Gas Prices and Octane

[Hawk]

Now that gas prices are $4 or more in many places for regular, about $.50 more for high octane, does anyone have recommendations for octane for BMW R1150R? I tend to run the highest octane for around town usage but am wondering about running regular or mid level gas for highway use.

I know this topic has been discussed before, but with the rapidly rising prices thought I would ask again. Some anaylsts predict $10 gal regular within a couple of years.


Thanks!

[toolinalong]

Hmmm, been a long time since anyone raised that question methinks. Should be fun.

My 2 cents:
I used premium (89 octane I think, the highest you can get around here) for the first couple of years, then switched to mid-grade for the last 5 years or so. It seems to actually run a bit better with the mid-grade (87 octane), but I could be full of it too. Anyhow, stepping down a notch for an experiment won't hurt nothing as far as I know.

Also, most of my local riding is between 6000 and 8000 feet elevation and higher; 40% less air (and thus less oxygen) means less power from the engine, but also less wind resistance.

[NoRRmad]

My dealer told me mid-grade, and that's what I've been using. I heard the engine ping once, but I'd just filled up at a no-name gas station.

[ProductUser]

This topic was brought up several years ago. Dean-O, a valued member of this site, suggested using lower octane fuel when the ambient temps were low (I don't remember the exact temp ranges) and higher octane during the summer months, when ambient temps were high.

Dean-O used to own a BMW dealership and has been into motorcyles for most of his entire life, so I trust his suggestions.

ProductUser

[Hawk]

Regular gas just hit $2.30 per liter in Germany today.

[def38]

While I ride a GS model, here is my recommendation regarding fuel selection;

1- Buy only from stations that maintain their equipment and turn fuel over frequently.
2- Use only the recommended octane fuel for your model. Running lower than recommended octane risks detonation some of which cannot be heard and if allowed to continue can lead to top end engine damage with resulting high repair costs...not worth the risk IMO.
3- Remember, our boxers are air/oil cooled which means combustion chamber temperatures are higher than similar power liquid cooled engine designs. By design, boxer combustion chambers run hot. Heat is your enemy. Combustion chamber temperatures skyrocket when detonation occurs. This heat, if unabated, can melt pistons, cause ring failure and cook your engine oil.

[tourer]

While I ride a GS model, here is my recommendation regarding fuel selection;

1- Buy only from stations that maintain their equipment and turn fuel over frequently.
2- Use only the recommended octane fuel for your model. Running lower than recommended octane risks detonation some of which cannot be heard and if allowed to continue can lead to top end engine damage with resulting high repair costs...not worth the risk IMO.
3- Remember, our boxers are air/oil cooled which means combustion chamber temperatures are higher than similar power liquid cooled engine designs. By design, boxer combustion chambers run hot. Heat is your enemy. Combustion chamber temperatures skyrocket when detonation occurs. This heat, if unabated, can melt pistons, cause ring failure and cook your engine oil.

A very good point, trying to save $ on gas and then paying a high repair bill.
Penny wise and pound foolish, or would that be Fuelish, sorry, couldn't help myself.

[boxermania]

Topic well discussed on this forum.....I'll share my experience without getting into the technical aspects, if someone has specific questions I'll do my best to answer.

First let’s understand the following

Assumptions
The bike has to be in a reasonable state of tune. In our bikes the TB sync is one of the major out of tune contributors....
Operator doesn't lug the engine

Facts
One gallon of gasoline has a specific caloric value (BTU's) and it is the same irregardless of grade, what changes is the additive package
Gasoline formulation varies according to region
Ethanol decreases the caloric value of gasoline, hence less power and less MPG
All engines of the same family are not the same as they are mass produced. This is included as a clarification and is especially applicable to the recurring issue with surging of the oilhead modules. In the case of my bike, if there was any surging. it was never detected.

I have always been the proponent of using the lowest gasoline grade that the engine can be operated with, see above. In my last two bikes, a 02 BMW R1150R and a 98 Suzuki Bandit 1200S, both modified for additional output I used regular, 87 grade gas with no problems whatsoever.

So that being said, it is upon the operator to evaluate what they have and how they operate the vehicle and decide on the fuel grade to use.

One last tidbit of information that could save you some $$$$, if you find that regular grade won't work, try running a tank of half regular and half mid grade and see how that works for you.

[def38]

Topic well discussed on this forum.....I'll share my experience without getting into the technical aspects, if someone has specific questions I'll do my best to answer.

