Nice 91 octane Ride

[BLACK WIDOW]

This AM the weather here in Oklahoma was very nice and cool (about 75 degrees) so I decided to fuel up the Spyder and go for a ride. When I filled up I decided to try the 91 octane (for the first time) and I can honestly tell you the Spyder has never ran better; pulls harder in every gear, runs very smooth with not even a slight cough or sputter, no matter how I drove it. Now I don't know if it was the cool weather or the 91 octane or a combination of both. But I will find out.nojoke:thumbup:


Michael:doorag:

 

[jvicker]

Runs better and a little better gas milage:thumbup:

 

[glynnk]

This AM the weather here in Oklahoma was very nice and cool (about 75 degrees) so I decided to fuel up the Spyder and go for a ride. When I filled up I decided to try the 91 octane (for the first time) and I can honestly tell you the Spyder has never ran better; pulls harder in every gear, runs very smooth with not even a slight cough or sputter, no matter how I drove it. Now I don't know if it was the cool weather or the 91 octane or a combination of both. But I will find out.nojoke:thumbup:


Michael:doorag:

Filled mine with premium grade this morning for a 100 mile ride. Stll surges and hesitates at most speeds, not anything major, but it wasn't doing that at all before the update recall fix.

Glynnk

 

[ptoemmes]

Does the Spyder have knock sensors?

You know where I could be going with this...

Pete

 

[BLACK WIDOW]

91 octane

Does the Spyder have knock sensors?

You know where I could be going with this...

Pete

Yes, and I think you may be going in the right direction.:thumbup:


Michael:doorag:

 

[barb36jack31]

Took my Spyder out for a 100 mi. run. Ran just great until after lunch and the temp reached 95 degrees. The surging started and did not go away until later in the day when the temp dropped below 90 or so. I'm thinking perhaps the higher temps pushed the fuel/02 ratio over into the too lean range. IMHO

 

[BLACK WIDOW]

Runs very well

I waited today until the temp was about 90 degrees so I could eliminate the cool morning temperatures being the reason for the Spyders better performance, and not the 91 octane fuel I'm running. Now I have absolutely no doubt in my simple mind that the 91 octane performs much better in my Spyder than 87 octane. The owners manual states 87 octane or higher--The or higher is what I'm going to run. I think, if the ECU has detonation sensors and can adjust the engine timing to eliminate knocking, then it must retard the timing a significant amount to allow a engine with 10.8:1 compression ratio to run on 87 octane fuel; and there goes your performance.IMHOnojoke:lecturef_smilie:

Michael:doorag:

 

[3wheeldemon]

... I think, if the ECU has detonation sensors and can adjust the engine timing to eliminate knocking, then it must retard the timing a significant amount to allow a engine with 10.8:1 compression ratio to run on 87 octane fuel; and there goes your performance.IMHOnojoke:lecturef_smilie:

Michael:doorag:

That makes a lot of sense. Most 87 octane engines run in the 9-10.5 to one compression ratios. The Aprilia version of our Rotax runs on Premium at 11.8:1. Midgrade may be the solution IMHO2.

3WD

 

[BajaRon]

I have convinced myself that Premium works better in my Spyder. I changed grades of fuel on my 5500 mile ride to and from California.

I'd run 1 grade for 5 or 6 tanks and then switch. I kept track of mileage. Regular and Mid Grade gave me about the same mileage. I may have gotten 1 mpg better with Mid Grade but under these conditions I'd say that isn't enough to say for sure.

But I consistantly got 2 to 3 MPG better with Premium (after the 1st tank) and I think the Spyder runs better (though this could be a plecebo effect).

For the few extra bucks it seems worth the additional cost.

 

[Recluze]

I have not noticed that an octane change gives me any better performance but then I am not usually running that hard any way.

But a cooler temperature will make it run better under all conditions. The little surging I have in the 4k rpm range will go away.

Technically the 91 octane should make a difference but I have never noticed it.

 

[Firefly]

That makes a lot of sense. Most 87 octane engines run in the 9-10.5 to one compression ratios. The Aprilia version of our Rotax runs on Premium at 11.8:1. Midgrade may be the solution IMHO2.

3WD

Actually it's only the 'racing' versions of their bikes that require the higher octane. The standard factory bikes with the Rotax 990V running at 11.8:1 only call for regular unleaded.

