Better gas mileage with 89 octane!

[IanFrancisco]

Well, I thought it was a fluke, but after running three tanks of mid-grade 89 octane unleaded, I'm sure I'm averaging 60 mpg where I used to average about 57mpg on 87 octane. Anybody else had a similar experience? I switched because of the heat wave causing some high oil temps and rattling if the throttle was opened more than halfway at revs under 5k. The 89 octane fixed the rattling but the extra 3mpg was an unexpected bonus.

 

[Jethro]

I find my bike likes the 89 octane better as well. Not sure how much it affects my mileage, but the machine seems to sound and pull better with the 89.

 

[Hoomgar]

I have confirmed the same thing in several gas burning engines of mine over the years. If your having top end issues or pre detonation issues and you run a higher octane fuel to quiet the engine down then the improved economy comes along for the ride since the engine is now running better.

 

[Tarbash 27]

I ALWAYS USE 93 OCTANE. I THINK ITS RECOMENDED FOR MY 1979 GS750L. I USE 93 IN EVERYTHING, MY TRUCK, DIRTBIKE, LAWNMOWER, WEEDWACKER. I SOMETIMES PUT 110 OCTANE IN MY GS AND MAN, ITS AN ANIMAL, THERES DEFINATELY LIKE A 10-15 HORSEPOWER GAIN. AND IS SMELLS SWEAT TOO. TOO BAD ITS 5.99 A GALLON.

 

[BriTXbike]

Where in the HE** do you get 110 Octane? Are you just using a boast added to the 93?

 

[mixongw]

I ALWAYS USE 93 OCTANE. I THINK ITS RECOMENDED FOR MY 1979 GS750L. I USE 93 IN EVERYTHING, MY TRUCK, DIRTBIKE, LAWNMOWER, WEEDWACKER. I SOMETIMES PUT 110 OCTANE IN MY GS AND MAN, ITS AN ANIMAL, THERES DEFINATELY LIKE A 10-15 HORSEPOWER GAIN. AND IS SMELLS SWEAT TOO. TOO BAD ITS 5.99 A GALLON.

Just to be technical... and a pain in the butt... There is no such thing as 110 octane.

:wink:

 

[ringo00]

I use 89 all the time and my 79 750L runs great on that. I tried to use 87 once and it didn't like that too well.

And yes there is 110 octane gas. The gas station near my local dirt race track sells it as race fuel. I couldn't afford to run it in my bike though. It should never cost me more than $10 for a tank of gas.

 

[mixongw]

I use 89 all the time and my 79 750L runs great on that. I tried to use 87 once and it didn't like that too well.

And yes there is 110 octane gas. The gas station near my local dirt race track sells it as race fuel. I couldn't afford to run it in my bike though. It should never cost me more than $10 for a tank of gas.

There is no such thing as a 110% octane to heptane ratio. The fuel may have a "performance rating" of 110 but not octane. 87 octane gasoline is a mixture of 87% octane and the remaining 13% is usually heptane or other hydrocarbons with a shorter carbon chain or methanol.

 

[mixongw]

I use 89 all the time and my 79 750L runs great on that. I tried to use 87 once and it didn't like that too well.

And yes there is 110 octane gas. The gas station near my local dirt race track sells it as race fuel. I couldn't afford to run it in my bike though. It should never cost me more than $10 for a tank of gas.

There is no such thing as a 110% octane to heptane ratio. The fuel may have a "performance rating" of 110 but not octane. 87 octane gasoline is a mixture of 87% octane and the remaining 13% is usually heptane or other hydrocarbons with a shorter carbon chain or methanol.

 

[mixongw]

I use 89 all the time and my 79 750L runs great on that. I tried to use 87 once and it didn't like that too well.

And yes there is 110 octane gas. The gas station near my local dirt race track sells it as race fuel. I couldn't afford to run it in my bike though. It should never cost me more than $10 for a tank of gas.

There is no such thing as a 110% octane to heptane ratio. The fuel may have a "performance rating" of 110 but not octane. 87 octane gasoline is a mixture of 87% octane and the remaining 13% is usually heptane or other hydrocarbons with a shorter carbon chain or methanol.

 

[mixongw]

Sorry about the multiple posts. Blame it on Microsoft.

 

[BigMattyD]

The highest Octane I can find is 100LL (aviation gas) at the local airport. I can't help but think it costs over five dollars a gallon now. The last time I went flying, about three years ago, it was hovering around 2.20 to 2.50/gal.

Matt

 

[GARYEIN1]

BETTER GAS WITH 89 OCTANE

BETTER GAS WITH 89 OCTANE

WE USED TO HAVE A GAS STATION NEAR ME THAT HAD 100 OCTANE
BUT THAT WAS RUNNING 3.25/GAL WHEN GAS WAS ONLY 1.50-1.75
A GALLON
THEY STOPPED SELLING IT ANYMORE

AS FOR THE BIKE I USUALLY TRY TO RUN ONE TANK OF HIGHTEST TO
3 TANKS REGULAR

AVERAGE 44-51 PER GAL

85 GS550L

 

[duaneage]

Nothing gets em going like an octane thread. Rumor has it someone quit the GS resources over a flaming post about it.

