GS Aventure Regular Gas?

[pjones]

I've read that the GSA has the ability of running on low octane regular gas (some type of switch or sensor?), but the owner's manual doesn't mention it. Maybe this feature came out after my '02 was built. Any knowledge of this? I want to run on the lowest octane I can without causing pinging under load.

Paul
'02 GSA

[PacWestGS]

Paul, if you're just cheap? :nyah buy regular gas and run it. US gas is sufficient to run your bike under most all conditions. You will lose some performance (questionable by quite a few readers here) :blah if you actually hear pinging (pre-ignition) go up to mid-grade. Most of us myself included paid $XX,XXX for a bike and an extra $1.00 per tank fill doesn't seem extravagant, for Luv'n my baby.

Yes, your GS Adventure has a dual circuit built into the Motronics unit that will adjust your delivery system, but that really only matters if you are in Mexico, Africa, or Mongolia where the octane level may be somewhere in the low 80's or something.

Have fun and don't be a cheap guy, it's only $0.20 more a gallon times FIVE.

Russ

[PUDGYPAINTGUY]

X 8 in an Adventure...lol

[PacWestGS]

X 8 in an Adventure...lol

Yeah gee I must be tired or something $1.60 :nyah

[cruisin]

but why do it? On both of my oilheads, the decrease in fuel efficiency when using a lower grade gas is so great that it actually costs me as much or money per mile to operate as when using premium. Case-in-point; on a jaunt into eastern NM a few years ago, the only grade I could find in Roy was 84 octane. The cruiser had been getting right around 48mpg all day until I filled it with that gas; then it dropped to 38mpg. If you are doing it when using the "adventure" on and adventure and the only gas available is lower grade, that is one thing. But to do it to save money is most likely counter-productive. :banghead

[bmwmick]

I've read that the GSA has the ability of running on low octane regular gas (some type of switch or sensor?), but the owner's manual doesn't mention it. Maybe this feature came out after my '02 was built. Any knowledge of this? I want to run on the lowest octane I can without causing pinging under load.

Paul
'02 GSA

Paul,
It's called a "low octane plug" and replaces the normal CCP in the center of the fuse box. Here is how it's wired:
Pins 86,87,30 connected.
http://www.advrider.com/forums/showthread.php?t=8776
http://www.advrider.com/forums/attachment.php?attachmentid=9289&stc=1&d=1036208244

[PUDGYPAINTGUY]

Yeah gee I must be tired or something $1.60 :nyah


hehehehehe

[BubbaZanetti]

i usually run 93 to keep the engine clean, where i go its only 2 cents more than 91, comes out of its own hose (as opposed to the shared hose for 87,89,91) and is still cheaper than the 91 at most places. the dollar or two extra it costs me a week seems worth it..............

[jacco]

but why do it? On both of my oilheads, the decrease in fuel efficiency when using a lower grade gas is so great that it actually costs me as much or money per mile to operate as when using premium.

This is strange. Low octane gas actually contains LESS stuff that DOESN'T burn, so hypothetically you should get more energy out per gallon. (Note the word hypothetically...) I'm not saying that you're wrong, I'm just wondering what causes this substantial increase in consumption... Might be that this 84 stuff was actually a completely different formula? The infamous ethanol rubbish? Which caused massive motronic confusion?!?

:lurk

[cruisin]

This is strange. Low octane gas actually contains LESS stuff that DOESN'T burn, so hypothetically you should get more energy out per gallon. (Note the word hypothetically...) I'm not saying that you're wrong, I'm just wondering what causes this substantial increase in consumption... Might be that this 84 stuff was actually a completely different formula? The infamous ethanol rubbish? Which caused massive motronic confusion?!?

:lurk

hmm, and I thought it was the other way around;

92 octane = 92% pure octane with 8% impurities/other ingredients
88 octane = 88% pure octane with 12% impurities/other ingredients
84 octane = 84% pure octane with 16% impurities/other ingredients and so on.

Plus the lower grade fuel causes inefficiencies in engine performance which may be a bigger factor than the impurities being burned.

Any petroleum chemists out there shed some light on this? :dunno I will try to remember to ask the chemist across the hall from my office tomorrow, if he's not off skiing somewhere, it's that time of year you know.

[jacco]

I will try to remember to ask the chemist across the hall from my office tomorrow, if he's not off skiing somewhere, it's that time of year you know.

Please do, I'm curious now. I don't know much about ethanol-based fuel. (I'm not claiming that I know anything about any fuel for that matter :) ). All I know is that you need higher octane number fuel in higher compression engines to avoid premature detonation of the mixture due to compression (a la diesel). So you add stuff to make sure it doesn't do that. So I'm curious to hear what the chemist has to say... Otherwise I'll spend some time on google...

