Fuel octane
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RE: Fuel octane
ORIGINAL: spdrmns
well DThompson, you are once again saying what you read in the manual!!! Yes, i do have the 400 sumthin page honda service manual and to be honest the only thing i have looked in it for is operation limits, stock settings and tourqe vaules! when you can tell me why excatly your manual says 87 octane then i will give you some credit for learning somthing! I am talking from experiance!!! you know what octane i run in my race sled??? 110!!!! you know what octane i run in my race sled with my trail heads on?? 91! i honestly dont care what YOUR manual says! i am done in this thread becuase your mechanical know how is not were it should be to understand what i am talking about......
well DThompson, you are once again saying what you read in the manual!!! Yes, i do have the 400 sumthin page honda service manual and to be honest the only thing i have looked in it for is operation limits, stock settings and tourqe vaules! when you can tell me why excatly your manual says 87 octane then i will give you some credit for learning somthing! I am talking from experiance!!! you know what octane i run in my race sled??? 110!!!! you know what octane i run in my race sled with my trail heads on?? 91! i honestly dont care what YOUR manual says! i am done in this thread becuase your mechanical know how is not were it should be to understand what i am talking about......
Maybe you should have listened to all the rest of the people that know what they are talking about in the other thread about Octane in the F4i Section of the Forums.
I have had arguments with this spdrmns guy before about how he thinks he knows what he is talking about and he gives false statements. I swear I meet more idiots on this one website than I do on any other. They really come out of the woodwork in this one for some reason, and boy are they fierce when they "think" they know what they are talking about.
Have a nice day
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RE: Fuel octane
DThompson
The reason you run into so much opposition is probably because you take a piece of information and fill in the the blanks with your opinion. For example;
"Using a higher octane will cause carbon deposits because of incomplete combustion". I can only guess that you came up with this fact by assuming that the higher the octane the higher the resistance to burn and therefore it won't burn completely. This is false. Once the fuel mixture is ignited it will burn completely assuming the mixture is correct and the ignition system is in good working order. The octane rating of a fuel is a measure of the fuels ability to resist compression detonation, that's it, it has nothing to do with how it burns once the spark lights it.
Manufactures only state the minimum octane rating to be ran in their engines, there isn't a manufacture out there that states a maximum rating. Why, because it isn't relevant since it will do no harm or cause any driveability problems unlike running too low an octane fuel. If anything modern engines run as much timing advance as possible so running a higher octane fuel would increase the amount of advance that can be used before the point at which the engine starts pinging and the knock sensor sends a signal to the ECM to retard the timing. More advance = better acceleration.
You keep refering to the manual to back up what you post but all that is written in the manual is the minimum octane rating of fuel to be used it says nothing about the maximum. I'd like to see you find where it says " Warning! Do not exceed 87 octane fuel". Hell!, Your manual also states you should run 36psi in the front tire and 42psi in the rear but that's just a recomendation which I bet you don't follow so why are you so stuck on this octane thing?.
You also keep saying "it's not about being cheap it's what the manual says to use" we're not saying you don't use it because your cheap we're saying why not use higher octane it is cheap.
tcjayde
It must have been a long time since "the last time you checked" because a high compression engine is usually defined as one that has 10:1 compression or higher and that has been the norm for about 10 years for sportbikes and some cars. So since the factory "built my engine for high performance" with a compression ratio of 12:1 I'll go ahead and "use whatever fuel" I "feel is necessary". Thanks for giving me your approval now I'll be able to sleep at night.[sm=sleeping.gif]
I guess it's true what they say a little knowledge can be a dangerous thing.
Class dismissed.
The reason you run into so much opposition is probably because you take a piece of information and fill in the the blanks with your opinion. For example;
"Using a higher octane will cause carbon deposits because of incomplete combustion". I can only guess that you came up with this fact by assuming that the higher the octane the higher the resistance to burn and therefore it won't burn completely. This is false. Once the fuel mixture is ignited it will burn completely assuming the mixture is correct and the ignition system is in good working order. The octane rating of a fuel is a measure of the fuels ability to resist compression detonation, that's it, it has nothing to do with how it burns once the spark lights it.