At least that's what their website says.

Also remember that octane deteriorates with time - and higher octane gas sits around longer because it doesn't sell as well as regular--- so it could be much lower in octane that what they advertise.

Mid-grade is the real ripoff as they mix it at the pump---- and you have no way of knowing at what ratio.

I'll try a tank of premium sometime soon--- but last time I did it ran like crap.


Correct me if I'm wrong--- but octane actually makes the fuel harder to burn--- thus it reduces knock from detonation.

So if your vehicle has anti-knock controls it is mechanically reducing the knock--- whereas higher octane is doing the same thing - by not burning as easily.

If this is the case - they why should one method of reducing knock be better than another?

Also - can too low of octane cause 'sputter' ? I thought it was only a knocking issue?

I've also seen 4 cylinder engines on bikes listed with compression @ 13 that didn't require premium.

 

[ptoemmes]

I waited today until the temp was about 90 degrees so I could eliminate the cool morning temperatures being the reason for the Spyders better performance, and not the 91 octane fuel I'm running. Now I have absolutely no doubt in my simple mind that the 91 octane performs much better in my Spyder than 87 octane. The owners manual states 87 octane or higher--The or higher is what I'm going to run. I think, if the ECU has detonation sensors and can adjust the engine timing to eliminate knocking, then it must retard the timing a significant amount to allow a engine with 10.8:1 compression ratio to run on 87 octane fuel; and there goes your performance.IMHOnojoke:lecturef_smilie:

Michael:doorag:

We be thinking similar, but as ofthers have mentioned - perhaps yourself - this overall post recall update is very complicated.

One thing I wonder if retarding timing could contribute to higher operating temps, lower temps, or no effect?

Has anyone who has gone to above 87 seen a change in temps?

A data logger is needed...

Pete

 

[effgjamis]

You think that ethonal may have a bearing on low vs higher octane??

 

[3wheeldemon]

...Correct me if I'm wrong--- but octane actually makes the fuel harder to burn--- thus it reduces knock from detonation.

So if your vehicle has anti-knock controls it is mechanically reducing the knock--- whereas higher octane is doing the same thing - by not burning as easily.

If this is the case - they why should one method of reducing knock be better than another?

Also - can too low of octane cause 'sputter' ? I thought it was only a knocking issue?

I've also seen 4 cylinder engines on bikes listed with compression @ 13 that didn't require premium.

A bunch of good points. You know I am not a big believer in using more octanes that what you need:
http://www.spyderlovers.com/forums/showpost.php?p=131761&postcount=30

But there seems to me that many members are getting an improvement from going to midgrade or premium. I am at a loss on this one:dontknow:. I guess this is our quest for the Holy Grail.

PS: Feel better about the midgrade mixing in the gas stations. The mix is well regulated, so you are getting the octane quoted, what is a rip-off is the pricing. For example for a mix 50/50 of regular and premium you pay closer to premium price that what the blend would indicate.

3WD

 

[BLACK WIDOW]

91 octane

Actually it's only the 'racing' versions of their bikes that require the higher octane. The standard factory bikes with the Rotax 990V running at 11.8:1 only call for regular unleaded.

At least that's what their website says.

Also remember that octane deteriorates with time - and higher octane gas sits around longer because it doesn't sell as well as regular--- so it could be much lower in octane that what they advertise.

Mid-grade is the real ripoff as they mix it at the pump---- and you have no way of knowing at what ratio.

I'll try a tank of premium sometime soon--- but last time I did it ran like crap.


Correct me if I'm wrong--- but octane actually makes the fuel harder to burn--- thus it reduces knock from detonation.

So if your vehicle has anti-knock controls it is mechanically reducing the knock--- whereas higher octane is doing the same thing - by not burning as easily.

If this is the case - they why should one method of reducing knock be better than another?

Also - can too low of octane cause 'sputter' ? I thought it was only a knocking issue?

I've also seen 4 cylinder engines on bikes listed with compression @ 13 that didn't require premium.