First let’s understand the following

Assumptions
The bike has to be in a reasonable state of tune. In our bikes the TB sync is one of the major out of tune contributors....
Operator doesn't lug the engine

Facts
One gallon of gasoline has a specific caloric value (BTU's) and it is the same irregardless of grade, what changes is the additive package
Gasoline formulation varies according to region
Ethanol decreases the caloric value of gasoline, hence less power and less MPG
All engines of the same family are not the same as they are mass produced. This is included as a clarification and is especially applicable to the recurring issue with surging of the oilhead modules. In the case of my bike, if there was any surging. it was never detected.

I have always been the proponent of using the lowest gasoline grade that the engine can be operated with, see above. In my last two bikes, a 02 BMW R1150R and a 98 Suzuki Bandit 1200S, both modified for additional output I used regular, 87 grade gas with no problems whatsoever.

So that being said, it is upon the operator to evaluate what they have and how they operate the vehicle and decide on the fuel grade to use.

One last tidbit of information that could save you some $$$$, if you find that regular grade won't work, try running a tank of half regular and half mid grade and see how that works for you.

Here is some interesting reading on the subject of our boxers fueling and FI adjustments...

http://www.bmwsporttouring.com/faq/surge.htm

In conversing with the late Rob Lentini, he mentioned that his boxer suffered a top end meltdown due to incipient detonation which went undetected. He had been using other than 93 octane fuel.

Ethanol can provide higher engine performance. Ethanol carries an octane rating of 113 in comparison to 87 for regular gasoline. Ethanol has long been used in race engines due to the octane rating as well as the cooler combustion temperatures. Gasoline offers about 55% higher energy yield over ethanol. The use of ethanol mixed with gasoline reduces performance due to the gasoline’s higher energy value per unit volume. The ethanol is blended with gasoline to provide increased octane values, to aid to more complete combustion (ethanol is an oxygenate) and to reduce the use of expensive crude stocks.

As the use of anti-knocks in fuels increased and environmental concerns became more pronounced, tetraethyl lead was identified as an environmental danger and MTBE was substituted. MTBE is cheap to make. Natural gas is the feedstock. Then MTBE was discovered in groundwater. MTBE is highly soluble in groundwater and hence a hazard from poorly maintained leaking gasoline station storage tanks. So, MTBE was dropped in favor of ethanol.

So, where are we today regarding octane and engine performance? As mentioned by a previous poster, there are some 160 different mandated fuel blends sold as motor fuel throughout the US. Local and regional officials mandate these fuels in an attempt to abate air pollution from automobiles. Of course, these boutique fuels, as they are called, cost you and me money inasmuch as local blending must take place in order to satisfy the fuel mandates of the local government. Think about the distribution costs for all these fuel blends! The fuel station across the street might be required to sell a different blend than his competitor who is 100 yards away! This means that the same fuel truck may not be able to service both stations…ridiculous! Finally, you, the vehicle owner doesn’t know which is the best fuel for his vehicle…so, in order to compensate and correct for different levels of oxygenate in the fuel, you must have a lambda sensor, engine computer as well as fuel injection, maps, CAT plugs and other stuff to make your vehicle fuel and emissions compliant in the location or part of the world you drive in. For these reasons as well as others, messing with blending motor fuels at the pump in order to save some money carries with it performance and engine reliability risks. Oh, and remember this, the fuel station pumps blend mid-range fuel from two underground tanks of fuel. So, if you fuel up at the local station and begin blending at the pump, you likely don’t know what you end up with in your tank due to the dead volume in the pump, hose and nozzle. So, my advice? Use the recommended fuel octane rating and lower your risk of doing some expensive damage to your boxer engine.

I caution anybody who considers changing fuel octane ratings from factory recommendations, adjusting the TPS, fitting an aftermarket exhaust system which changes exhaust back pressure or fitting aftermarket air cleaners or induction components. Our boxers run on the ragged edge of stoichometry. Reduced fuel octane can cause severe engine damage.

[maduko]

Like we need more anecdotal evidence... I run regular (87) in my 1150R for daily use. When I go on a trip or plan to flog it I'll fill up with mid grade. Plugs are clean, no signs of detonation, never heard it ping. The recommendation regarding grades for summer/winter use is valid advice. Summer fuel in most parts of the country have oxygenators added.

Even more beneficial advice: never fill up when you see the tanker truck. When the tanker is making its drop it stirs up all the crap in the tanks. That's the most common way you get water in your fuel.

[cworley5150]

I've always thought it strange that my Rockster will not run well on anything less than 93 octane. It detonates bad. I can hear it with my helmet on at speed. There is even a local station that has 92 octane as their premium and that is the worst fuel I have ever ran in my bike. It really pings with that stuff. I don't buy gas there anymore, but I will have to check and see if there is any ethanol content in their fuel. It really sucks.

I find it surprising that some people can run 87 in their bikes without pinging. I wonder if the timeing is advanced or retarded somewhat from bike to bike? I've never messed with the timing on my bike and don't plan too. I'll keep running 93 from a respectable station. The cost difference on 4 gallons of gas is not enough to worry about. It's not like I'm filling up a huge SUV or anything.

