what kind of gas?
#41
07-04-2007, 09:21 PM
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RE: what kind of gas?
ORIGINAL: ChanCBR
Octane is a hydrocarbon having 8 single-bonded carbons. Basically when you get a higher octane you get more combustion and a high resistance like Jaybird said, so it will burn hotter. Thus cleaner. And earlier I believe someone said that a higher octane could cause knocking, although this is possible, I do not believe it is likely (at least in our sportbikes) since the PURPOSE of octane is to PREVENT knocking. Just my two cents.
Octane is a hydrocarbon having 8 single-bonded carbons. Basically when you get a higher octane you get more combustion and a high resistance like Jaybird said, so it will burn hotter. Thus cleaner. And earlier I believe someone said that a higher octane could cause knocking, although this is possible, I do not believe it is likely (at least in our sportbikes) since the PURPOSE of octane is to PREVENT knocking. Just my two cents.
#43
07-06-2007, 09:22 AM
RE: what kind of gas?
ORIGINAL: 65ShelbyClone
I really have never seen quite so much misunderstanding of fuel chemistry in one place before. Some posters have it right, but the majority don't...not even close.
Going for most recent, diesel fuel does not have a "good" octane rating. In fact, it has an octane rating of about 15. Yes, 15. Diesel instead has a "cetane" rating. Since diesel isn't used in gasoline engines, the cetane rating is irrelevant to us. Diesel will cause bad pinging in a spark ignition engine if mixed with gas. It won't even work if used alone.
"Octane" is in fact a hydrocarbon used as a baseline rating to describe a fuel's resistance to autoignition or knock in a spark ignition engine. Autoignition can be caused by lots of boost, lots of compression, oil contamination like that necessary of a 2-stroke, or all the above plus many other factors. Heptane is the antithesis of iso-octane and has an octane rating of 0.
- High octane fuel will not burn "hotter." Did you know that methanol has a motor octane of about 115, yet little more than half the BTU content of gasoline? Compressed natural gas has an octane rating of about 130, but 1/4 the energy content by weight of gasoline. Pump gas has a negligible difference of energy content between the grades.
- The "octane" rating of fuel often has nothing to do with how much actual octane(the hydrocarbon) is in the fuel, therefore the octane rating is independent of the fuel's specific energy content.
The bottom line is that the F4i's ability to run on 87 R+M/2 octane fuel shows how conservative Honda and/or Keihin was with the ignition advance curve. This is especially significant considering there is no knock sensor. Another aspect of being able to run 87 fuel through a 12:1 engine is the relatively high rpm. There is simply less time for the necessary chemical and thermodynamic reactions to take place in the cylinder. An efficient chamber desing also helps. I suspect that if Honda had taken full advantage of their design, none of us would be able to run anything less than 94-96 fuel.
Hopefully I didn't offend anyone too much. There are volumes that could be written on petroleum chemistry, but it's getting late and I'm getting fuzzy headed.
I really have never seen quite so much misunderstanding of fuel chemistry in one place before. Some posters have it right, but the majority don't...not even close.
Going for most recent, diesel fuel does not have a "good" octane rating. In fact, it has an octane rating of about 15. Yes, 15. Diesel instead has a "cetane" rating. Since diesel isn't used in gasoline engines, the cetane rating is irrelevant to us. Diesel will cause bad pinging in a spark ignition engine if mixed with gas. It won't even work if used alone.
"Octane" is in fact a hydrocarbon used as a baseline rating to describe a fuel's resistance to autoignition or knock in a spark ignition engine. Autoignition can be caused by lots of boost, lots of compression, oil contamination like that necessary of a 2-stroke, or all the above plus many other factors. Heptane is the antithesis of iso-octane and has an octane rating of 0.
- High octane fuel will not burn "hotter." Did you know that methanol has a motor octane of about 115, yet little more than half the BTU content of gasoline? Compressed natural gas has an octane rating of about 130, but 1/4 the energy content by weight of gasoline. Pump gas has a negligible difference of energy content between the grades.
- The "octane" rating of fuel often has nothing to do with how much actual octane(the hydrocarbon) is in the fuel, therefore the octane rating is independent of the fuel's specific energy content.
The bottom line is that the F4i's ability to run on 87 R+M/2 octane fuel shows how conservative Honda and/or Keihin was with the ignition advance curve. This is especially significant considering there is no knock sensor. Another aspect of being able to run 87 fuel through a 12:1 engine is the relatively high rpm. There is simply less time for the necessary chemical and thermodynamic reactions to take place in the cylinder. An efficient chamber desing also helps. I suspect that if Honda had taken full advantage of their design, none of us would be able to run anything less than 94-96 fuel.
Hopefully I didn't offend anyone too much. There are volumes that could be written on petroleum chemistry, but it's getting late and I'm getting fuzzy headed.
j/k...
and yes I can feel a difference. But then again I don't ride it on the street
#45
07-06-2007, 11:17 AM
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#46
07-06-2007, 11:21 AM
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#48
07-06-2007, 03:48 PM
RE: what kind of gas?
ORIGINAL: 65ShelbyClone
Let the ignoarance die wigth the ignorant, right? [sm=smiley2.gif]
Let the ignoarance die wigth the ignorant, right? [sm=smiley2.gif]
see voodoo's post above...muahahhaah
it's good stuff when you back the claims with engineering facts, etc...and not..."well...i think it shoud use this because it's high compression, blah blah blah..."
#49
07-06-2007, 04:24 PM
RE: what kind of gas?
there is a wide spread notion that higher octane = faster no questions asked.
This gets reinforced in movies and video games. I think there is a game called'high octane'.
It's natural for someone that doesn't know the science behind it to jump to that conclusion.
I admit when I first got my bike I thaught putting high octane in was better because someone told me it was.
This gets reinforced in movies and video games. I think there is a game called'high octane'.
It's natural for someone that doesn't know the science behind it to jump to that conclusion.
I admit when I first got my bike I thaught putting high octane in was better because someone told me it was.
#50
07-06-2007, 07:59 PM
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RE: what kind of gas?
thing about all this, dont put a higher octane in ur bike if there isnt a need, if ur gonna be racing ur bike on tracks days then get the higer octane, less of a chance of knocking and let it be easier for the fuel to burn. i run 89-91 round town and 100-110 track days