91 octane vs. 87: I am so dumb.

[Gryphon]

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Shell 91 = Good
Petro/Sunoco 94 = Baaaaaaad.
-Jamie M.

What he said...
Good 91 octane 'super' gas from Shell or Esso is the right stuff;
The Sunoco 94 is full of Ethanol.
Very unlikely anyone requires 94 octane anyway - many don't require even 91 (as has been mentioned).
Big cruisers often benefit more from 91 octane fuel than some sportbikes will, due to the nature of pre-ignition (detonation).
Nasty detonation will flourish in a heavily-loaded motor at low RPM.
Basically a problem in torque RPM range.
But little motors that wind way up to make horsepower do not encounter the same challenges...

I use the good stuff (91) in anything I ride - it's much safer in old bikes/bikes that may be out of tune, or when going on a road-trip anywhere, and in anything air-cooled (especially in very hot weather).
Highways speeds at lowish revs in top gear are a recipe for detonation! **
If you come to a long uphill, especially 2-up, you should probably downshift once...
Or maybe twice if running the 87, heheh.
Sure, maybe brand-new these bikes will run on 87 - but things get worse from then on.
(My 1987 with 80k KM, for example, gets only 91.)

Now, that said, some motors are built to run well on 87 - they're 'tractors' and nothing wrong with bike motors like that, they're good.
Someone was talking about "octane and high rpm torque", yes this is horsepower.
Torque x RPM = horsepower.
But in the real world, your bike will complain at low RPM.

**This is why it's not good to break-in new bikes on the highway, especially at steady revs at highway speeds...
You need to be up & down in revs, on & of the throttle, and not too-low RPMs on new bikes.
These are the same conditions under which your bike will not detonate (or minimized) on 87 octane fuel.

 

[rukus]

What he said...
Good 91 octane 'super' gas from Shell or Esso is the right stuff;
The Sunoco 94 is full of Ethanol.
Very unlikely anyone requires 94 octane anyway - many don't require even 91 (as has been mentioned).
Big cruisers often benefit more from 91 octane fuel than some sportbikes will, due to the nature of pre-ignition (detonation).
Nasty detonation will flourish in a heavily-loaded motor at low RPM.
Basically a problem in torque RPM range.
But little motors that wind way up to make horsepower do not encounter the same challenges...

I use the good stuff (91) in anything I ride - it's much safer in old bikes/bikes that may be out of tune, or when going on a road-trip anywhere, and in anything air-cooled (especially in very hot weather).
Highways speeds at lowish revs in top gear are a recipe for detonation! **
If you come to a long uphill, especially 2-up, you should probably downshift once...
Or maybe twice if running the 87, heheh.
Sure, maybe brand-new these bikes will run on 87 - but things get worse from then on.
(My 1987 with 80k KM, for example, gets only 91.)

Now, that said, some motors are built to run well on 87 - they're 'tractors' and nothing wrong with bike motors like that, they're good.
Someone was talking about "octane and high rpm torque", yes this is horsepower.
Torque x RPM = horsepower.
But in the real world, your bike will complain at low RPM.

**This is why it's not good to break-in new bikes on the highway, especially at steady revs at highway speeds...
You need to be up & down in revs, on & of the throttle, and not too-low RPMs on new bikes.
These are the same conditions under which your bike will not detonate (or minimized) on 87 octane fuel.

wtf?

 

[TMP]

Exactly it depends on what the engine is designed to run with I have to use premium in my 1198 because it needs it and was designed for it. Check the manual and use what is recomended many bikes do not need premium.

my 1098's manual says 95 RON which is equivalant to 89 OCT here. i suppose the 1198 is different but i dont notice any difference between the different octanes. actually i think i read a while back that lower octanes combust faster and the name given is more for marketing (premium, superior, V-power). the fuel combusts a fraction slower to account for higher compression. i maybe be wrong

 

[Scuba Steve]

my 1098's manual says 95 RON which is equivalant to 89 OCT here. i suppose the 1198 is different but i dont notice any difference between the different octanes. actually i think i read a while back that lower octanes combust faster and the name given is more for marketing (premium, superior, V-power). the fuel combusts a fraction slower to account for higher compression. i maybe be wrong

You have to watch Ducati used really bad plastic to make their fuel tanks and it is sensitive to softening with ethanol. There is a class action lawsuit about it in the US, V power is the only gas without ethanol at the moment.

 

[homme de fer]

One more thing, there is the assumption that 91 octane is somehow "better" than 89 or 87. You would be wrong. Octane rating only pertains to the fuel's ability to resist early detonation under higher compression. The idea that an engine will run better if you throw 91 or 94 into an engine rated for 87 octane is completely false. As a matter of fact, you may end up with less performance.

Why?

Use of a higher octane does not provide more power (unless the engine is designed for it). It does not "burn cleaner" or anything like that. In fact, it burns slower, and achieves a less complete burn, which can lead to carbon build up in the cylinder/valves (again, unless the engine is designed for it).

Want proof? Run your tank empty then throw in a liter of race fuel with triple digit octane and try to start it. Good luck with that.

 

[D23]

These octane threads never get old do they?

I'm not surprised that there are still people out there that think octane means HP since advertising works on the feeble minded.

No matter what anyone says people will still pump 91-94 into their bikes and get worse HP numbers but still be convinced it's better.

Some of you get it but.....

It's not even worth anyone's effort to try to explain it. Obviously every one of these stupid threads contain the right answer yet nobody learns anything from it.

Ignorance is bliss.

 

[TMP]

You have to watch Ducati used really bad plastic to make their fuel tanks and it is sensitive to softening with ethanol. There is a class action lawsuit about it in the US, V power is the only gas without ethanol at the moment.

*&^(*&en ducati. i have read that but no issues so far. maybe good or bad, not sure but the cap is not air tight and can hear fumes escaping. i plan on putting the shell gas in when storing.

 

[x86ect]

to the OP... is the 91 recommended, or required?
Will the ECU simply retard timing (to prevent knock)? If so, you may still be ok.

 

[homme de fer]

These octane threads never get old do they?

I'm not surprised that there are still people out there that think octane means HP since advertising works on the feeble minded.

No matter what anyone says people will still pump 91-94 into their bikes and get worse HP numbers but still be convinced it's better.

Some of you get it but.....

It's not even worth anyone's effort to try to explain it. Obviously every one of these stupid threads contain the right answer yet nobody learns anything from it.

Ignorance is bliss.

+1 billion

 

[Griffin]

You have to watch Ducati used really bad plastic to make their fuel tanks and it is sensitive to softening with ethanol. There is a class action lawsuit about it in the US, V power is the only gas without ethanol at the moment.

I understand that since 2007 all gasoline sold in ONtario MUSt contain at least 5% ethanol.

 

[rukus]

I understand that since 2007 all gasoline sold in ONtario MUSt contain at least 5% ethanol.

close, there must be 5% ethanol in the total of gasoline produced by a company. most have up to 10%. this is how sunoco provided 91oct with no ethanol.


Regulation 535/05

it is sensitive to softening with ethanol.

thats what some owners say, however it is not conclusive. there are reports of riders using solely non-ethanol fuel having the same problem. it seems to be an issue of heat and cheap plastic, not necessarily ethanol.

 

[invictus43]

to the OP... is the 91 recommended, or required?
Will the ECU simply retard timing (to prevent knock)? If so, you may still be ok.

Most motorcycles don't have knock sensors so there is no timing adjustment, unlike in cars. In a car you can actually see a HP difference with higher octane because of the ECU.

 

[invictus43]

Want proof? Run your tank empty then throw in a liter of race fuel with triple digit octane and try to start it. Good luck with that.

That may be true with race fuels, but between 87 and 91 pump gas, given the same ethanol content, you likely won't see any appreciable difference at all. Except in your wallet..

 

[Griffin]

close, there must be 5% ethanol in the total of gasoline produced by a company. most have up to 10%. this is how sunoco provided 91oct with no ethanol.


Regulation 535/05

Thanks for the info.

 

[imnothng]

close, there must be 5% ethanol in the total of gasoline produced by a company. most have up to 10%. this is how sunoco provided 91oct with no ethanol.


Regulation 535/05

interesting, then how do some Shell stations get away with it?

 

[SunnY S]

Bike magazine did a thorough test on a BMW S1000RR not that long ago.

They put it on a dyno, and filled the tank with 91 Shell Vpower. Then they completely drained the tank, and put in pricier 94 Octane. Then, they completely drained the tank, and put in expensive Race fuel (I think 110oct?), doing dyno tests after each fill.

Conclusion?

Save your money.

If anybody recalls, this article, please post further details, or I'll have to go through my mag stash and dig it up.

 

[invictus43]

wtf?

Actually, some of that is true. It's not just compression ratio that affects octane requirement. It can be affected by valve timing, combustion chamber design, piston design, cooling effectiveness. Often, as engines get older, the octane requirement can go up because of carbon desposits in the combustion chamber. So it's not complete nonsense really.

 

[invictus43]

Conclusion?

Save your money.

Honestly, who will feel the difference in the "seat of the pants dyno"? VERY small differences between 87 and 91 or 94. You're more likely to see it at idle or part throttle cruise.

 

[Ikan]

well, buddy's friends cousin told me that octane makes the bike have better torque at higher rpms. he also said that ethanol is bad because it can eat away gas tanks and clogs fuel injecting nozzles

Well my "buddy's friend's cousin's" sister's boyfriend's newfew's grandma said "Who gives a horse's ***? All ya need is a good heaping of oats and water for dat horse. =1 horsepower!


Seriously, the higher the octane # the slower the gasoline burns. However, deisel fuel works in the opposite direction. Detonation is the result of gasoline burning very fast and when this happens in an engine designed for higher octane fuel a hot spot will be generated which can cause pinging and go to the point of burning a hole in a piston's top.

 

[ride2rideagain]

I hear the Govt. is mandating ethanol conversion, V-Power will no longer be ethanol free soon. Anyone know more about this?

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