[def38]

There is even a local station that has 92 octane as their premium and that is the worst fuel I have ever ran in my bike. It really pings with that stuff. I don't buy gas there anymore, but I will have to check and see if there is any ethanol content in their fuel. It really sucks.

You will find ethanol in all grades of motor fuels throughout the US. In some areas, you will find E85 fuel used in FFV equipped vehicles. E85 is 85% ethanol, 15% gasoline. Do NOT use it in your BMW...it will not run.

The 92 octane fuel you refer to may be due to the fuel blend mandated by the local politicians...(what do they know about piston engines, fuels and emissions?)

[DSKYZD]

I'd just like to echo cworley5150's experience and opinion about using the higher octanes. I recently put regular 87 octane in my bike, it was not happy when rolling on throttle. We are in the same geographic area so we get the same blends of fuel. Premium fuel for my bike, even at $4+/gallon.

[Samiam]

Here's my two cents: Some time ago, on the Miata forum, octane was discussed ad nauseum. The gist of it was that increased octane means the fuel is more resistant to ignition, thus increasing carbon buildup if the engine does not actually need the higher octane.

I've tried 93, 91 amd 89 octane and my best mileage has been with the lowest octane (without ethanol, something increasingly hard to find in my neck of the woods). I've never heard any pinging and I reject the premise of "silent pinging" as nonsense. I hedge my bets now by filling up every other time with 89 and then 91 octane. I think the synergy of the two fuels places the octane level where I need it to be.

Paul Glaves, Boxermania and MikeCam will probably excoriate me for my actions but it works for me. I also frequently shift at 2,500 revs if I'm not in a hurry and I'm sure this makes Roadster owners as furious as my driving with the Miata's top up does the "girly car" drivers.

[def38]

Some detonation is audible, some is not. The audible detonation is more severe however, the inaudible detonation is more likely to damage your engine because you take no action to abate it. In the end, it is the severe heat caused by the detonation, audible or not, that does the damage.

Ignition timing plus anti-knock additives are your best bet to insure detonation does not occur.

[toolinalong]

Ladies and Gentlemen,

I am increasing my contribution from 2 cents to a nickel.

All this talk has made me want to do some more research. And I have decided that my previous comment, wherein I stated that stepping down a grade may be ok, may have been a bit too kneejerk of a reaction to the question, as it was based solely on my own experience up here at lofty altitudes. Now I think that other factors need to be considered.

My bike is a 2002. A few musings:

1. My manual says: Refuel only with super (premium) grade fuel to DIN 51607 standard or equivalent, minimum octane number 95 (RON) or 85 (MON), AKI 91 Premium
2. Using the U.S. octane rating method of R+M/2 translates to 95 + 85 = 180/2 = 90, which thus is the manuals minimum called for octane rating for the bike (it does not specify, so one assumes that it assumes you are at sea level).
3. Front Range Colorado (elevation 5000-9000 feet) gas is lower in octane then at sea level (see below), so our 87 octane (which is what I have been using) mid-grade works the same as the 91 octane at sea level.
4. The underlying reason for this seems to be that the higher altitude (and thus lower atmospheric pressure) effectively lowers the actual compression ratio achieved within the engine, therefore less octane is needed to avoid knocking (pinging).
5. I have put 67000 miles on her. At 42 mpg (my guess for my overall mileage) I would have burned 1,595 gallons of gas so far. At a 10 cents per gallon price differential (again the normal around here) I would have spent $159.50 over the 6 years of riding it, or $ 26.67 per year if I had been buying premium. The cost of dinner and a few beers at my favorite local pub.
6. When I road trip, I always buy mid-grade, which means in lower elevations I am buying 89 or better octane fuel.
7. In the early days of ownership when I was still learning how to properly ride the bike (and was using premium), it would sometimes ping when I was going uphill in the narrow, steep (10% grade) part of the canyon road I take every day to work (in season of course). Learning which gear I should be using in order to keep the revs up and be at the speed I wanted to be at eliminated that.
8. There is so much information on this topic all over the internet, but I liked this one for it's clarity, even though it is wikipedia: http://en.wikipedia.org/wiki/Octane_rating
9. An excerpt from that article:
In the Rocky Mountain (high altitude) states, 85 octane is the minimum octane and 91 is the maximum octane available in fuel. The reason for this is that in higher-altitude areas, a typical combustion engine draws in less air per cycle due to the reduced density of the atmosphere. This directly translates to reduced absolute compression in the cylinder, therefore deterring knock. It is safe to fill up a car with a carburetor that normally takes 87 AKI fuel at sea level with 85 AKI fuel in the mountains, but at sea level the fuel may cause damage to the engine. In some east coast states, up to 94 AKI is available [5]. In parts of the Midwest (primarily Minnesota, Illinois and Missouri) ethanol based E-85 fuel with 105 AKI is available [6].
California fuel stations will offer 87, 89, and 91 octane fuels, and at some stations, 100 or higher octane, sold as racing fuel. Until 2003 or 2004, 92 octane was offered in lieu of 91.

