Fuel octane explained.

[ChevyBuickDealer]

I think one issue in this discussion is that some seem to feel that 'Minimum' and 'Optimal' are the same thing. Don't get hung up on the word 'Recommended' without considering the context. For example. A doctor may 'Recommend' that you not eat or drink more than 3 servings of a certain food type or beverage each week. When, in reality, not eating or drinking these things at all would be optimal.

Used to be vehicles gave optimum fuel octane recommendations for a particular application. However, things have changed now that everything is computer controlled. These days you will rarely see an 'Optimum' octane recommendation. Instead, manufacturer's give 'Minimum' octane requirements. But minimum means exactly that.

What the manufacturer is describing is the computers lower limit of ability to compensate for less than optimal octane values. If you run fuel at a lower octane than this 'Recommendation' you may exceed the ability of the computer to compensate. But the optimum octane value is almost always at least 1 grade, if not 2 grades above this minimum.

The computer compensates by retarding ignition timing. Which means the spark plug fires later than it would with the optimal fuel. So if you run less than optimal fuel, you may get less than optimal performance and fuel mileage. For many, this is not a problem. And that's OK with me too. It's just that accurate information is important so that everyone can make their own, well informed decision as what fuel to use.

Years ago I tested different octanes in a 6,000 mile trip to California and back. Running several tanks of one grade and then switching to another. I filled the tank to the same spot on the neck of the tank each time for accuracy. It took awhile to get the fuel to this point. But doing it this way meant a variation of only a few ounces between fill-ups. What I found was that I got at least 10% better fuel mileage with premium (92-93 octane) than I did with either regular or mid-grade. I really did not see enough difference between the lower 2 octanes to bother.

Ambient temperature seems to have something to do with this as well. Makes sense when you understand what octane does. The hotter the ambient temperature and the harder you are working the motor, the more octane makes a difference. This is why I said that you MAY get less than optimal performance and fuel mileage using less than optimum octane. Because in cooler or cold weather. Or being easy on the motor. The computer may not need to compensate for the lower octane.

Thank you for a sensible and accurate post!

The engineers of any given engine know how much cylinder compression, cylinder volume, how hot the spark is and when it is introduced for their particular engine. Therefore they tell the consumer what the minimum should be ran in the engine. Octane is only a measure of the fuel's ability to burn in a controlled manner as opposed to exploding uncontrollably under compression. Proper octane lets the combustion happen at the time it was designed to happen. Our Rotax 1330cc ACE engine (Advanced Combustion Efficiency) has a healthy 12:1 compression ratio. Higher compression ratio requires higher octane.

It is common knowledge everywhere in the motorsports world that higher octane is required for higher performance engines but higher performance is not always a given in every street driven vehicle using higher octane. It depends on the engine design and the technology of the vehicle's powertrain. Most mass produced performance powertrains in vehicle today have 2 fuel tables built into the software and computers are quick to make adjustments for the the fuel being burned. Bottom line...Just follow the Manufacturer's recommendations!

As for me I never run Octane below 91 (That is premium in my area) or any Ethanol in any offroad equipment/toys/tools or performance engine (mowers, chainsaws, weedeaters, ATV's, UTV's...) My performance engines are the CanAm Spyder, the Chevrolet Camaro, and the Yamaha YFZ. If you question why I consider the Spyder a performance vehicle then all you need to do is look at output in relation to engine size. At 1.33 liters it produces 86.47hp/liter. That's performance. That would be like your old 5.7L 350cid Chevy producing 493hp, your current gen Chevy 6.2L producing 536hp, your 5.0L Mustang producing 432hp, or your 6.4 Hemi producing 553. In reality the normally aspirated versions of these engine referenced produce less horsepower than these calculated numbers using our ACE 1330's output ratio. Why does Chevrolet, Ford ,and Dodge recommend 91 octane in their performance engines? The same reasons CanAm recommends 91 octance! But, ultimately it is each individuals choice as to what they choose to burn in their engine and luckily the manufacturers have designed them to handle both the 87 and 91 and above. They are both listed as minimum and recommended respectively.