Cheers,
jacco

[PGlaves]

My R1150R gets sufficiently poorer mileage on regular to make mid-grade or higher worthwhile.

It is not about the specific energy in the fuel. It is about the completion of the combustion at the right time, with the piston in the right place. In extreme cases you can hear the pinging - which is akin to hitting the piston with a ball peen hammer. In less extreme cases it is the combustion occuring a little too early and fighting the piston a little, too early on the upstroke.

[wuli959]

If your not filling your tank with a "dedicated" high octane filler line, you're probably putting more low octane gas (left in the delivery system) in then you think . . . :deal

[R4RandR]

I've also heard that lower octane gas=more efficient burn=better mileage. The higher octane gas only allows an engine to be tuned to make more power, not necessarily make more power because of using high octane fuel. Basically, the higher the octane, the harder it is to burn or pre-ignite and burns slower.

[PGlaves]

I agree - but ...

If your engine does not need higher octane you will most likely get better mileage with regular octane fuel. But, if it needs higher octane you will probably get better mileage with the correct higher octane because the fuel is burning properly at the correct time.

[jacco]

I agree - but ...

If your engine does not need higher octane you will most likely get better mileage with regular octane fuel. But, if it needs higher octane you will probably get better mileage with the correct higher octane because the fuel is burning properly at the correct time.

Makes lotza sense.
Good weekend to all! We're getting snow... :(

[robdogg]

I've read that the GSA has the ability of running on low octane regular gas (some type of switch or sensor?), but the owner's manual doesn't mention it. Maybe this feature came out after my '02 was built. Any knowledge of this? I want to run on the lowest octane I can without causing pinging under load.

Paul
'02 GSA

I'm fairly new to the BMW world; but I've not heard of a factory installed feature for this. The KTM 950 does have this feature (and I think late model 640 Adventures) - if I recall, you disconnect a wire that goes to the CDI which retards the ignition slightly (something like that anyway; it's covered in the manual)

[cruisin]

I got to talk to one of our chemists today who was working for Phillips petroleum just a couple of years ago in QC. Here is my layman's version of a very complicated explanation (the chemist says this is a very simple way to see it). The octane rating is very closely related to the amount of pure iso-octane in the formulation and the rest is not really impurities but just part of the formulation. The simplest way to grasp the concept for me was the explanation that jet fuels are very nearly 100% iso-octane while automobile fuels have a formulation that makes them have a lower percentage of iso-octane. The rating (88 or 90 or 92) comes from a comparison of caloric yield from each formulation.

100% iso-octane produces X calories per ounce when burned
92 octane fuel would then produce 92% of X calories when burned
88 octane fuel would then produce 88% of X calories when burned and so on.

Hence engines designed for higher octane fuels (higher compression engines) will run more efficiently on higher octane fuels and get better mileage than on lower octane fuels (if that octane rating is below the recommended rating for that engine). Running lower octane fuels may not cause a great deal of damage to a high compression engine but will cause it to not operate at peak efficiency and result in a decrease in fuel mileage. It could also result in some slight amount of carbon build up on valves beacuse of pre-ignition occurring as a result of the fuel being formulated for a lower compression engine.

On the other hand, running high octane fuels in a low compression engine will not increase fuel mileage because the engine is not designed to take advantage of the higher output of the fuel. And it could very well cause some damge to the engine in the way of running hot and/or slight increases in internal pressures which could damage head gaskets.

I believe most of the BMW motorcycle engines have higher octane fuels recommended due to their compression ratios. So, for me running the recommended fuel has been and will continue to be the only choice unless there is no other choice; like in Roy, NM. I am pretty anal about checking fuel mileage as a means of monitoring for problems that may be occurring in the engines. Everytime I have had no choice about using lower octane fuels, my mileage has dropped significantly on both the RT and the C.

EDIT; I went out and did a Google search on this and came up with a lot of different explanations. Some agree with what I was told at work, some don't. There is a wealth of information out there on the Internet, although I'm not sure I am capable of understanding it all, in fact, I know I'm not. Here are a few of the comments I copied and pasted here from the search. Looks like some of my understanding of Friday's explanation was spot-on and some not so much. That is assuming all of these excerpts are correct. :dunno I will continue to use the fuel grade that has proven itself to me with real mileage numbers that I have calculated for myself. I suppose everyone will probably do the same--what they think is best for them. :wave

Marshall Brain;

http://chemistry.about.com/gi/dynamic/offsite.htm?site=http://www.howstuffworks.com/question90.htm

It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.