[def38]

Ladies and Gentlemen,

I am increasing my contribution from 2 cents to a nickel.

All this talk has made me want to do some more research. And I have decided that my previous comment, wherein I stated that stepping down a grade may be ok, may have been a bit too kneejerk of a reaction to the question, as it was based solely on my own experience up here at lofty altitudes. Now I think that other factors need to be considered.

My bike is a 2002. A few musings:

1. My manual says: Refuel only with super (premium) grade fuel to DIN 51607 standard or equivalent, minimum octane number 95 (RON) or 85 (MON), AKI 91 Premium
2. Using the U.S. octane rating method of R+M/2 translates to 95 + 85 = 180/2 = 90, which thus is the manuals minimum called for octane rating for the bike (it does not specify, so one assumes that it assumes you are at sea level).
3. Front Range Colorado (elevation 5000-9000 feet) gas is lower in octane then at sea level (see below), so our 87 octane (which is what I have been using) mid-grade works the same as the 91 octane at sea level.
4. The underlying reason for this seems to be that the higher altitude (and thus lower atmospheric pressure) effectively lowers the actual compression ratio achieved within the engine, therefore less octane is needed to avoid knocking (pinging).
5. I have put 67000 miles on her. At 42 mpg (my guess for my overall mileage) I would have burned 1,595 gallons of gas so far. At a 10 cents per gallon price differential (again the normal around here) I would have spent $159.50 over the 6 years of riding it, or $ 26.67 per year if I had been buying premium. The cost of dinner and a few beers at my favorite local pub.
6. When I road trip, I always buy mid-grade, which means in lower elevations I am buying 89 or better octane fuel.
7. In the early days of ownership when I was still learning how to properly ride the bike (and was using premium), it would sometimes ping when I was going uphill in the narrow, steep (10% grade) part of the canyon road I take every day to work (in season of course). Learning which gear I should be using in order to keep the revs up and be at the speed I wanted to be at eliminated that.
8. There is so much information on this topic all over the internet, but I liked this one for it's clarity, even though it is wikipedia: http://en.wikipedia.org/wiki/Octane_rating
9. An excerpt from that article:
In the Rocky Mountain (high altitude) states, 85 octane is the minimum octane and 91 is the maximum octane available in fuel. The reason for this is that in higher-altitude areas, a typical combustion engine draws in less air per cycle due to the reduced density of the atmosphere. This directly translates to reduced absolute compression in the cylinder, therefore deterring knock. It is safe to fill up a car with a carburetor that normally takes 87 AKI fuel at sea level with 85 AKI fuel in the mountains, but at sea level the fuel may cause damage to the engine. In some east coast states, up to 94 AKI is available [5]. In parts of the Midwest (primarily Minnesota, Illinois and Missouri) ethanol based E-85 fuel with 105 AKI is available [6].
California fuel stations will offer 87, 89, and 91 octane fuels, and at some stations, 100 or higher octane, sold as racing fuel. Until 2003 or 2004, 92 octane was offered in lieu of 91.

So, what is your point? What should we use for fuel? Which grade (octane)?

[Rigby]

I am new to this site, and new to owning a BMW boxer. I just bought a 2004 R1150r with just under 6000k on it. Since I live in the northern front range of Colorado, it is good news to here that I can use mid-grade in my bike. Thanks for all the info! Is there a difference between the single spark and dual spark bikes in terms of the fuel grade usage and/or gas mileage?

[toolinalong]

def38 asks "So, what is your point? What should we use for fuel? Which grade (octane)?"

My answer is everyone must investigate the issue as much as they feel like and then make up their own minds, like we always do; you have, so have I, and we are not exactly very far apart in our opinions. I will buy the octane rating that the manual calls for, just like I've been doing. I just did not know that I was doing it before today's research told me what the real effect of altitude is. And the cost of doing so is insignificant even at 20 cents more per gallon.

[towerworker]

Rigby--

I put 42K on a single spark 03, and currently have an 04 dual spark. I ran predominately 91 octane in the 03 and my milage averaged 50. Best I ever got was 56. I am a fairly conservative rider. I have not had the 04 very long and have only put 2500 or so on it. It now has about 20K. I have been running 89 octane recently because of higher fuel prices and got 54.1 this past weekend.

I really can't tell any real difference in the running of either bike.