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Higher octane = More power?
32 posts · Started by pingvin · 26 Dec 2008
Post 2 by chip,
#2We don't go near optimax for bikes in Australia. Fouls the plugs.
I find that BP Ultimate 98 RON is the bees knees.
I find that BP Ultimate 98 RON is the bees knees.
Post 3 by Leonidas,
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Post 4 by cjc,
#4+1
That's my understanding based on articles I've read.
(And Leonidas' English is better than most native speakers).
That's my understanding based on articles I've read.
(And Leonidas' English is better than most native speakers).
Post 5 by cjc,
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Post 6 by SuperDuke-DK,
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Post 7 by wrebitup,
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Post 8 by Schnauzer,
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Post 9 by Zenbiker,
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Post 10 by TC's SD,
#1098 RON has a lower calorific value than 95 RON & that means less power. Run your SD on 95.
Described
Described
Post 11 by Motohooligan,
#11Unable to resist the sick urge to further muddy the waters, consider the correct statements made that a higher octane rating means that the fuel mixture is more difficult to ignite, making it less prone to detonation in high compression or high rpm applications.
However (and yes, Virginia, there is always a 'however').
As rpm increases, dwell time for the flame front to propagate decreases. Unless the engine is designed with enough spark advance to compensate for the later ignition/slower burn of higher octane fuels, the high octane cocktail can and will cause a loss of power, and unburnt fuel exits the exhaust ports in the form of raw fuel vapor, increasing the afterfire effect we all know and love. Stop and do the math; using 8K rpm as a nice even number that divides well into 4 stroke math, there are 2000 ignition cycles per minute, or one every (60 seconds divided by 2000 cycles per second) 0.03 seconds, of which let's assume that each cycle only has 20 degrees of actual combustion (Joe, jump in and help here), leaving only 0.0017 (that's 17 ten thousandths of a second) for the spark to overcome the charge density, ignite the fuel, and the flame front to propagate across the broad plateau of an oversquare large bore v-twin piston.
Shite.
SO:
Hi octane fuel may or may not make your bike run better; it certainly can make it run worse, although the effect is not as damaging as running too low an octane. Detonation, as we all know, is a bad, bad thing, and will hole your pistons and bend your con rods, not to mention make observers leer disapprovingly at the sounds emanating from your steed which now sounds like a cheap Russian copy of a WWII BMW burning kerosene.
In the states, I run at least 91 if not 93 RON rated fuel; higher octanes are only available as race fuel which is illegal to use on the highway, and as the long winded diatribe above outlines, will only add performance owing to the drastically reduced weight of your wallet
Happy New Year to all!
However (and yes, Virginia, there is always a 'however').
As rpm increases, dwell time for the flame front to propagate decreases. Unless the engine is designed with enough spark advance to compensate for the later ignition/slower burn of higher octane fuels, the high octane cocktail can and will cause a loss of power, and unburnt fuel exits the exhaust ports in the form of raw fuel vapor, increasing the afterfire effect we all know and love. Stop and do the math; using 8K rpm as a nice even number that divides well into 4 stroke math, there are 2000 ignition cycles per minute, or one every (60 seconds divided by 2000 cycles per second) 0.03 seconds, of which let's assume that each cycle only has 20 degrees of actual combustion (Joe, jump in and help here), leaving only 0.0017 (that's 17 ten thousandths of a second) for the spark to overcome the charge density, ignite the fuel, and the flame front to propagate across the broad plateau of an oversquare large bore v-twin piston.
Shite.
SO:
Hi octane fuel may or may not make your bike run better; it certainly can make it run worse, although the effect is not as damaging as running too low an octane. Detonation, as we all know, is a bad, bad thing, and will hole your pistons and bend your con rods, not to mention make observers leer disapprovingly at the sounds emanating from your steed which now sounds like a cheap Russian copy of a WWII BMW burning kerosene.
In the states, I run at least 91 if not 93 RON rated fuel; higher octanes are only available as race fuel which is illegal to use on the highway, and as the long winded diatribe above outlines, will only add performance owing to the drastically reduced weight of your wallet
Happy New Year to all!
Post 12 by Pig Benis,
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Post 13 by wrebitup,
#13The supercharged and turbo applications will gain hp significantly from higher octane fuel.
On these applications timing must be reduced to eliminate detonation, therefore to add horsepower you must add timing in conjunction with hotter fuel.
My procharged 5 litre mustang went from 413 rwhp to 449 rwhp just by adding timing to the already retarded initial setting. Timing can only be added married to some hotter fuel.
Car manufacturers use knock sensors which sense detonation and therefore pull out timing which reduces horsepower.
This thread has good reading/smart members we have!
On these applications timing must be reduced to eliminate detonation, therefore to add horsepower you must add timing in conjunction with hotter fuel.
My procharged 5 litre mustang went from 413 rwhp to 449 rwhp just by adding timing to the already retarded initial setting. Timing can only be added married to some hotter fuel.
Car manufacturers use knock sensors which sense detonation and therefore pull out timing which reduces horsepower.
This thread has good reading/smart members we have!
Post 14 by lobster,
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Post 15 by Zenbiker,
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Post 16 by wrebitup,
#16the OG has spoken (Motohooligan!!)..... break it down my Brother!!! geet up on yer bad self!! he be the doo wit de DOPE!
http://en.wikipedia.org/wiki/The_stig
http://en.wikipedia.org/wiki/The_stig
Post 17 by leederman,
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Post 18 by pingvin,
#18Well, I've tried Optimax a few times in a few different vehicles including a twin turboed Mitsi 3000Gt and frankly noticed bugger all difference. Now that said, all the vehicles (including the 300Gt) are set up to run 95 octane, so I suspect that's your answer. If the vehicle is set for 95 octane sticking 98 or 99 in it will do nothing other than lighten your wallet. However, if your motor is set up to run hotter fuel using lower octane stuff may indeed induce knock and damage it. But as far as the SD is concerned its bog standard 95 octane every time for me!
Post 19 by lobster,
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Post 20 by Motohooligan,
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