Firefly--My understanding is that the higher the octane the slower it burns; thus eliminating pre-ignition in the higher compression engines. If the fuel ignites before the piston has completed the compression stroke, then you loose power/efficiency, and you also run the risk of burning a hole in the top of a piston with severe pinging ; created by the pre-ignition. One way to eliminate the pre-ignition in lower octane fuels is to retard the timing, but that is essentually de-tuning the engine and again you loose power and efficiency. One can equate fuel to gunpowder, in that the only difference in a "Maginum" powder and a regular powder is the speed that it burns. A maginum powder burns slower thus propelling the bullet throughout the length of the barrel instead of an instantaneous flash. The powder burns slower thus providing force over a longer period of time. In many respects (in theory) fuel is much the same.IMHOopcorn:


Michael:doorag:

 

[BajaRon]

Firefly--My understanding is that the higher the octane the slower it burns; thus eliminating pre-ignition in the higher compression engines. If the fuel ignites before the piston has completed the compression stroke, then you loose power/efficiency, and you also run the risk of burning a hole in the top of a piston with severe pinging ; created by the pre-ignition. One way to eliminate the pre-ignition in lower octane fuels is to retard the timing, but that is essentually de-tuning the engine and again you loose power and efficiency. One can equate fuel to gunpowder, in that the only difference in a "Maginum" powder and a regular powder is the speed that it burns. A maginum powder burns slower thus propelling the bullet throughout the length of the barrel instead of an instantaneous flash. The powder burns slower thus providing force over a longer period of time. In many respects (in theory) fuel is much the same.IMHOopcorn:


Michael:doorag:

Pretty accurate analogy.

Our Spyders run a compression ratio that is too high for regular. This isn't theory, this is fact.

Sure BRP says you can run regular and the Spyder does fine on regular. No one is disputing this. But how is it that both are true?

There can be only 1 answer. BRP has modified other factors which reduce performance and allow for octane lower than our compression ratio requires.

Can we get some performance back by raising Octane? This is where the debate is because only BRP knows how this game is being played.

I found this on a High Performance Engine web page.

KNOCK-SENSOR-EQUIPPED VEHICLES
Automakers began using knock sensors in the late 1970's. When knock occurs it sends a signal to the main computer, which retards the spark timing until detonation ceases. The best thing about a knock-sensor is its ability to reduce or eliminate engine damage due to detonation. It can, however, cause spark-timing retard, which reduces horsepower and fuel economy. Using a gasoline high enough in octane to satisfy the engine under all types of conditions will ensure maximum performance.

Here is a Minimum Octane vs. Compression Ratio chart. With a compression ratio of 10.8:1 and no modifications for knock our Spyder would require 100 Octane, minimum.

So, all things being equal, even premium fuel won't get us where our compression ratio requires us to be. Even with premium we still need an anti-knock system because 92/93 is not enough.

The question is, will higher octane get our ECM to give us a more advanced spark timing, thus improved efficiency, power and mileage?

BRP could tell us for sure, but we can also experiment. That is what I have done.

 

[3wheeldemon]

Pretty accurate analogy.

Our Spyders run a compression ratio that is too high for regular. This isn't theory, this is fact.

Sure BRP says you can run regular and the Spyder does fine on regular. No one is disputing this. But how is it that both are true?

There can be only 1 answer. BRP has modified other factors which reduce performance and allow for octane lower than our compression ratio requires.

Can we get some performance back by raising Octane? This is where the debate is because only BRP knows how this game is being played.

I found this on a High Performance Engine web page.

KNOCK-SENSOR-EQUIPPED VEHICLES
Automakers began using knock sensors in the late 1970's. When knock occurs it sends a signal to the main computer, which retards the spark timing until detonation ceases. The best thing about a knock-sensor is its ability to reduce or eliminate engine damage due to detonation. It can, however, cause spark-timing retard, which reduces horsepower and fuel economy. Using a gasoline high enough in octane to satisfy the engine under all types of conditions will ensure maximum performance.

Here is a Minimum Octane vs. Compression Ratio chart. With a compression ratio of 10.8:1 and no modifications for knock our Spyder would require 100 Octane, minimum.

So, all things being equal, even premium fuel won't get us where our compression ratio requires us to be. Even with premium we still need an anti-knock system because 92/93 is not enough.

The question is, will higher octane get our ECM to give us a more advanced spark timing, thus improved efficiency, power and mileage?

BRP could tell us for sure, but we can also experiment. That is what I have done.

