I run 93 in mine, that is the highest octane I can get at pumps in my part of the country.

 

 

View attachment 176616

I know.. I'm sorry I'm really wanting to understand why it's safe, or why it isn't to run 87..

 

I'm no engineer. I don't know how it detects knock. I know guys who run the Bren Tune run higher octane per the instructions.

 

There were no knock sensors prior to EU5 implementation in 2022.

My 2018 works fine on 87 octane. My 2011 absolutely had to have 89 octane.

 

Without the ability to detect knock, I guess they could use a timing curve that avoids danger at high rpm/load conditions, but you'd be leaving a good deal of power on the table..

 

The '22+ models have knock sensors and can run on regular or premium.

 

I try to run 91 octane if possible. For whatever its worth, my dealer said if I could only get 87 octane, and if I was concerned, to run in rain mode, but he didn't say I absolutely needed to do that either.

 

As you know your bike has a recommendation to use 89 AKI gasoline. A higher grade is a waste of money. In higher elevations, such as the Rocky Mountains 88 is OK. Trying to save pennies by running 87 isn't worth it to me but then what do I know.

I get a kick out of folks who will try and save a few cents on 7 gallons of gas and then go into the convenience store and buy a bottle of water priced at $16 a gallon when they can go to the soda dispenser and fill an empty bottle for free, with ice.

 

My bike will pre-det on anything lower than 91.

 

Made me laugh; reminds me of the time visiting my parents in assisted living when at the table 2 women in their 90's were loudly having a health discussion. One said to the other "my doctor says I'm pre-diabetic." My mother said "having something to worry about makes you forget you're pre-dead".

Tom

 

I like ethanol free fuel. I use pure-gas.org to seek it out when on the road. Bike really purrs on the stuff; my wallet....not so much.

 

I also run non-oxygenated fuel unless I am in a pickle. Around these parts that is typically at 91 octane. If I need to take on some oxygenated stuff I won't put in more than needed to get back to civilization.

 

I always run 91. It’s cheaper than dealing with the results of detonation.

 

Absolutely true 👍

 

Hey,
I've searched through the forums and haven't seen a real consensus on the topic. I think they recommend 89 octane in all years? I'm soon to have a 2014.
Does there seem to be any correlation between piston crack/land issues and fuel used?

My understanding of the minimum octane that can/should be used in a motor relates to the compression ratio used. This bike has a 12.2:1 compression ratio which in a normal situation, that kind of compression rate, if you wanted to get maximum power out of it you'd have to maximize timing advance, in doing so, you'd need a high octane fuel. Under high load, you'd need race fuel with 100+ Octane. Modern cars use high compression ratio's and run on regular gas. The way they get away with that is by using knock sensors. When the knock sensors detect ping, it retards the timing until it stops. When the timing is retarded, power drops, hence why some cars recommend a higher octane, not to stay safe (the computer will take care of that with timing), but to keep power output where it's supposed to be.

So that brings me to this bike. It sounds as if they don't use knock sensors. If that's the case, there has to be some other capability to detect knock, and retard timing to accommodate (at the cost of power output). Otherwise the engine is designed to run on 100+ octane fuel with a compression rate that high.

Thoughts? Is there another method that these motors detect knock?

Here's a chart that shows the relationship of compression to octane (from here) Compression Ratio Fuel Octane Chart: (All You Need To Know)

View attachment 176615

Stick with the fuel grade shown in your manual for your model year. It ain’t rocket science. And please don’t open another oil thread……

 

Ohh.. it's coming.. just kidding!

 

Compression ratio has relatively little to do with fuel AKI required. Compression (not compression ratio), which is expressed in PSI (or kPa or MPa, if you prefer French units), is a primary driver of fuel AKI requirement, along with other factors. Compression is a function of compression ratio, but also of valve timing, throttle plate position, air temp, engine coolant temp... lots of things. The chart you dug up is ludicrous, unfortunately.

 

You're right about all those things.. it just baffling to me that a high compression performance engine doesn't have destructive pre ignition running 87 octane with no knock sensor. I agree that you can tune around it with static maps. But you're leaving tons of power on the table doing so. I was hoping I'd hear that there's some sort of novel solution to sensing knock without a knock sensor.