Definately better performance on 93 for my bike. Running the same route everyday on low test I noticed a big difference in mileage, idle (especially in hot weather) and no more pinging when I went back to decent gas.

But until the porky oil companies and Our Friends the Saudis see a decrease in gallons sold we are going to pay through the nose for Super. Personally I don't mind paying 80 cents a tank more for better fuel. My cars have computers that adjust for cheap gas but the GS does not.

And I give thanks for the lack of computer controls it has.

 

[AOD]

Everyone has their own opinion on it. I use 93 octane generally unless I can't get it. The bike runs fine on any octane generally.

As for the 110 octane adding 10-15 horsepower...that is a lie. Octane alone will not add any power, only advancing the timing and raising the compression ratio that requires the higher octane fuel (to burn slower) will raise horsepower.

~Adam

 

[aRs3N1c42]

Here's an article about octane
http://auto.howstuffworks.com/question90.htm

Notice where it says "or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane". Since the refining process of crude oil cannot completely separate all the hydrocarbons into pure octane and pure heptane. Gasoline typically is a blend of many different hydrocarbons, alcohols, detergents and solvents to keep your engine clean and running well. The Octane rating on the pump is more often a comparison of the gasoline's performance to an actual octane/heptane solution produced in a laboratory.

My Organic chemistry professor in college explained all this to us, but since it was a 9:00 class, I wasn't completely awake most of the time. And since I never took great notes, I could be wrong. I'm still reading the articles on howstuffworks.com. I may post back with an update... 8)

 

[Poot]

I also prefer the 89 octane, over 87 , and 91. I've used the 93/94 but only when cruising at high speeds for long durations.


91 octane seems to jumpy, and 87 octane doesnt seem to make the engine as smooth as possible.

at least for my 850



poot

 

[DaveDanger]

Gonna add my 2 cents worth here as well To be understood is that aviation fuel is not accurately graded by octane rating, it is a performance rating. Nevertheless, it does what it does rather well. I will refer to "octane" here because that is what the fuel trucks are labelled as, and what it's called in the industry.
Aviation gasoline can be gotten in ratings as high as 130 Octane. The typical stuff obtained at the local airport will almost always be what is referred to as 100LL, it has a beautiful sky blue color. For aircraft usage, it really is "low lead" fuel. For automotive use, it has more lead than the fattest pencil ever pulled from inside your 3-ring binder at school. The 130 octane grade is refined in limited quantities anymore, but is used almost exclusively by the racing and aerobatic aircraft crowd. It has a deep purple color. Aviation 87 octane is almost unheard of anymore, causing a whole slew of engine problems due to the lubricant properties that are no longer provided... but that's a whole 'nother post on a different board I make no claim to exactly what the refining techniques that are used and exactly how the actual octane of avgas compares to autogas, but every dirt-tracker in the country can't be too far wrong when they cue up their 55 gallon drums at the gate to the local airport fuel farm on friday afternoons. In general, I have rather good access to Avgas in my daily grind, (I occasionally have to drain an aircraft fuel cell to perform maintenance and not many owners want the fuel pumped back into the plane after its been stored in just any old 55 gallon drum... Is it my fault that I keep very clean plastic drums around? I'm not gonna argue with them!) and frequently will filter a gallon or two into the bike's tank before I head to the local Saudi fuel outlet. The mixture of my 100LL and the regular 87 from the pump provides me a rather nice acceleration, lack of ping under almost any load, and just seems to kick me in the butt a tad harder than when it's plain 87. That may be my tiny mind wanting to justify the effort I went to to accomplish the goal. I do try to avoid going above a 50/50 mix of Avgas to autogas, just because it seems to run a bit hotter, idle faster and in general reaches a point of diminishing returns. During WWI, it was discovered that you can add a chemical called tetraethyl lead (TEL) to gasoline and significantly improve its octane rating above the octane/heptane combination. Cheaper grades of gasoline could be made usable by adding TEL. This led to the widespread use of "ethyl" or "leaded" gasoline. When lead was banned, gasoline got more expensive because refineries could not boost the octane ratings of cheaper grades any more. Airplanes are still allowed to use leaded gasoline (known as AvGas), and octane ratings of 100 or more are commonly used in super-high-performance piston airplane engines. In the case of AvGas, 100 is the gasoline's performance rating, not the percentage of actual octane in the gas. The addition of TEL boosts the compression level of the gasoline -- it doesn't add more octane.

 

[Buffalo Breath]

GaS

GaS

Silly Boyz, I thouht every one on two wheels ran nitro, oh yea it will give you a horse power boost with out more compression or boring, but the mileage really sucks, AHHHH I love the smell of Nitro in the morning!!!

 

[Clone]

Speaking only about my bike:
Premium 92or93 depending on the station = worst milage
Mid-grade 89 usually run get in the mid 40s
Regular 87 run once in a while when I fill up in the boons = best milage 46 or more
But I usually am riding in temperatures below what you get in the states, a nice day is 20-25C, most days 15-20C.

Reading "how stuff works" I get the impression that a lower flash point would mean that a fuel burns faster,
so 87 should burn better than 89, 89 better than 93
Do I have that right?
Then shouldn't 87 pack more power than 93?