Fuel octane explained.

[Don'tPanic]

Before Spyders are made electric we have to deal with gasoline. It's dirty, it smells and it's way too complicated. I never liked chemistry anyway.
I've seen too many erroenous threads and posts here to remain quiet, so here's everything you need to know about "Premium" vs "Regular" gas and which one is right for you.

Long Story Short (very simplified):

1. Modern Spyders run on Premium Gas, or for USA: octane rating of 91 (it's different in every country).
Here's from the owners manual: "Use premium unleaded gasoline with an AKI (RON+MON)/2 octane rating of 91, or an RON octane rating of 95". (See your owner's manual)
Yes, you can run your Spyder on lower octane fuels, but it comes at a cost (see #4)

2. This has nothing to do with how one grade burns hotter than another (it's the same), or how "Premium" is better than "Regular" (it's not)

3. The ONLY reason for this octane requirement is the engine compression ratio. That's it. Nothing more, nothing less. It's all about compression. Simple physics and chemistry.
Higher octane fuels resist to self-combustion due to the heat of the compression. The higher the engine compression, the higher the requirement for octane. Spyder engines have a very high compression ratio (12.2:1 for twins and 12:1 for triples) Any engine with compression over 11:1 has to have a "Premium" gas.
NOTE: I only looked up compression of modern Rotax engines. Yours might be different.

4. To those who run on "Regular" gas: your engine will knock. Here's what you need to know: "Burning fuel with a lower octane rating than that for which the engine is designed often results in a reduction of power output and efficiency. Many modern engines are equipped with a knock sensor (a small piezoelectric microphone), which sends a signal to the engine control unit, which in turn retards the ignition timing when detonation is detected. Retarding the ignition timing reduces the tendency of the fuel-air mixture to detonate, but also reduces power output and fuel efficiency."

5. "Premium", "Supreme", "Plus" and "Regular" terms are completely bogus and misleading. It's all the same gasoline. In fact, most of the gas stations use the same refineries. The difference is in additives. In simple terms: higher octane gas has more expensive additives and lower octane has cheaper additives. "Plus" grade gas is just a mixture of "Regular" and "Premium".

6. A more expensive, high octane fuel does absolutely nothing for the engine designed to run on lower octane fuels, however, a low octane fuel will damage or degrade performance and fuel economy of the engine designed to run on a high octane fuel.

If you want to know more, here's a good video: https://youtu.be/WYlk9C1o0nk
(I'm not affiliated with them in any way)

I hope this helps

 

[Mad Mac]

HIGHER OCTANE USE

I agree with your post. BUTTT I am one to use "premium" when I'm out on the road and it's a habit of mine when it comes to my recreational vehicles. Although the cost is higher, I feel I do get a little extra benefit out of it, especially in the corn states. We do pull a trailer 65% of the time when out on the road and I do notice around 2MPG gain between reg, unleaded and prem. unleaded overall, even when just 2-up riding. So for me that's the benefit I see. As for performance, not much of a "seat of the pants" difference that this old guy can feel. :doorag:

 

[BLUEKNIGHT911]

OCTANE & PERFORMANCE

Some truth can be found in most lengthy statements ...... What you haven't addressed is load or stress ..... My 1330 has been running on 87 octane almost exclusively ...... However if I was planning to ride with a heavy passenger, while pulling a 400lb trailer, in mountainous terrain I would switch to 91 octane ( for at least 500mi prior to the trip ) . Do you think the anti " knock " feature is activated right after the engine is fired ??? ..... That has not been my experience, but it's your Spyder and your money.... so do what you think is best ......... Mike :thumbup:

 

[BLUEKNIGHT911]

OCTANE

I agree with your post. BUTTT I am one to use "premium" when I'm out on the road and it's a habit of mine when it comes to my recreational vehicles. Although the cost is higher, I feel I do get a little extra benefit out of it, especially in the corn states. We do pull a trailer 65% of the time when out on the road and I do notice around 2MPG gain between reg, unleaded and prem. unleaded overall, even when just 2-up riding. So for me that's the benefit I see. As for performance, not much of a "seat of the pants" difference that this old guy can feel. :doorag:

I see you have a 1330 engine :yes:..... they avg approx. 38mpg .... 190mi. = about 5 gal of fuel ..... 2mpg gain = 10 +/- extra miles per fill ...... at an avg .50 extra cost per gal. = $2.50 .....So $2.50 is what you are spending to go another 10miles further than me .....If my math is wrong please explain ....... Mike :thumbup::thumbup:

 

[Brentc]

Thanks for the info

Thanks for the concise run down. I think you explained things pretty well in a short manner. :thumbup:

Before Spyders are made electric we have to deal with gasoline. It's dirty, it smells and it's way too complicated. I never liked chemistry anyway.
I've seen too many erroenous threads and posts here to remain quiet, so here's everything you need to know about "Premium" vs "Regular" gas and which one is right for you.

Long Story Short (very simplified):

1. Spyders run on Premium Gas, or for USA: octane rating of 91 (it's different in every country).
Here's from the owners manual: "Use premium unleaded gasoline with an AKI (RON+MON)/2 octane rating of 91, or an RON octane rating of 95".
Yes, you can run your Spyder on lower octane fuels, but it comes at a cost (see #4)

2. This has nothing to do with how one grade burns hotter than another (it's the same), or how "Premium" is better than "Regular" (it's not)

3. The only reason for this octane requirement is the engine compression ratio. That's it. Nothing more, nothing less. It's all about compression. Simple physics and chemistry.
Higher octane fuels resist to self-combustion due to the heat of the compression. The higher the engine compression, the higher the requirement for octane. Spyder engines have a very high compression ratio (12.2:1 for twins and 12:1 for triples) Any engine with compression over 11:1 has to have a "Premium" gas.

4. To those who run on "Regular" gas: your engine will knock (fuel will detonate before the spark). Here's what you need to know: "Burning fuel with a lower octane rating than that for which the engine is designed often results in a reduction of power output and efficiency. Many modern engines are equipped with a knock sensor (a small piezoelectric microphone), which sends a signal to the engine control unit, which in turn retards the ignition timing when detonation is detected. Retarding the ignition timing reduces the tendency of the fuel-air mixture to detonate, but also reduces power output and fuel efficiency."

5. "Premium", "Supreme", "Plus" and "Regular" terms are completely bogus and misleading. It's all the same gasoline. In fact, most of the gas stations use the same refineries. The difference is in additives. In simple terms: higher octane gas has more expensive additives and lower octane has cheaper additives. "Plus" grade gas is just a mixture of "Regular" and "Premium".

6. A more expensive, high octane fuel does absolutely nothing for the engine designed to run on lower octane fuels, however, a low octane fuel will damage or degrade performance and fuel economy of the engine designed to run on a high octane fuel.

I hope this helps

 

[Chupaca]

Thanks

Well put. I always use the recommended fuel and knew the difference was in the additives. In south america we had octanes fron 66 on up to 95..:yikes: don't know how it is now but we used 66 to strip wax build up from hardwood floor..:roflblack:

 

[Hypurone]

Before Spyders are made electric we have to deal with gasoline. It's dirty, it smells and it's way too complicated. I never liked chemistry anyway.
I've seen too many erroenous threads and posts here to remain quiet, so here's everything you need to know about "Premium" vs "Regular" gas and which one is right for you.

Long Story Short (very simplified):

1. Spyders run on Premium Gas, or for USA: octane rating of 91 (it's different in every country).
Here's from the owners manual: "Use premium unleaded gasoline with an AKI (RON+MON)/2 octane rating of 91, or an RON octane rating of 95".
Yes, you can run your Spyder on lower octane fuels, but it comes at a cost (see #4)

2. This has nothing to do with how one grade burns hotter than another (it's the same), or how "Premium" is better than "Regular" (it's not)

3. The only reason for this octane requirement is the engine compression ratio. That's it. Nothing more, nothing less. It's all about compression. Simple physics and chemistry.
Higher octane fuels resist to self-combustion due to the heat of the compression. The higher the engine compression, the higher the requirement for octane. Spyder engines have a very high compression ratio (12.2:1 for twins and 12:1 for triples) Any engine with compression over 11:1 has to have a "Premium" gas.