Manufactures only state the minimum octane rating to be ran in their engines, there isn't a manufacture out there that states a maximum rating. Why, because it isn't relevant since it will do no harm or cause any driveability problems unlike running too low an octane fuel. If anything modern engines run as much timing advance as possible so running a higher octane fuel would increase the amount of advance that can be used before the point at which the engine starts pinging and the knock sensor sends a signal to the ECM to retard the timing. More advance = better acceleration.
You keep refering to the manual to back up what you post but all that is written in the manual is the minimum octane rating of fuel to be used it says nothing about the maximum. I'd like to see you find where it says " Warning! Do not exceed 87 octane fuel". Hell!, Your manual also states you should run 36psi in the front tire and 42psi in the rear but that's just a recomendation which I bet you don't follow so why are you so stuck on this octane thing?.
You also keep saying "it's not about being cheap it's what the manual says to use" we're not saying you don't use it because your cheap we're saying why not use higher octane it is cheap.
tcjayde
It must have been a long time since "the last time you checked" because a high compression engine is usually defined as one that has 10:1 compression or higher and that has been the norm for about 10 years for sportbikes and some cars. So since the factory "built my engine for high performance" with a compression ratio of 12:1 I'll go ahead and "use whatever fuel" I "feel is necessary". Thanks for giving me your approval now I'll be able to sleep at night.[sm=sleeping.gif]
I guess it's true what they say a little knowledge can be a dangerous thing.
Class dismissed.
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RE: Fuel octane
By the way DThompson, I just checked the other thread in the F4i section that you refered to and it looks like most of the posters are saying there is a decal on their bikes saying use 91.[sm=oopssign.gif]
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RE: Fuel octane
No they arent. I never read any that said there was a sticker on the side that said to use 91 octane The rest of them that you ignored apparently are saying that 87 octane is what you should use. And I never said anything about carbon deposits.
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RE: Fuel octane
DThompson, so you think i dont know what im talking about?!?!?! HA!!! lets not forget who thought slaming a car in drive is JUST LIKE clutchin up a wheelie! HA! + i never said you cant use 87 octane in your bike! and by all means, its your bike, do what you want! i am saying a high compression theoretically will run better on premium fuel! COMMON SENCE! canadianF4i explained it very well! AND its the same damn concept when i am talkin about my sled! COMPRESSION RATIO!!!! oh and i didnt learn from a book! i learned from rippin it apart and putting it back together again!!! you have NONE,0,ZIP,NOTA, NO expreiance in re-building a motor or working on one! your troubleshoting skills are that of a 10 year old! you know how i know this??! cause all you do is COPY AND PASTE FROM A MANUAL!!!!!!
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RE: Fuel octane
well how about this. Instead of you arguing with me like a baby. You state what you think in the best shape and form that you can and leave it at that. If you would explain everything to the full extent instead of just throwing bits and pieces in there than there wouldnt be any thing to say about it. Yet again another of your misshaps that could have been avoided. Which seems to be a reaccuring problem. The only thing you can say anymore is that I dont have skills or that I am copying and pasting things. Sorry but I think I know how to work on vehicles from experience. Given I dont work on drag cars but i do all my work on my own vehicles at home including the bike unless i need a tire balanced or something. And yes I have torn down and rebuilt engines before as well as trannys. You are creating false accusation as if you are all mighty powerful or something.
Pretty much your thoughts dont mean much to me.
Sorry I hurt your feelings.
As for the auto car and clutching thing. I was using it as an example of winding up the engine and dropping it in gear. I already said what was with that. You didnt pay attention then either. You just dont understand enough i guess.
Pretty much your thoughts dont mean much to me.
Sorry I hurt your feelings.
