even mixture has some areas that are more lean than others.
These 2 factors cause fuels measured using RON standards to display higher resistance to detonation than the same fuel measured using MON standards.
Also our cars engines are much more accurately represented in MON test than RON test because the MON test is designed to simulate automotive reciprocating engines while the RON test is designed to test much slower turning reciprocating engines.
The real kicker is that some fuels can have the same MON and different RON. Or the same RON and different MON. For example two fuels could both have a RON of 98 but one could have a MON of 88 and the other could have a MON of 80. The difference is not usually this big but it definitely can be. This would mean that in europe both fuels would have and “octane” of 98 but in the use fuel 1 would have an octane of 93 while fuel 2 would have an octane of 89. Thus meaning that in real world conditions which are your engine AKA your “motor” the first fuel would have better resistance to detonation than the second.
U.S. people look at the pump next time you are pumping gas you will see that the pump octane is measured using (RON+MON)/2.
John
01-10-2004, 08:54 PM
#47
Nordschleife Master
Originally posted by 97xray
Maybe it IS in my head, but it's in my ears too;
I heard knocking the one and only time I put 87 in the Euro.
Since then, under the greatest loads I could give the engine - and with 93 octane - not a sound but the good stuff from the engine.
So, yeah, I guess it "could" be in my head, but the >10:1 compression does seem to notice lower octane.
Maybe it IS in my head, but it's in my ears too;
I heard knocking the one and only time I put 87 in the Euro.
Since then, under the greatest loads I could give the engine - and with 93 octane - not a sound but the good stuff from the engine.
So, yeah, I guess it "could" be in my head, but the >10:1 compression does seem to notice lower octane.
01-10-2004, 10:10 PM
#48
Racer
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I always thought that octane rating or RON rating would have to be an international standard.
An extract from a fuel company website states:
OCTANE RATING
Octane number is a measure of a fuel's ability to resist knock. The octane requirement of an engine varies with compression ratio, geometrical and mechanical considerations and operating conditions. The higher the octane number the greater the resistance to knock.
RON
stands for Research Octane Number and is measured using a laboratory test engine. It is standard industry practice to differentiate grades of gasoline on the basis of their RON.
It doesn't make sense to have American fuel standards different to Australian or European standards. Why should your 93 be equivalent to every one else's 98
An extract from a fuel company website states:
OCTANE RATING
Octane number is a measure of a fuel's ability to resist knock. The octane requirement of an engine varies with compression ratio, geometrical and mechanical considerations and operating conditions. The higher the octane number the greater the resistance to knock.
RON
stands for Research Octane Number and is measured using a laboratory test engine. It is standard industry practice to differentiate grades of gasoline on the basis of their RON.
It doesn't make sense to have American fuel standards different to Australian or European standards. Why should your 93 be equivalent to every one else's 98
01-11-2004, 02:00 PM
#50
Three Wheelin'
Originally posted by PCMAX
It doesn't make sense to have American fuel standards different to Australian or European standards. Why should your 93 be equivalent to every one else's 98
It doesn't make sense to have American fuel standards different to Australian or European standards. Why should your 93 be equivalent to every one else's 98
The anti-knock index was developed to incorporate results from both of these tests, and is defined as: AKI = (RON + MON)/2 This is the value that is posted on North American pumps. I wonder why fuel suppliers in backwards parts of the world, such as Europe and Australia, don't adopt it, since it incorporates more testing and information.