4. To those who run on "Regular" gas: your engine will knock (fuel will detonate before the spark). Here's what you need to know: "Burning fuel with a lower octane rating than that for which the engine is designed often results in a reduction of power output and efficiency. Many modern engines are equipped with a knock sensor (a small piezoelectric microphone), which sends a signal to the engine control unit, which in turn retards the ignition timing when detonation is detected. Retarding the ignition timing reduces the tendency of the fuel-air mixture to detonate, but also reduces power output and fuel efficiency."

5. "Premium", "Supreme", "Plus" and "Regular" terms are completely bogus and misleading. It's all the same gasoline. In fact, most of the gas stations use the same refineries. The difference is in additives. In simple terms: higher octane gas has more expensive additives and lower octane has cheaper additives. "Plus" grade gas is just a mixture of "Regular" and "Premium".

6. A more expensive, high octane fuel does absolutely nothing for the engine designed to run on lower octane fuels, however, a low octane fuel will damage or degrade performance and fuel economy of the engine designed to run on a high octane fuel.

I hope this helps

You are NOT completely correct with the statement in bold. If there were no provisions within the ECU fuel/timing maps to alter (advance) timing, I would agree with you for the most part. BUUUUT, since there is, the engine can take advantage of more ignition timing with premium fuels than it can with regular. Via the very same "knock sensor" you mention as it WILL cut timing with lower octane.... Therefore, there IS more built in to using premium fuel than CR....

Using an octane higher than what is required will def not gain you anything as you mention but I would use it over regular if I had to choose between them.....

 

[Bob Denman]

:agree: the dang engines will run on anything that they can get to burn; the computer makes sure of that.


But they'll just run better on the proper fuel! :thumbup:

 

[ARtraveler]

Before Spyders are made electric we have to deal with gasoline. It's dirty, it smells and it's way too complicated. I never liked chemistry anyway.
I've seen too many erroenous threads and posts here to remain quiet, so here's everything you need to know about "Premium" vs "Regular" gas and which one is right for you.

Long Story Short (very simplified):

1. Spyders run on Premium Gas, or for USA: octane rating of 91 (it's different in every country).
Here's from the owners manual: "Use premium unleaded gasoline with an AKI (RON+MON)/2 octane rating of 91, or an RON octane rating of 95".
Yes, you can run your Spyder on lower octane fuels, but it comes at a cost (see #4)

2. This has nothing to do with how one grade burns hotter than another (it's the same), or how "Premium" is better than "Regular" (it's not)

3. The only reason for this octane requirement is the engine compression ratio. That's it. Nothing more, nothing less. It's all about compression. Simple physics and chemistry.
Higher octane fuels resist to self-combustion due to the heat of the compression. The higher the engine compression, the higher the requirement for octane. Spyder engines have a very high compression ratio (12.2:1 for twins and 12:1 for triples) Any engine with compression over 11:1 has to have a "Premium" gas.

4. To those who run on "Regular" gas: your engine will knock (fuel will detonate before the spark). Here's what you need to know: "Burning fuel with a lower octane rating than that for which the engine is designed often results in a reduction of power output and efficiency. Many modern engines are equipped with a knock sensor (a small piezoelectric microphone), which sends a signal to the engine control unit, which in turn retards the ignition timing when detonation is detected. Retarding the ignition timing reduces the tendency of the fuel-air mixture to detonate, but also reduces power output and fuel efficiency."

5. "Premium", "Supreme", "Plus" and "Regular" terms are completely bogus and misleading. It's all the same gasoline. In fact, most of the gas stations use the same refineries. The difference is in additives. In simple terms: higher octane gas has more expensive additives and lower octane has cheaper additives. "Plus" grade gas is just a mixture of "Regular" and "Premium".

6. A more expensive, high octane fuel does absolutely nothing for the engine designed to run on lower octane fuels, however, a low octane fuel will damage or degrade performance and fuel economy of the engine designed to run on a high octane fuel.

I hope this helps

Good information. I am afraid you started something though. :roflblack: My "usual" comments have not changed since about two months ago.