As for the auto car and clutching thing. I was using it as an example of winding up the engine and dropping it in gear. I already said what was with that. You didnt pay attention then either. You just dont understand enough i guess.
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From: Colorado, USA
RE: Fuel octane
DThompson, I know I probably shouldn't get involved, but I can't help it. What I get from what you are saying is that the factory figured out the best fuel to use in my bike? I'm sorry but I have to disagree with that. The factory figures out the minimum octane rating that needs to be run to stay away from detonation. So if they figured out what the minimum is, then why shouldn't I put something better in my bike? Also, it is commonly known that if a bike or car has above 10.0:1 compression then you need to run at least 91 octane fuel to get the best performance and stay away from detonation. Now if something has changed in the last couple years then please correct me, but I don't think anything has.
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RE: Fuel octane
DThompson
I owe you an appology you did not say high octane fuel causes carbon deposits specifically (that was someone else in another similiar thread) but you did say that they wouldn't burn completely which is the only cause of carbon deposits whether it be unburnt oil or fuel.
There is at least one guy stating he has the sticker and quick tally of who's using what breaks down to approx 2 using 89, 4 using 87 and 5 using 91+.
I also assumed you didn't know what you were talking about and only knew how to quote the manual, again I appologise I didn't realize you were a seasoned backyard mechanic.[sm=hail.gif]
Well I guess that trumps my over 12 years as a licenced automotive mechanic and 6 as a commercial transport mechanic and numerous certificates including emmissions diagnosing and repair. What was I thinking going to school and working in the trade for so long? I should have just bought a Haynes or Clymer manual and called it a day. [sm=yeahsmile.gif]
For the rest of you reading this I don't usually come down on someone who wants to learn or teach me and others something. It's just one of my pet peeves when someone states something as fact but doesn't understand why, can't explain why or can't back it up with anything more then so and so told me or that's what the owners manual says. Clymers manuals are designed to describe how to re and re parts they don't explain how it works. Owners manuals are just meant to be used as a quick referance ie what fuse goes where, how to start your bike. Neither replace having a good understanding of how a piece of equipment works.
I owe you an appology you did not say high octane fuel causes carbon deposits specifically (that was someone else in another similiar thread) but you did say that they wouldn't burn completely which is the only cause of carbon deposits whether it be unburnt oil or fuel.
There is at least one guy stating he has the sticker and quick tally of who's using what breaks down to approx 2 using 89, 4 using 87 and 5 using 91+.
I also assumed you didn't know what you were talking about and only knew how to quote the manual, again I appologise I didn't realize you were a seasoned backyard mechanic.[sm=hail.gif]
Well I guess that trumps my over 12 years as a licenced automotive mechanic and 6 as a commercial transport mechanic and numerous certificates including emmissions diagnosing and repair. What was I thinking going to school and working in the trade for so long? I should have just bought a Haynes or Clymer manual and called it a day. [sm=yeahsmile.gif]
For the rest of you reading this I don't usually come down on someone who wants to learn or teach me and others something. It's just one of my pet peeves when someone states something as fact but doesn't understand why, can't explain why or can't back it up with anything more then so and so told me or that's what the owners manual says. Clymers manuals are designed to describe how to re and re parts they don't explain how it works. Owners manuals are just meant to be used as a quick referance ie what fuse goes where, how to start your bike. Neither replace having a good understanding of how a piece of equipment works.
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RE: Fuel octane
theres more to what octane to run than compression. Ignition timing has just as much affect on detonation and such as octane rating does.
If your bike calls for 87/89/73/104, use whats called for OR higher. higher will not hurt, however it will not help either....without changes to ignition timing that a higher octane will allow you to do. Higher octane just has a higher resistance to detonation (pre-ignition), it does not contain a magical power-adder!
Using a higher octane than called for is absolutely useless unless you advance your ignition timing.
Using a lower octane will cause detonation and start eating away at your piston and cylinder head metals.