 

[carbonation]

91 or 93 here.
Gas is gas until the tanker that delivers is filled. That's where the proprietary additives (Mobil Synergy, Amoco Invigorate, Chevron Techron) or conventional adds (Marathon with STP) are dosed, and ethanol is added.
http://www.wearethepractitioners.com/index.php/topics/art-analysis/petroleum-supply-chain/gasoline-bobs-cbob-and-rbob-and-carbob

 

[vindex1963]

For those who believe BRP and other vehicle manufacturers are in cahoots with big oil, use whatever floats your boat. Until I accumulate enough scientific information that makes me smarter than the engineers who designed the Spyder engines I'll use what they recommend. And no, when on tour and I have been unable to get anything but 87 I can't tell any difference in the way the engine runs or the mileage I get, but that's an unusual, not routine situation. If I couldn't afford the recommended fuel, I wouldn't have bought the Spyder.

You do know they engineer to the lowest denominator not always what's best for the machine, or the performance of the machine.

 

[troop]

True, but BRP wouldn't publish 87 octane for use if it was harmful to their product.

Type Premium unleaded gasoline
87 Pump Posted AKI (RON+MON)/2 Minimum octane
92 RON
91 Pump Posted AKI (RON+MON)/2
Fuel - Refer to
FUEL REQUIREMENTS
Recommended octane
95 RON
Fuel tank capacity 27 L (7.1 U.S. gal.)

 

[ARtraveler]

I am still being "naughty." Since I got my 2019 F3L, I have filled the tank both times with 87 octane, 10% ethanol blend. I paid $2.19 a gallon for that yesterday. Price is NOT a concern, but I have been using it in all three of my bikes as well as my car.

I went to 87 about three years ago. So far, so good.

I notice NO performance issues. It gets up and goes plenty fast. I have not done a mpg test yet, but will once I get a thousand on it. I am up to five hundred in three days now.

 

[BLUEKNIGHT911]

I am still being "naughty." Since I got my 2019 F3L, I have filled the tank both times with 87 octane, 10% ethanol blend. I paid $2.19 a gallon for that yesterday. Price is NOT a concern, but I have been using it in all three of my bikes as well as my car.

I went to 87 about three years ago. So far, so good.

I notice NO performance issues. It gets up and goes plenty fast. I have not done a mpg test yet, but will once I get a thousand on it. I am up to five hundred in three days now.

hyea: .... I have well over 100,000 miles on a few different Spyders and used 87 in all of them ... I'm still happy using it ..... Mike hyea:

 

[jcthorne]

Lots of folks running the 87 and getting away with it. For me, I have always run 91 or 93 depending on what is available. The very few times premium was not available and I used 87 there was a significant reduction in performance. Returning to premium the change was far slower so not noticeable but back to 87 and the drop was again noticeable. This is due to the way the knock sensors work and adjust timing. When knock is sensed the timing is reduces very quickly. With the introduction of premium fuel back to the bike, the increase in timing and performance is much more gradual. Run what you are happy with. I much prefer they way mine runs on premium so thats what I run. I started doing so because its shown as a requirement on the emissions label on the bike but stick with it due to performance differences.

 

[IdahoMtnSpyder]

I know that when I did my 5,5000 mile, East Tennessee to California round trip. I consistently got about 3 mpg better fuel mileage with 91+ than I did with either regular or premium fuel.

Your 998 experience is contrary to my 1330 experience. Remember this thread I started 2 years ago? https://www.spyderlovers.com/forums...sed-Premium-vs-Regular&highlight=poll+premium. I just took another look at my numbers. In 2016 I rode13,889 miles and used 485 gallons of premium. In 2017 I rode 11,585 miles and used 391 gallons of regular. The riding was varied and comparable between the summers, consisting of Interstate, 2 lane state highway, mountains, dessert, Great Plains, Rocky Mountains, and so on. My MPG for 2016 was 28.64 and for 2017 it was 29.61! I got ~1 mpg better with regular than with premium. Go figure!