BajaRon: very interesting!

Just a caution: there are two octane tests the "Research Octane Number" (RON) and "Motor Octane Number" (MON). The RON is normally four numbers higher that the MON of the same gasoline sample. In the US we average them and use (RON+MON)/2 as "octane". In most other countries only RON is used. I don't know the source of your chart but I if were based in RON you would need to sustract two to the octane scale to think "American". It would still make your point but a little bit less dramatically.

3WD

 

[QuadManiac]

Our Spyders run a compression ratio that is too high for regular. This isn't theory, this is fact.

Although correct to some degree, this is not accurate for all cases... many advances have been made in combustion chamber physics since these 'absolute' numbers were formulated... for instance, combustion chamber geometry can be optimized to reduce pre-ignition and, therefore, octane requirements. Also, complex piston designs can also be incorporated, e.g., 'squish pistons', which also reduce pre-ignition and octane requirement through dynamic control of the combustible volume. (1)

However, if enough empirical evidence shows that performance does indeed increase in the :spyder2: through the use of higher octane fuels (and the many other variables, i.e., ambient temperature, humidity, elevation, etc., are held more or less constant) then ignition retardation from knock sensor detection due to too low an octane could certainly be a good explanation for the reduced performance at lower octane level.

Anybody know what the chamber geometry and piston surface are like - common, or complex?

Reference:
(1) The Internal-combustion Engine in Theory and Practice Vol 2: Combustion, fuels, materials, design; Charles Fayette Taylor, MIT Press 0-262-70027-1

 

[Firefly]

I agree--- you can no longer just look at the compression numbers and say since it's 'high' compression - it must need higher octane. Compared to the Aprilia rotax engines--- we aren't really 'high'... it's all relative.

One big misconception is that higher octane has more power - it doesn't. A gallon of 87 and a gallon of 92 have the exact same amount of energy.

The higher MPG with premium is a myth--- the only way I could see this being true would be if your engine is running poorly (knocking) with the lower octane gas. I don't believe anyone is complaining about knocking out here- and I have not heard that too low of an octane would cause sputtering.

I think that the older 70's style knock sensing systems probably didn't work anywhere near as good as what we have today. Whether it's a mechanical retardation or slower burning high octane fuel--- seems to me they are both doing the same thing.

Would be nice for someone who really knows this stuff to chime in and tell us the facts vs. our assumptions.

Unless your bike is running bad-- seat of the pants feeling of running better can be questionable. Ditto on MPG - without a lab doing it - our calculations just won't be as accurate - unless you're running the tank bone dry during the testing.

I'll try another tank soon - but last time it was ugly.....

 

[BLACK WIDOW]

91 octane

I agree--- you can no longer just look at the compression numbers and say since it's 'high' compression - it must need higher octane. Compared to the Aprilia rotax engines--- we aren't really 'high'... it's all relative.

One big misconception is that higher octane has more power - it doesn't. A gallon of 87 and a gallon of 92 have the exact same amount of energy.

The higher MPG with premium is a myth--- the only way I could see this being true would be if your engine is running poorly (knocking) with the lower octane gas. I don't believe anyone is complaining about knocking out here- and I have not heard that too low of an octane would cause sputtering.

I think that the older 70's style knock sensing systems probably didn't work anywhere near as good as what we have today. Whether it's a mechanical retardation or slower burning high octane fuel--- seems to me they are both doing the same thing.

Would be nice for someone who really knows this stuff to chime in and tell us the facts vs. our assumptions.

Unless your bike is running bad-- seat of the pants feeling of running better can be questionable. Ditto on MPG - without a lab doing it - our calculations just won't be as accurate - unless you're running the tank bone dry during the testing.

I'll try another tank soon - but last time it was ugly.....

I don't see any way that 91 octane could possibly make the Spyder run worse; 86 octane or Higher is recommended. The worst it could do is cost a little more at fill-up. I have no doubt that the 91 octane makes my ride perform better and for the small difference in price, I,ll use it. I am generally a skeptic and that is the reason I put 5000 miles on the spyder with nothing but 86 octane fuel, but now I know there is a difference, and it also makes technical sense. I don't know or really care about the fuel mileage, but better performance generally equates to more efficiency.:thumbup:
IMHO
Michael:doorag: