87 Octane

outhouse said:

Nope, very slightly more, not less.

The higher the octane the slower the burn, the slower the burn, the piston is being pushed down for a bit longer resulting in more HP.

More then anything it is to stop the knocking in high compression engines due to abnormal combustion of low octane, [preignition]



But if you have sources like this please bring it.


Fuel Rating - Octane Comparison - Dyno Tests Graphs - Hot Rod Magazine

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It really all depends upon the state of tune that the engine comes from the factory with.

If the owners manual states that the engine is tuned to run on 95 RON or higher.
Then in all likelihood there's no real advantage (in terms of tune or power) with running the higher rated octane fuel.

Of course if one wants to preserve the cleanliness of the fuel system and combustion chamber/valve pocket area, then by all means run the higher octane fuel, which here in OZ also incorporates a higher dose of additives to help facilitate the long term benefits of a cleaner engine.
This is arguably the only real benefit to the higher octane stuff unless the engine has actually been retuned by somebody other than the manufacturer to "only run reliably" on the higher octane fuel.

Cool, thanks for all the info.
I have a Porsche and when I use anything less than 93 octane I can hear the engine ticking. So I know for sure that the octane number means something. However with the Ducati I was told by Bruce Meyers who was the person training all the Ducati techs in the US for Ducati that I should use 87 in the stock Pani because it would be the best performance for this bike. Read the same thing by LT Snyder. So that is why I put in 87 octane yesterday and I wheelied in 3rd gear still leaned over quite a bit coming out of a fast turn which really took me by surprise plus I felt the bike really accelerating so much better overall. Now it was quite a bit cooler than in November so the air density may have played a role as well. But my ... dyno likes 87 octane or the cool air or I was just on fire LOL.
Seriously, thanks for all the info.

turnone said:

Agree but keep in mind too low of octane can reduce fuel economy. So you may pay less per gallon but get less miles from that gallon.

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A lot can depend upon how long the fuel has been in the underground tanks as well.
Unleaded fuel doesn't last any where near as long in storage as the old leaded fuel used to.

Keep in mind that Bruce has always suggested using 87 octane that goes way back. This isn't suggesting or implying that Bruce is wrong, just sayin'.

Burn rate is somewhat associated with Octane rating, but not inextricably. An engineer at a local refinery had a friend do a bunch of dyno testing on Koch 110 and several other 'race fuels' VP etc. And most of the others required a couple degrees of advance over 91 octane (MON+RON /2) pump fuel while the Koch liked the same timing.

This discussion seems to accept that the ignition timing and AFR of the 1199 calibrations are actually close. They're not!! Sadly, not even close (AFRs for sure, I haven't done any fiddling with the ignition timing.)

When the AFRs are too rich you can handle much too much advance (that's how the Turbo guys keep their stuff from detonating to death when they don't adjust the timing.)

And, there are two catastrophic forms of aberrant combustion, one is pre-ignition and the other is detonation. Very different, but sometime occurring simultaneously.

Detonation is what we get when the octane rating is too low. Pre-detonation must be normal combustion which occurs before it pings.

Doug

Hi Doug
Nice of you to chime in. The 1198 you mapped 2-3 years back in Kentucky was a beast on the track. Just wanted to let you know that bike ran like a dream. I heard the Mitsubishi ECU is a nightmare to work with compared to the old ECUs. Is there going to be anytime soon the option to properly adjust the AFR like on the old bikes?
(Maybe the AFR and timing on my bike is so off that 87 fuel works best for it)

By the way, the 1198 made more horsepower after you mapped it than the 1199 from the factory.

moperfserv said:

Keep in mind that Bruce has always suggested using 87 octane that goes way back. This isn't suggesting or implying that Bruce is wrong, just sayin'.

Burn rate is somewhat associated with Octane rating, but not inextricably. An engineer at a local refinery had a friend do a bunch of dyno testing on Koch 110 and several other 'race fuels' VP etc. And most of the others required a couple degrees of advance over 91 octane (MON+RON /2) pump fuel while the Koch liked the same timing.

This discussion seems to accept that the ignition timing and AFR of the 1199 calibrations are actually close. They're not!! Sadly, not even close (AFRs for sure, I haven't done any fiddling with the ignition timing.)

When the AFRs are too rich you can handle much too much advance (that's how the Turbo guys keep their stuff from detonating to death when they don't adjust the timing.)

And, there are two catastrophic forms of aberrant combustion, one is pre-ignition and the other is detonation. Very different, but sometime occurring simultaneously.

Detonation is what we get when the octane rating is too low. Pre-detonation must be normal combustion which occurs before it pings.

Doug

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Superb.
Another great response

ducdom said:

Cool, thanks for all the info.
I have a Porsche and when I use anything less than 93 octane I can hear the engine ticking. So I know for sure that the octane number means something. However with the Ducati I was told by Bruce Meyers who was the person training all the Ducati techs in the US for Ducati that I should use 87 in the stock Pani because it would be the best performance for this bike. Read the same thing by LT Snyder. So that is why I put in 87 octane yesterday and I wheelied in 3rd gear still leaned over quite a bit coming out of a fast turn which really took me by surprise plus I felt the bike really accelerating so much better overall. Now it was quite a bit cooler than in November so the air density may have played a role as well. But my ... dyno likes 87 octane or the cool air or I was just on fire LOL.
Seriously, thanks for all the info.

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Only a dyno could say for sure, but I would say air temp was THE reason your bike felt faster. Likely would have felt just as fast running 91+ (RON + MON/2).

I can't imagine anyone's ... that is so finely tuned they could detect the very very slight power advantage of using 87 octane vs 91-93, assuming it's not causing damage, which I can't say for sure. Ducati USA recommends 90+ in USA.. The amount of substances mixed with the gas is tiny relative to the whole energy output of each unit.

I don't know if there is any knock sensor built into this bike, but if it doesn't you could be causing damage and not detect it. This thing makes enough vibrations and sound to cover up mild problems IMO.

I'll stick with 91+. You obviously can decide for yourself.

I am really learning a lot here.
To take this another step further.
So if I understand correctly. What happens with low octane fuel is that during the compression stroke the fuel/air mixture gets compressed and together with the heat of the engine it causes it to detonate too early during the upstroke and therefore causes force against the advancing piston resulting in knocking or pinging and engine damage. Proper ignition would start before TDC and then the explosion forms and hits the piston in its downstroke and creates downstroke force, with the proper ignition timing of course.
Pre-ignition is when the mixture gets ignited by some small superheated particle on the cylinder or piston surface. Which happens regardless of the amount of compression. So if I have a really slow burning fuel mixture of 87 octane that detonates during the compression but burns really slow it could hit the piston on its down stoke and then cause no pinging. Assuming that would be the case, how could that increase power over a higher octane mixture.

( Maybe since my timing of the engine is so off from the factory, using 87 octane with detonation creates a better timed engine than using 91 with the crappy timing curves from the factory. We all know that the ignition timing never was a strong point of the Ducati factory considering all the crappy torque and HP curves)

ducdom said:

I am really learning a lot here.
To take this another step further.
So if I understand correctly. What happens with low octane fuel is that during the compression stroke the fuel/air mixture gets compressed and together with the heat of the engine it causes it to detonate too early during the upstroke and therefore causes force against the advancing piston resulting in knocking or pinging and engine damage. Proper ignition would start before TDC and then the explosion forms and hits the piston in its downstroke and creates downstroke force, with the proper ignition timing of course.
Pre-ignition is when the mixture gets ignited by some small superheated particle on the cylinder or piston surface. Which happens regardless of the amount of compression. So if I have a really slow burning fuel mixture of 87 octane that detonates during the compression but burns really slow it could hit the piston on its down stoke and then cause no pinging. Assuming that would be the case, how could that increase power over a higher octane mixture.

( Maybe since my timing of the engine is so off from the factory, using 87 octane with detonation creates a better timed engine than using 91 with the crappy timing curves from the factory. We all know that the ignition timing never was a strong point of the Ducati factory considering all the crappy torque and HP curves)

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It seems as though you're confusing yourself a bit.
For a start, from what I'm reading is that you believe the lower octane fuel burns slower.
87 will burn quicker than 91 which burns quicker than 93.

The less volatile fuel will be used in a higher compression engine to help safely release more power potential through correct tuning without risking engine damage and or creating power robbing conditions during the combustion phase.

It's not simple.
There's a heap of variables that come into play other than compression(which is not a constant), such as initial timing, the timing advance curve, total ignition timing advance, valve timing, valve opening duration, total amount of valve opening, exhaust/inlet valve overlap, piston crown design, combustion chamber shape, etc etc etc, blah blah blah, ........ ........ .........

Thanks
87 fuel has less resistance to detonation than higher octane fuel. I understand that. But does that mean that is also burns faster? I am not sure resistance to detonation is actually the same as rate or speed of combustion. 87 octane fuel burns hotter and more complete than higher octane fuel. But does it burn faster?


Engines with high compression use higher octane due to its higher resistance to detonation and therefore they are safer to use in such engines. It is recommended to use higher Octane in carbon fouled engines to prevent pre-ignition because higher octane does emit less heat. A lot of these engine are carbon fouled because too high octane was run. But speed of combustion is not the reason we use higher octane levels in an engine.

turnone said:

Only a dyno could say for sure, but I would say air temp was THE reason your bike felt faster. Likely would have felt just as fast running 91+ (RON + MON/2).

I can't imagine anyone's ... that is so finely tuned they could detect the very very slight power advantage of using 87 octane vs 91-93, assuming it's not causing damage, which I can't say for sure. Ducati USA recommends 90+ in USA.. The amount of substances mixed with the gas is tiny relative to the whole energy output of each unit.

I don't know if there is any knock sensor built into this bike, but if it doesn't you could be causing damage and not detect it. This thing makes enough vibrations and sound to cover up mild problems IMO.

I'll stick with 91+. You obviously can decide for yourself.

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How the engine is running overall is a good indicator as to the suitability of a particular fuel for a given engine.

The butt dyno is quite good at determining that from an everyday perspective.

For example we have 2 main brands of fuel to choose from here in OZ.
They're BP and Shell.
Even though they may carry the same octane rating, they do burn differently because they're formulated differently. Shell is said to be a denser fuel.
If you're tuning with carburettors , jetting will end up being different for the 2 different brands, and the jetting for shell would indicate that it may well be denser.
Obviously fuel density will affect the running of an engine regardless of the jetting required.

Now one would assume that our DUCATI's would go better on the Shell fuel, seeing as DUCATI and Shell have a close partnership regarding lube oil design and fuel. Right?

Not necessarily.
From my personal experience and from talking with other people, the vast majority of consumers would rather use the BP fuel in their stock tuned engines.

I used to be a fan of the 98 RON fuel but eventually moved to the 95 RON fuel.
It wasn't out of economics.
It was driven by the desire to run the best fuel that actually improved rideability with the stock tunes. This has largely been validated by dyno runs showing peak power numbers even though I am chasing optimised rideability throughout the rev range. The differences in peak power are quite small though, and not the focus of my efforts.

In summary, one cannot discount the butt dyno.
After all, with EFI when one dyno tunes a bike, regardless of how good the read out looks on the computer. One still has to take it for a good test ride to verify that it's all good.
If during the real world test ride one detects some things that need tweaking then it's back to the dyno to sort it out.
The end result is virtually never what the computer shows you to be the best scenario.
Butt dyno rules.

Time for bed in California. Thanks gents at enlightening me a bit more about the subject. Beats watching some soap opera on TV

ducdom said:

Thanks
87 fuel has less resistance to detonation than higher octane fuel. I understand that. But does that mean that is also burns faster? I am not sure resistance to detonation is actually the same as rate or speed of combustion. 87 octane fuel burns hotter and more complete than higher octane fuel. But does it burn faster?


Engines with high compression use higher octane due to its higher resistance to detonation and therefore they are safer to use in such engines. It is recommended to use higher Octane in carbon fouled engines to prevent pre-ignition because higher octane does emit less heat. A lot of these engine are carbon fouled because too high octane was run. But speed of combustion is not the reason we use higher octane levels in an engine.

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I think we're talking about volatility. Volatility is the key word.

Carbon fouling can be, and usually is caused by a number of factors which aren't related to the octane rating of the fuel. At all.

It's really too complex to go on with on an internet forum. IMO.

There is not a forum dealing with internal combustion engines that hasn't delved into this subject. I am not near my bike, but is there a tag on them with the octane requirement? while he told me 89 worked, I am willing to give up a tad to run 91/92. Most stations have a tank of 87 and one of 91, 92 or 93 and blend the mid grades. I'd rather not trust them. Higher octane will never hurt and engine, while lower may.

Brad said:

I think we're talking about volatility. Volatility is the key word.

Carbon fouling can be, and usually is caused by a number of factors which aren't related to the octane rating of the fuel. At all.

It's really too complex to go on with on an internet forum. IMO.

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Brad, I think a really knowledgeable person should be able to explain us here on the forum all the things we addressed. I always found the professors who really knew what they were talking about could always explain the most complicated subject to anyone in a really short and simple manner.

Carbon buildup would increase compression therefore require higher octane.
Can't imagine much carbon buildup in a 2012 vehicle.

Brad said:

How the engine is running overall is a good indicator as to the suitability of a particular fuel for a given engine.

The butt dyno is quite good at determining that from an everyday perspective.
.....
In summary, one cannot discount the butt dyno.
After all, with EFI when one dyno tunes a bike, regardless of how good the read out looks on the computer. One still has to take it for a good test ride to verify that it's all good.
If during the real world test ride one detects some things that need tweaking then it's back to the dyno to sort it out.
The end result is virtually never what the computer shows you to be the best scenario.
Butt dyno rules.

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I can discredit the butt dyno in his situation where it was cooler out which affects power much more than the theoretical energy content between 91-93 octane gas and 87 octane.

I agree that riding gives the final decision but no ones ... can distinguish which factor makes the difference.

About Ducdom's post. Detonation doesn't necessarily occur before the spark event. The advancing pressure wall from the burn (not explosion) causes the cylinder pressure to increase ahead of it which can cause mixture in corners and too large squish areas to spontaneously ignite. That sends a shock wave through all of the fluid in the chamber and that is the 'ping' we hear (and frequently, don't hear.) That can cause the crystally erosion we see on pistons crowns and cylinder heads, in some cases.
Pre-ignition can be caused by too hot electrode on a spark plug. The results of this are melting of the piston and sometimes the heat causes detonation.

How do I know? I have examples of both.

My opinion aside of what octane to use, lets remember theres more than one type of octane rating in the world. Here in the USA we use the ((R+M)/2) method. Then theres the AKI Octane method, and some others I believe.

But seriously, who buys a $30,000 super bike and pinches $0.22/gallon in gasoline? Even MY cheap, frugal, stingy, (whatever you call me) ... wouldn't ever put a drop of anything under 91 R+m/2 octane in this bike.

I don't think this discussion has ever been about saving a few cents.
Rather it's been about the best performance.
Bruce Meyers has always advocated using 87 octane and he's about performance.