Gas Octane

[Spydyr]

Now now - let's not get personal here and start attacking.

Everyone is welcome to their opinion. Some opinions are based on facts, and some on fiction - but they are each persons opinion.

Rather than waste time attacking out here, if you really want to learn about octane - take 30 minutes and do some reading out here on the net.

You will find that you are correct when you say "I wouldn't add it to a vehicle that I didn't think would benefit from it either...."

Some vehicles certainly can benefit from running premium, the Spyder just isn't one of them - according to the people that designed it.

There is plenty of scientific data available on the internet that proves higher octane can not improve power or MPG unless used in an engine that specifically requires it. The Spyder doesn't (pg 22 of owners manual).

Those engines that do require it don't get more power or mpg from the fuel or the higher octane - they simply require the higher octane in order to run smoothly without knocking.

Other engines may have anti-knock systems in place to keep them running smoothly. It's simply two different solutions to the same problem in order to keep the engine running smooth. High compression engines, turbo and super charged engines may very well require the higher octane to solve the knocking problem. The Spyder engine doesn't fall into those catagories.

The error in this whole arguement is that many incorrectly think that higher octane gas has more useable power in it - it doesn't. Basic physics will tell you that you cannot get more power from something than it contains, and 87 and 91 octane gasses have identical amounts of power in them.

If you have firm scientific data (dyno and mpg readings taken in a controlled environment with calibrated equipment) that shows the Spyder to get better MPG or have more power when running premium gas, I'm sure the engineers at BRP would appreciate you sharing this data.

Seat of the pants dyno or gas-pump mpg readings without consistent riding done in a controlled environment are just not accurate enough to be taken as proof.

In the factory service manual BRP doesn't recommend 87 octane, they recommend, " a MINIMUM of 87 octane." Everyone is going to interperet it differently but I take that to mean this is the very minimum you should try to get by with, not the best thing you can use! I also believe that premium and high octane are two different things and I just can't help but think that a 10.7:1 compression engine spinning at 10,000 RPM, wouln't benefit from a higher octane or a premium fuel.

 

[Spydyr]

My thoughts are that 87 octane is recommended in large part to meet emission requirements. Because it burns faster, combustion would be more complete by the end of the power stroke, compared to higher octanes, lowering hydrocarbon production. Especially at the lower rpm's and throttle positions that they are tested at. As a manufacturer, BRP couldn't recommend actions that would violate emission standards. (My 04 Hemi pickup (that required a minimum of 89 octane at 10:1 compression) had a second set of spark plugs in each cylinder that functioned only at idle to ensure a more complete burn to meet emissive req's.) Higher AFR's and lower octane ratings may be how BRP manages the regulations...

BRP doesn't recommend 87 octane, they recommend a MINIMUM of 87 octane!

 

[boogllasti]

My Nissan has had the double plug setup for years - and they fire all the time - and it runs on 87 as recommended by Nissan.

While I'll be installing my Veypor vr2 this weekend so I can test 1/4 mile, hp, etc. - I'm not going to bother trying premium gas again. I tried it and had the exact same results that Magic Man did.

To measure and noticable difference in HP or MPG it would take a consistent environment, accurate riding patterns and good measuring devices.

Does anyone know if the high-compression 135hp version of this Rotax requires premium?

 

[Spydyr]

"Again, as I've said in a previous post, if the Spyder has a knock control system, it would make corrections long before you heard any knocking. Since we have no access to the ECM as end users or even at the dealer level for this issue, I haven't learned if it does or not. Because we don't hear about knocking issues, and the fact that BRP invested a lot of effort in other advanced systems, I'm assuming that it does. If that is the case, and higher octane fuel prevents the detonation in the first place, I end up with more power, period."


Two different ways to solve the knocking problem : Anti-knock system or higher octane.

Assuming you are correct that the Spyder uses the first solution - the problem is already solved by the knock-control system. Why would you need to solve the problem again with higher octane?

Maybe you have something wrong with your Spyder if you're having such knocking issues. I would have your dealer check things out - maybe your knock-control isn't working properly?

I've not heard of a single case of engine knock on the Spyder, but there's always a first for everything. Perhaps your dealer can figure out the problem at your 6,000 checkup.

A knock sensor doesn't solve the problem, it just relieves the symptoms. It prompts the computer to retard timing which reduces knock but at the same time reduces power!

 

[Spydyr]

I think you're missing the point...

A knock-control system retards ignition timing to mitigate or eliminate knock. Retarding ignition timing (without changing other engine parameters) has the side-effect of reducing engine power output. *If* the Spyder's engine control system incorporates a knock sensor which must continually retard ignition timing to prevent knock while using the min recommended 87 octane fuel, it stands to reason reducing or eliminating the knock by increasing the fuel's octane negates the need to retard ignition timing in the first place. In this case, switching from 87 octane to 91 octane doesn't result isn't more engine power being produced, per se, but it will eliminate the artificial reduction of produced engine power imposed by the engine control system when it retards ignition timing to prevent knock.

This entire discussion is speculative until we ascertain whether the Spyder incorporates a knock sensor. That being said, it seems to me BRP would not have published a minimum octane in the Operator's Guide if the Spyder's engine control system incorporates a knock sensor. Theoretically, the knock sensor would compensate for lower octane fuels by simply further retarding the timing. Additionally, for a vehicle marketed and sold in large part based on its performance, one wonders why BRP fails to mention the potential power and economy gains available by simply using higher octane fuel -- especially considering the Spyder's lackluster fuel mileage.

Regards,

Mark

I know I maybe interpereting it wrong but I'm glad to see that you noticed MINIMUM octane rating too.

 

[AMTJIM]

I "borrowed" a set of water injectors from a Merlin engine and run 100 LL fuel that passes through a magnetic IR filter. Each cylinder exhaust port is routed through a "Y" collector check valve with half the exhaust exiting normally, while the other half runs through a carbon scrubbing hepa filter and cryogenic chamber then directly to the airbox. The rear pulley has been removed and replaced with a speed tensioning pulley with a 75 mph break-out that has a sin-wave inhibitor signal to allow for speeds in excess of 175 mph.

 

[boogllasti]

Make sure you add a mixture of high S-value phenylhydrobenzamine and 5% reminative tetryliodohexamine, other wise you may crack a girdlespring .

 

[AMTJIM]

Maybe, but you have to go through NASA training school first. I will let you borrow the stratosphere suit, but you have to bring your own diapers.

 

[SpyderMark]

My thoughts are that 87 octane is recommended in large part to meet emission requirements. Because it burns faster, combustion would be more complete by the end of the power stroke, compared to higher octanes, lowering hydrocarbon production.

I would argue this to be true for an engine without a knock sensor -- an engine incapable of modifying ignition timing to compensate for octane.

*IF* the Spyder's engine control system does not use a knock sensor, and its ignition timing is optimized for 87 octane, using a higher octane would result in an incomplete combustion event and higher hydrocarbon emissions as you noted.

If, on the other hand, the Spyder *DOES* incorporate a knock sensor, the engine control system would advance timing when switching from lower octane to higher octane fuels allowing more time for the combustion event. In this case, there shouldn't be much difference in hydrocarbon emissions.

An incomplete combustion event results in more than just increased hydrocarbon emissions including:

• Lower economy (because you exhaust unburned fuel)
• Lower power (unburned fuel exhausted wasn't used to make power)
• Higher combustion chamber deposits (I'm sure as an A&P you've cleaned your share of dirty plugs )

I'm sure there are more, but I've only had one cup of coffee so far...

Regards,

Mark

 

[Calif-spyder]

this would have been a great question to have asked Sunday during the live chat.
Mark

 

[SpyderMark]

The motorcycle systems that I'm familiar with don't have the ability to advance ignition timing to optimize for fuel or other conditions. Only the ability to retard timing (to a point) when knock is detected. A temporary offset to the main ignition tables in the ECM.....

We're talking around each other here. I'm not saying the system would advance the ignition timing beyond the optimized setting. But if the system retarded the timing on account of 87 octane fuel, and the rider subsequently introduces a higher octane fuel, the system would then "advance" the timing back to its original, optimized setting.

Here's what I should have said, "If, on the other hand, the Spyder *DOES* incorporate a knock sensor, the engine control system would advance timing when switching from lower octane to higher octane fuels allowing more time for the combustion event. In this case, there shouldn't be much difference in hydrocarbon emissions."