 

[glennm]

I am still being "naughty." Since I got my 2019 F3L, I have filled the tank both times with 87 octane, 10% ethanol blend. I paid $2.19 a gallon for that yesterday. Price is NOT a concern, but I have been using it in all three of my bikes as well as my car.

I went to 87 about three years ago. So far, so good.

I notice NO performance issues. It gets up and goes plenty fast. I have not done a mpg test yet, but will once I get a thousand on it. I am up to five hundred in three days now.

Show off! :roflblack: I just paid $1.92 per litre for 98 RON. 95 RON wasn't available at around $1.82.

PS Nice you are enjoying the F3 so much.

 

[Peter Aawen]

Your 998 experience is contrary to my 1330 experience. Remember this thread I started 2 years ago? https://www.spyderlovers.com/forums...sed-Premium-vs-Regular&highlight=poll+premium. I just took another look at my numbers. In 2016 I rode13,889 miles and used 485 gallons of premium. In 2017 I rode 11,585 miles and used 391 gallons of regular. The riding was varied and comparable between the summers, consisting of Interstate, 2 lane state highway, mountains, dessert, Great Plains, Rocky Mountains, and so on. My MPG for 2016 was 28.64 and for 2017 it was 29.61! I got ~1 mpg better with regular than with premium. Go figure!

Yeah, I can understand your results, cos all that lot ^^ does for me is highlight that the parameters on the 1330's stock tune ECU are set broadly enough so that they'll manage to keep those engines running fairly well on the Regular gas minimum, even if Premium is recommended. :lecturef_smilie:

And all that just further confirms my contention that the stock 1330 ACE Triple is a lazy engine that's waaay under-tuned that could probably run as is on FFO without too much pinging; while the stock 998 V-Twin is a lighter, revvier, peppier, & all round more exciting machine to ryde that makes better use of higher octane gas if you are brave enough feed it that, altho it can sorta get by on the lower octane stuff.... And then when you get an ECU Upgrade that goes just part way towards achieving the performance figures reliably put out by the same 998 engine in other applications, while the 998 will still run on Regular, it really needs the higher octane gas to perform at it's best, but the upside is it becomes a real Blaaast to Ryde when you give it the good stuff!! hyea: :yes: :2excited: :cheers:

However, as others have said &/or implied, you can do what you like & ryde how you like; and I'm STILL gonna be happy with my 998 V-Twin running on Premium gas! :thumbup: nojoke

 

[ARtraveler]

Show off! :roflblack: I just paid $1.92 per litre for 98 RON. 95 RON wasn't available at around $1.82.

PS Nice you are enjoying the F3 so much.

We got a taste of the "per litre" pricing when we crossed Canada on our trip to Arkansas. My basic comment on that was "Holy Cow." :yikes:

 

[south GA Farm Boy]

I run 87 and add additives, every time I am on the road I get bad gas with water in it when I buy the high test gas! Very few cars and trucks run the high test gas now days, so on the road you can get some bad gas! Sometimes at home I will buy high test because I know the best gas station to get clean fuel at! Some bad experiences on the Spyder and Harley before buying high test gas on the road! I learned to be careful!

 

[troop]

" every time I am on the road I get bad gas with water in it" Yuck !!

 

[glennm]

" every time I am on the road I get bad gas with water in it" Yuck !!

:roflblack::roflblack::roflblack:

 

[UtahPete]

The skinny on octane recommendations

A recent email from RoadRunner magazine had this article about octane ratings and recommendations. I'm not an engineer, but I'm inclined to agree with the author's summation.

What’s Right For Your Bike
For many motorcyclists, the octane numbers such as 85, 87, 89, and 91 (or 93) on the gas pump might as well read “nope,” “almost there,” and “that’s the stuff.” And it’s a logical assumption that when something costs more, it must be better, right? Not necessarily. The best choice at the pump depends entirely on the specific motorcycle, riding style, and conditions. Incorrect choices can rob riders of performance, damage the engine, and waste money.