Unknown;

http://chemistry.about.com/cs/howthingswork/a/aa070401a_2.htm

Straight-run gasoline has an octane number of about 70. In other words, straight-run gasoline has the same knocking properties as a mixture of 70% isooctane and 30% heptane. Cracking, isomerization, and other processes can be used to increase the octane rating of gasoline to about 90. Anti-knock agents may be added to further increase the octane rating. Tetraethyl lead, Pb(C2H5)4, was one such agent, which was added to gas at the rate of up to 2.4 grams per gallon of gasoline. The switch to unleaded gasoline has required the addition of more expensive compounds, such as aromatics and highly branched alkanes, to maintain high octane numbers.

Cecil Adams

http://www.straightdope.com/columns/041008.html

Dear Cecil:

In this time of high gasoline prices, the Teeming Millions need your guidance (well, at least I do). What is the difference between premium and regular gas, and is this difference worth the extra money? I normally put premium gas into my car because I don't mind paying two or three extra dollars at the pump. Am I being scammed by the gas stations, or is the benefit to my car worth it? --Jeff, via e-mail

Cecil replies:

Not to introduce a radical concept, Jeff, but have you tried reading your owner's manual? If it says to use premium, my advice is to use premium. If it says regular, use regular. The fact that your note indicates no acquaintance with such matters suggests that you may in fact be a scam victim, assuming by this you mean "someone who believes what he hears in commercials." I have a hard time working up much outrage over this deception, since discovering the facts requires so little effort. If you don't mind paying the extra money for no reason, don't expect the oil companies to suffer any pangs accepting it.

In most of the U.S., regular gas has an octane rating of 87, midgrade gas is 89, and premium is 91 or 92. (Octane ratings are lower in the mountain west due to the effects of thin air on internal combustion.) Contrary to widespread belief, the octane rating doesn't indicate how much power the fuel delivers; all grades of gasoline contain roughly the same amount of heat energy. Rather, a higher octane rating means the fuel is less likely to cause your engine to knock or ping. Knock, also known as detonation, occurs when part of the fuel-air mixture in one or more of your car's cylinders ignites spontaneously due to compression, independent of the combustion initiated by the spark plug. (The ideal gas law tells us that a gas heats up when compressed.) Instead of a controlled burn, you get what amounts to an explosion--not a good thing for your engine. To avoid this, high-octane gas is formulated to burn slower than regular, making it less likely to ignite without benefit of spark.

The majority of cars are designed to run on regular gas, and that's what the manuals tell the owners to use. Higher-performance cars often require midgrade or premium gas because their engines are designed for higher compression (higher compression = more power), and regular gas may cause knock. If your car needs high-octane gas, the manual will say so.
Using high-octane gas in a car designed for regular accomplishes little except more rapid combustion of your money. Some refuse to believe this, claiming, for example, that premium gives the family Toyota better mileage or more power. These people are in dreamland. Others say premium is purer or contains detergents that will cleanse your engine of uncouth deposits. Likewise misguided thinking--government regulations require detergents in all grades of gasoline. (BP Amoco, I notice, asserts that its premium gasoline contains more detergents than legally required; if you think that's worth 20 extra cents a gallon, be my guest.) Some automotive types claim that using premium in a car designed for regular will make the engine dirtier--something about deposits on the back side of the intake valves. I've also heard that slower-burning high-octane gas produces less power when used in ordinary cars. Believe what you like; the point is, don't assume "premium" means "better."

Occasionally you get some genius who takes the opposite tack--he spends an extra 10 or 20 grand buying a high-performance car, then decides he's going to save three bucks per tankful using regular instead of premium as specified. He figures as long as the engine doesn't knock he's OK. Wrong, carbon monoxide brain. Car engines nowadays contain knock sensors that detect detonation and automatically retard the spark to compensate. The delay means maximum gas expansion occurs when the piston is farther along in its downstroke and thus there's more room in the cylinder head. This reduces peak cylinder pressure, eliminating knock but also giving you less power and poorer mileage.

You may ask: Don't knock sensors make it hard to tell when an old car needs higher-octane gas? Years ago, when your beater started pinging on grades or under acceleration, that was the sign that carbon had built up in the cylinders, increasing compression, and it was time to switch to high-test. Now the knock sensors compensate, which seemingly might conceal the problem. Don't fret--today's fuel injection systems precisely meter the fuel-air mix, resulting in fewer unburned hydrocarbons and less carbon buildup. If you're still concerned, I'd say it makes more sense to spend $6 on a bottle of carbon clean-out juice than an extra $150 a year on high-priced gas.

--CECIL ADAMS