 

I can understand the Bren tune folks who want to improve throttle response on some models, but really, how much more power do we need out of these machines? In stock form they shred tires with the best and popping wheelies is pretty hard on an already suspect front shock. The more/high performance crowd will have much to say about this, but my observation is the home run has been hit out of the park as is. There are plenty of lighter bikes with better suspension that do more with far less.

 

I can understand the Bren tune folks who want to improve throttle response on some models, but really, how much more power do we need out of these machines? In stock form they shred tires with the best and popping wheelies is pretty hard on an already suspect front shock. The more/high performance crowd will have much to say about this, but my observation is the home run has been hit out of the park as is. There are plenty of lighter bikes with better suspension that do more with far less.

You lost me after your first sentence. "Need" has nothing to do with wanting to improve performance...

Duane

 

I echo @Gunnert, what/how much do any of us really NEED? Desire drives many decisions.

 

I've brought up Ion sensing detection before. Have yet to hear from anyone with actual knowledge one way or the other but there is no way to tell just looking, you'd need access to the ECM setup. I've run 85 octane in my bike many times in rural CO and have never had any audible detonation.

 

My thinking:

If the old bikes have any kind of knock sensors BMW would not have announced knock sensors going into the 2022 to achieve EU5 compliance.

If there were knock sensors my old 2011 would not have had detonation when I was forced to use 87 octane.

 

Well, I ain't not sayin' it.

 

I've just always run 91, unless I'm in a part of the country that has 93.

 

@atc250r , dang, I didn't get that memo. I always used 89 octane in my '12 GT. Guess I was lucky I didn't burn a piston; good thing I only had 102,000 miles on that bike...

Seriously, where do/did you come up with that one? Just an FYI, detonation does cause piston failure. In the form of a burnt piston. Usually with a hole burnt through. The issue with the early K motors wasn't detonation/burnt pistons, it was cracked ring lands. There was/is speculation on what caused the cracked piston ring lands but no specific issue was ever identified nor was what changes the "Green N" made to the fueling table; again, pure speculation.

Duane

 

@atc250r , dang, I didn't get that memo. I always used 89 octane in my '12 GT. Guess I was lucky I didn't burn a piston; good thing I only had 102,000 miles on that bike...

Seriously, where do/did you come up with that one?

Duan e

102,000 miles on the original engine?

You think I’m making up a story that 2011-2012’s suffered cracked pistons, and that BMW came out with a software update to combat it? If so, I don’t know what to tell you

And cracked ring lands are most certainly a possible result of detonation. I can’t believe you’re saying a burnt hole in the piston is the only indication/result of detonation!

 

Premium fuel is $0.80 to $1.00 more than regular. Your tank holds 6 gallons. You do the math.

What everyone forgets is that premium fuel brings with it premium levels of additive. This is what keeps your intake valves clean. This is what reduces combustion chamber and piston top deposits. This is what you want.

Octane matters. Additive treat rate matters. You get both with premium fuel. Stop focusing on octane. Buy one less cup of Starbucks and put those dollars in your $30K BMW motorcycle.

I cannot share the treat rates of fuel additives between bargain convenience store and global oil company premium fuels. We synthesize the components, formulate the additives, manufacture and supply them. I can tell you the treat rate difference is both meaningful and significant. Buy global oil company premium fuels.

(My profession is testing fuel additive performance as engineering lead for the fuels group. I also formulated axle and transmission lubricants before this role.)

 

@atc250r , I give up, you win.

Duane

 

Dammit. I wanted that W.

 

At the risk of joining a needless battle, allow me to state with certainty that
1. Pistons can break ring lands with pre ignition
2. Pistons can crack at wrist pin holes with pre ignition
3. Pre ignition is a major warranty expense for automobile manufacturers, requiring a significant engine oil additive reformulation across the industry

I have a work test vehicle that experienced this, requiring a new engine. Pictures are eye opening.

Avoid pre ignition in your vehicles.

 

@Victor 60 Nobody is disputing the damage to a piston that can be caused by detonation...

Duane

 

@Victor 60, and with an engine with a questionable durability history, I choose to run 91 to reduce the likelihood of detonation. I believe it can save money and headaches in the long run. In some ICE engines would that be a waste of money? Certainly. But in the K1600, I feel it’s money well spent. Especially in the earlier models.