 

[rays hell]

Octane

My thought is All gasoline deteriorates. The most purchased gas will always be the freshest gas.
91 octane is recommended but I think the Spyder will run just fine on 87. Also considering different intake air temps
and oxygen levels at higher altitudes, I don't believe 87 vs.
91 octane will make a difference in 100k miles.
I'm sticking with 87.

 

[Don'tPanic]

All good points

Thank you for your feedback. Those are all good points.
The engine management and gasoline chemistry is more complicated than can be discussed here, that's why I stressed my oversimplification.

When using 87 octane fuel you're not guaranteed that each and every stroke of the piston will produce a "knock", same with 91 octane fuel - it doesn't guarantee that there will be absolutely no "knocks" - that's why there's a knock sensor and that's why ECU (Engine Control Unit) is made to change ignition timing.

It's all about probability - there's lower probability that "Premium" gas will self-ignite in a higher compression engine under certain stress conditions.

Thanks, and Don't Panic

 

[billybovine]

You have said what I have been saying for years. But it still does not sink in.

There is one error by ommission in post 1. Not all Spyders require high octane fuel, GS/RS models from 2008 to 2012, the reccomended fuel is reguler because of the lower compression ratio in that series of engine.

 

[Mad Mac]

I see you have a 1330 engine :yes:..... they avg approx. 38mpg .... 190mi. = about 5 gal of fuel ..... 2mpg gain = 10 +/- extra miles per fill ...... at an avg .50 extra cost per gal. = $2.50 .....So $2.50 is what you are spending to go another 10miles further than me .....If my math is wrong please explain ....... Mike :thumbup::thumbup:

I avg. a little better than that. So... I just put fuel in it and turn the key and if it starts, I let the smoke from the rear tire clear from my forward view and PIN IT! And I don't worry about too much until I have to fill up again and then the whole process starts over again. We could debate this, but WHY??:joke:

 

[Fat Baxter]

My two cents: because of the EFI system, the Spyder will eat anything you put in it in a pinch.

If you're riding solo and not packing a lot of stuff, you're probably safe using regular. I figure you're not stressing the engine. It might be a different matter if you're riding two-up and/or pulling a trailer. Then a higher octane may be warranted.

Speaking of price savings, I recall the bad old days when the spread between regular, regular plus, and premium was only a nickle each way (e.g., $1.00 vs. $1.05 vs $1.10). A little while back when refueling in Georgia, the spread between regular and premium was almost a dollar. That's a six-dollar per tank difference. :shocked:

 

[rustynail51]

adding sea foam

does adding afew ounces of seafoam to the tank each fill change the octain rating

 

[Don'tPanic]

Sea Foam

does adding afew ounces of seafoam to the tank each fill change the octain rating

No. Sea Foam is a detergent and a stabilizer. It dissolves carbon deposits and controls the moisture in the gas. It does not change the octane number, but it does prevent gas deterioration.

You can avoid spending money on fuel detergents by putting Top Tier gas in your tank. Just Google "Top Tier gas"

 

[BrianO]

Before Spyders are made electric we have to deal with gasoline. It's dirty, it smells and it's way too complicated. I never liked chemistry anyway.
I've seen too many erroenous threads and posts here to remain quiet, so here's everything you need to know about "Premium" vs "Regular" gas and which one is right for you.

Long Story Short (very simplified):

1. Spyders run on Premium Gas, or for USA: octane rating of 91 (it's different in every country).
Here's from the owners manual: "Use premium unleaded gasoline with an AKI (RON+MON)/2 octane rating of 91, or an RON octane rating of 95".
Yes, you can run your Spyder on lower octane fuels, but it comes at a cost (see #4)

2. This has nothing to do with how one grade burns hotter than another (it's the same), or how "Premium" is better than "Regular" (it's not)

3. The only reason for this octane requirement is the engine compression ratio. That's it. Nothing more, nothing less. It's all about compression. Simple physics and chemistry.
Higher octane fuels resist to self-combustion due to the heat of the compression. The higher the engine compression, the higher the requirement for octane. Spyder engines have a very high compression ratio (12.2:1 for twins and 12:1 for triples) Any engine with compression over 11:1 has to have a "Premium" gas.