Octane is a measure of gasoline’s resistance to self-ignite during the compression stroke, before the spark plug fires. In the U.S., the octane ratings on the pumps represent an average between “Motor” octane and “Research” octane, which are two different methods of testing octane, yielding different results. The octane ratings on European pumps typically are about four to five points higher than the U.S. (for equivalent performance) because they use a different rating system.

In a gasoline engine, if the cylinder pressure is too great as the piston compresses the air-fuel mixture, the fuel will explode prematurely as the piston is still rising. This is called “detonation” and it can blow holes in pistons if allowed to continue. To put it simply, the higher the octane number, the more resistant it is to detonation.

An engine’s octane requirement changes constantly. When coasting or idling, it is very low, and while under a heavy load, the need for octane soars. Some of the factors that determine what octane an engine needs include: ignition timing curves, air-fuel mixture, combustion chamber design, compression ratio, camshaft profiles, port designs, exhaust design, air temperature, barometric pressure, engine temperature, load, and rpm. For example, I use premium during hot summer months, mid-grade when it’s warm out, and regular over the winter or when it’s cold outside for my 2008 Road King.

An engine’s compression ratio is the ratio of the cylinder’s and combustion chamber’s volume at the bottom of the piston’s stroke to its volume when the piston reaches the top. The higher the compression, the more powerful and efficient a given engine is for its size.

As compression ratios increase, the need for higher octane typically follows, but it’s not a direct linear correlation. Air-cooled engines typically run hotter cylinder head temperatures than liquid-cooled engines; therefore, they may need higher octane despite their lower compression ratios. For example, many Harley-Davidsons run around 9:1 compression ratios, but the factory recommends premium fuel. Yet the Honda CBR954RR had 11.5:1 compression and was designed to run on regular gas—thanks to cooler running and an excellent combustion chamber design. Engines with lean air-fuel mixtures also run higher combustion chamber temperatures, which raises the octane requirement. Usually a rider will hear a metallic rattling sound (commonly called pinging) coming from the engine when one places it under load if the octane is too low.

Running fuel with too low of an octane level for operating conditions can seriously damage the engine from detonation, but what if the octane level is too high? The bottom line is that riders can save a little money by using lower octane fuels IF the engine tolerates it, but it’s better to err on the side of caution if unsure, as no damage will occur if one runs more octane than needed.

 

[FrogmanDave]

Very good information Pete. Although these are things I already knew. I always run premium (91 octane) in my motorcycles and scooters due to all of them having high compression engines. And like your article says, it is better to err on the side of safe than the other way around. The extra dollars don't bother me at all.

 

[Woodenfish]

From what I read in the article the author stated to use the fuel required by the manufacturer who designed the engine. Using improper fuel is at the choice and risk of the operator. Had the article dove in on the Spyder specifically then the article would be more appropriate to our needs. I will always use premium fuel if the manufacturer has designated it for the benefit of its engines performance needs. That recommendation isn’t based upon the gasoline manufacturers potential for profit at the expense of the consumer looking to purchase their product. If the manufacturer could lower overall operating expenses with reduced maintenance intervals, increase economy or the use of standard gasoline usage they would at moments notice.

 

[slhanks004]

I've known this for years, but thanks for posting it for those who may be unfamiliar.

 

[UtahPete]

From what I read in the article the author stated to use the fuel required by the manufacturer who designed the engine. Using improper fuel is at the choice and risk of the operator. Had the article dove in on the Spyder specifically then the article would be more appropriate to our needs. I will always use premium fuel if the manufacturer has designated it for the benefit of its engines performance needs. That recommendation isn’t based upon the gasoline manufacturers potential for profit at the expense of the consumer looking to purchase their product. If the manufacturer could lower overall operating expenses with reduced maintenance intervals, increase economy or the use of standard gasoline usage they would at moments notice.

I agree, but I know there are many long-time SLs here who believe otherwise.

 

[308gunner]

Very good information...that's why I tuned the ECU (Stage II)...so the bike no longer runs lean on fuel... And...add an octane booster...boosting from 91 to 95 octane...those two things made a big difference in performance.