I only mentioned this in response to your suggestion higher octane fuels result in higher hydrocarbon emissions. I suggest that isn't necessarily the case for an ignition system optimized to burn high-octane fuel. The timing of such a system would be tuned to account for the longer burn time of high octane fuel. I would think only a system with static timing -- a system not able to retard timing -- would exhaust unburned fuel, and only if the rider were attempting to burn high-octane fuel (slower burn rate) in such a system optimized for 87 octane (higher burn rate).

Perhaps if I stated my position a little differently...

I've *never* heard of a vehicle manufacturer optimizing the engine to burn high octane fuel, then recommending a minimum octane they know will activate a knock sensor which will retard the timing and reduce engine performance. Seems kinda silly to me. :dontknow:

The vehicles I've seen that use knock sensor technology *AND* can use high-octane fuel ususally state something to the effect that 91 octane is recommended, but lower octane fuels may be used with a subsequent loss in performance. There is no such statement in the Spyder Operator's Guide.

Regards,

Mark

 

[boogllasti]

Again, very well said Mark.

I have it on good authority that unless you have radical temp or altitude concerns, the rotax in the Spyder isn't high compression enough to require the higher octane gas - and running it in most cases will actually cause performance and MPG to DROP.

What Mark has said is right on target. Sure, the manual says MINIMUM - which means the spyder can run it just fine. I'm positive if the Spyder ran better or required higher octane - the folks at BRP would have stated so in the manual.

 

[DragonSpyder]

I have ran every octane available. I switch every time I fill up hoping to feel a difference. I can't say I have noticed a difference in performance. Unless someone gets one on a dyno or to a strip to test I can't see paying the extra money from this point forward.

 

[spyryder]

Here's a little copy 'n paste from an other forum:

with regards to a dyno, if we could figure out how to mount a spyder on the dyno, we would have numbers. at this point we are basing our info on the extensive development we've done on the aprilias. i'm sure the 106 h.p. figure is a crank number which would put the rear wheel power in the low-mid 90's. our figures are a conservative estimate based on the stage one aprilias engines we've built. the same heads, cams, pistons & fueling on an aprilia rsv-r makes over 150 r.w.h.p..

also, the factory system does not have knock detection but with our modified spark curves we have no problem running 91 oct fuel with the higher compression.

Any guesses as to who wrote that?

 

[SpyderMark]

I think it's me not explaining myself well...

I'm trying to say that it IS optimized for 87 octane, but maybe 87 isn't always the optimum fuel. That's when the knock control would operate, taking timing away under high load conditions. As the condition subsides timing is returned to it's original settings.

Ahhhh, I see what you're saying. *If* that's the case, then theoretically the computer wouldn't retard timing -- or retard it as much -- if you use higher octane. But that means you would only realize the increased performance from the higher octane during those times when the knock sensor is activated -- the rest of the time you're simply wasting gas.

I really like these types of discussions because I enjoy digging into the details. The good thing is we can all learn a lot by sharing our knowledge. The bad thing is this discussion is all still speculative until we know whether the Spyder uses a knock sensor, and if the system is optimized for 87 octane fuel.

Regards,

Mark

 

[spyryder]

Ahhhh, I see what you're saying. *If* that's the case, then theoretically the computer wouldn't retard timing -- or retard it as much -- if you use higher octane. But that means you would only realize the increased performance from the higher octane during those times when the knock sensor is activated -- the rest of the time you're simply wasting gas.

I really like these types of discussions because I enjoy digging into the details. The good thing is we can all learn a lot by sharing our knowledge. The bad thing is this discussion is all still speculative until we know whether the Spyder uses a knock sensor, and if the system is optimized for 87 octane fuel.

Regards,

Mark

Read Post #65:banghead:

 

[SpyderMark]

Read Post #65:banghead:

I understand you believe the Spyder does not incorporate a knock sensor (I suspect you are right), but you must understand there are just too many "Internet experts" out there to take another poster's word on technical details. If you have a source that may be independently verified please share it with all of us.

Regards,

Mark

 

[AMTJIM]

DIE THREAD....DIIIEEEEEEE

 

[SpyderMark]

DIE THREAD....DIIIEEEEEEE

The continuing tale of the undead thread!

 

[spyryder]

I understand you believe the Spyder does not incorporate a knock sensor (I suspect you are right), but you must understand there are just too many "Internet experts" out there to take another poster's word on technical details. If you have a source that may be independently verified please share it with all of us.

Regards,

Mark

Do the initials "Ken Zeller" (Evoluzione) sound familiar? You've taken his word as fact regarding some other issues.