4. To those who run on "Regular" gas: your engine will knock (fuel will detonate before the spark). Here's what you need to know: "Burning fuel with a lower octane rating than that for which the engine is designed often results in a reduction of power output and efficiency. Many modern engines are equipped with a knock sensor (a small piezoelectric microphone), which sends a signal to the engine control unit, which in turn retards the ignition timing when detonation is detected. Retarding the ignition timing reduces the tendency of the fuel-air mixture to detonate, but also reduces power output and fuel efficiency."

5. "Premium", "Supreme", "Plus" and "Regular" terms are completely bogus and misleading. It's all the same gasoline. In fact, most of the gas stations use the same refineries. The difference is in additives. In simple terms: higher octane gas has more expensive additives and lower octane has cheaper additives. "Plus" grade gas is just a mixture of "Regular" and "Premium".

6. A more expensive, high octane fuel does absolutely nothing for the engine designed to run on lower octane fuels, however, a low octane fuel will damage or degrade performance and fuel economy of the engine designed to run on a high octane fuel.

I hope this helps

I had a neighbor who is a chemical engineer and worked for an oil refinery. He also knows lots about automobiles. The above explaination is exactly how he explained it to me.

 

[IdahoMtnSpyder]

4. To those who run on "Regular" gas: your engine will knock (fuel will detonate before the spark). Here's what you need to know: "Burning fuel with a lower octane rating than that for which the engine is designed often results in a reduction of power output and efficiency. Many modern engines are equipped with a knock sensor (a small piezoelectric microphone), which sends a signal to the engine control unit, which in turn retards the ignition timing when detonation is detected. Retarding the ignition timing reduces the tendency of the fuel-air mixture to detonate, but also reduces power output and fuel efficiency."

Correction: Fuel igniting before the spark ignites is pre-ignition. Knock is the collision of the ignition flame combustion front with the flame front from detonation. Detonation is a part of the air/fuel mixture that spontaneously combusts due to pressure. However, the pressure from compression by itself is not enough to cause detonation. What causes detonation is a part of the air/fuel mixture that is away from the spark ignited flame front is additionally compressed by the increase in cylinder pressure caused by the spark ignited A/F mix burning. Peak cylinder pressure occurs about 16° after top dead center and this is the point that detonation will occur. Detonation can, but seldom does, occur with pre-ignition. When it does the engine most assuredly will be destroyed.

Our Spyders are not suffering from pre-ignition. If they were we would be reading all kinds of posts about engines literally blowing up and pistons melting. But they very well may be suffering from post spark detonation. That's where the knock sensor comes into play. One way to prevent detonation is to retard the spark timing. This gives time for the piston to drop down a bit farther thus reducing the combustion chamber pressure at the point where detonation is likely to occur. As Don'tPanic says, the octane additive increases the pressure/temperature point at which the fuel will self combust. If our engines were detonating we'd probably be hearing it. But the knock sensor compensates for lower octane rating and prevents detonation from occurring. Also, Rotax and BRP aren't going to openly admit it, but the engines may very well be designed to tolerate some level of detonation or knock. Here's one good discussion of these issues: http://www.contactmagazine.com/Issue54/EngineBasics.html. There are many other articles out there with some variation in the definitions and warnings of damage.

As I said in my thread about mileage vs premium or regular, the only way we will really know what damage is being done, if any, by running lower than specified octane fuel is to dismantle two engines with similar high mileages, one running regular mostly, and the other running 91 octane only. As my graph of MPG shows octane rating has no to very little affect on MPG. http://www.spyderlovers.com/forums/showthread.php?109153-Guess-when-I-used-Premium-vs-Regular

 

[Little Blue]

Fuel

My 2 . USE the Fuel as per the manual. :thumbup: Happy SPYDER DAY.

 

[SteveP]

Yes but

Technical common sense won't convince people to do anything they aren't already doing . Fuel and lubricant is the first thing we covered in trade school 30 years ago and the only thing that has changed slightly is the technology to adjust ignition timing .... if premium was the same price people would stop arguing that " their bike runs just fine on regular " and likely follow their owners manual. I know with my 2003 Silverado SS it cost me $10 a tank more to run premium ( as per manual) in those 6L engines , but I figured I would take the advise of the engineering people at GM