As the piston goes up in the bore the ignitino ignites the a/f mixture and starts the burn just before the piston reaches the top of its stroke. (keep in mind that there is no actual EXPLOSION happening in the cylinder, its all a controlled burn timed perfectly.) This starts the combustion process. The flame front actually starts to burn while the piston is moving up (BTDC Before Top Dead Center) but does not actually create "power" until the piston has reached the top of its stroke and begins to move down. Detonation, aka pre-ignition, is when the a/f mixture ignites while the piston is too far down the bore and before it starts its "power" stroke.
Lower octanes burn faster and higher octanes burn slower. Therefore, if you run an octane too low, detonation occurs and causes harm. Using a higher octane than needed will do absolutely nothing to help create more power.
Due to the higher octanes burning slower, you can advance the timing (18* BTDC as opposed to 14* BTDC for example) and allow the flame front to start to burn more efficiently as the a/f mixture is compressed and before it starts its downward "power" stroke.
Seems like my post kinda goes back and forth but I've done the best I could to describe why octanes function differently.
This concludes this session of octane discussion. Next session, we introduce BOOST and how it affects a/f ratios and octanes.
If your bike calls for 87/89/73/104, use whats called for OR higher. higher will not hurt, however it will not help either....without changes to ignition timing that a higher octane will allow you to do. Higher octane just has a higher resistance to detonation (pre-ignition), it does not contain a magical power-adder!
Using a higher octane than called for is absolutely useless unless you advance your ignition timing.
Using a lower octane will cause detonation and start eating away at your piston and cylinder head metals.
As the piston goes up in the bore the ignitino ignites the a/f mixture and starts the burn just before the piston reaches the top of its stroke. (keep in mind that there is no actual EXPLOSION happening in the cylinder, its all a controlled burn timed perfectly.) This starts the combustion process. The flame front actually starts to burn while the piston is moving up (BTDC Before Top Dead Center) but does not actually create "power" until the piston has reached the top of its stroke and begins to move down. Detonation, aka pre-ignition, is when the a/f mixture ignites while the piston is too far down the bore and before it starts its "power" stroke.
Lower octanes burn faster and higher octanes burn slower. Therefore, if you run an octane too low, detonation occurs and causes harm. Using a higher octane than needed will do absolutely nothing to help create more power.
Due to the higher octanes burning slower, you can advance the timing (18* BTDC as opposed to 14* BTDC for example) and allow the flame front to start to burn more efficiently as the a/f mixture is compressed and before it starts its downward "power" stroke.
Seems like my post kinda goes back and forth but I've done the best I could to describe why octanes function differently.
This concludes this session of octane discussion. Next session, we introduce BOOST and how it affects a/f ratios and octanes.
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RE: Fuel octane
im4u2nv81
You explained this very well, keep on spreading the good word[sm=grinangel.gif]. I would only change/add one thing though, instead of;
"Lower octanes burn faster and higher octanes burn slower."
I think it would be more accurate to say; lower octane fuels spontaneously combust (because of compression) at a lower ambient temp and higher octane fuels spontaneously combust at a higher ambient temp.
To sum it up, for those that are looking for the short version of this thread;
higher compression = higher heat = need for higher octane
more timing advance = higher octane needed
too low octane = bad
too high octane = not bad
im4u2nv81
Save me a seat for your next session on BOOST and how it affects A/F ratios and octanes
You explained this very well, keep on spreading the good word[sm=grinangel.gif]. I would only change/add one thing though, instead of;
"Lower octanes burn faster and higher octanes burn slower."
I think it would be more accurate to say; lower octane fuels spontaneously combust (because of compression) at a lower ambient temp and higher octane fuels spontaneously combust at a higher ambient temp.
To sum it up, for those that are looking for the short version of this thread;
higher compression = higher heat = need for higher octane
more timing advance = higher octane needed
too low octane = bad
too high octane = not bad
im4u2nv81
Save me a seat for your next session on BOOST and how it affects A/F ratios and octanes