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Gas Octane
- Thread starter Spyderjuice
- Start date
boogllasti
New member
This is very common and well known on these Rotax engines. Good idea to get that oil flowing anyway.
I have found out that since I added the fuel pressure mod (along with race airflow, o2 mod and Hindle) that if I want to I can take off dead cold without any sputter.
I increased my fuel pressure from 50 psi to 60 psi after adding the fuel mod. It made all the difference in the world! Spyder goes like a bat out of hell now! On 87 octane too!
As far as the octane debate - do some research online and you will find the information is very clear about higher octane not helping (and possibly hurting) performance *if* the engine doesn't specifically require the higher octane - which the Rotax doesn't.
I've never checked MPG on the Spyder - and don't plan to, but I have done various mods to increase power and I've got a good seat of the pants feel for what really works.
I'll be installing my Veypor VR2 this weekend so I can actually see any performance gains or losses, as well as 1/4 mile and 0-60 times.
boogllasti
New member
Good paragraph from the wiki link posted above:
Many high-performance engines are designed to operate with a high maximum compression and thus demand high-octane premium gasoline. A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. This is not true. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.
Many high-performance engines are designed to operate with a high maximum compression and thus demand high-octane premium gasoline. A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. This is not true. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.
AMTJIM
New member
What we have:
High-performance engines typically have higher compression ratios and are therefore more prone to detonation, so they require higher octane fuel
Yeah, what HDX said:
Higher octane ratings correlate to higher activation energies. Activation energy is the amount of energy necessary to start a chemical reaction. Since higher octane fuels have higher activation energies, it is less likely that a given compression will cause detonation.
It might seem odd that fuels with higher octane ratings explode less easily and can therefore be used in more powerful engines. However, an explosion is not desired in an internal combustion engine. An explosion will cause the pressure in the cylinder to rise far beyond the cylinder's design limits, before the force of the expanding gases can be absorbed by the piston traveling downward. This actually reduces power output, because much of the energy of combustion is absorbed as strain and heat in parts of the engine, rather than being converted to torque at the crankshaft.
High-performance engines typically have higher compression ratios and are therefore more prone to detonation, so they require higher octane fuel
Yeah, what HDX said:
Higher octane ratings correlate to higher activation energies. Activation energy is the amount of energy necessary to start a chemical reaction. Since higher octane fuels have higher activation energies, it is less likely that a given compression will cause detonation.
It might seem odd that fuels with higher octane ratings explode less easily and can therefore be used in more powerful engines. However, an explosion is not desired in an internal combustion engine. An explosion will cause the pressure in the cylinder to rise far beyond the cylinder's design limits, before the force of the expanding gases can be absorbed by the piston traveling downward. This actually reduces power output, because much of the energy of combustion is absorbed as strain and heat in parts of the engine, rather than being converted to torque at the crankshaft.
Calif-spyder
New member
I would be very surprised if the Spyder didn't have two octane tables in the tune.
I know for a fact that GM has been doing that at least since 2002,
it protects the engine from bad gas, if the computer detects knock or if it predicts knock might accure it will go to the lower octane tables and reduce timing,
BRP spent a lot of money developing the spyder and it looks like they went all out with sensors and electronics I don't see them skimping with the tune.
Mark
I know for a fact that GM has been doing that at least since 2002,
it protects the engine from bad gas, if the computer detects knock or if it predicts knock might accure it will go to the lower octane tables and reduce timing,
BRP spent a lot of money developing the spyder and it looks like they went all out with sensors and electronics I don't see them skimping with the tune.
Mark
SpyderDog65
New member
everyones a rocket scientist
87 or 91 who know everyones got a different opinion about it. the way i figure it. use what makes u happy cause everyone has a different opinion on the subject
87 or 91 who know everyones got a different opinion about it. the way i figure it. use what makes u happy cause everyone has a different opinion on the subject
throneroomdancer
New member
Scotty...just wanted you to know I've enjoyed your responses to the many posts since the Spyder forum began. You are a gold mine!
boogllasti
New member
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.
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.
NancysToy
Motorbike Professor
Actually, some get more power and mpg. My wife's Chevy HHR is one of them. Considerable improvement in power (not tested) and mpg (long-term records). This is a result of the engine management system. This thing will run on regular without knocking a bit. The computer adjusts it, and you don't notice any problems at all. It comes alive with premium, however, and the mileage goes up at least 2 mpg. Doesn't downshift as much in cruise control on the freeway, either. If you put 12,000 miles on a vehicle a year, and average 25 mpg, the cost is less than $100 more. Use what makes you happy, just don't expect miracles unless the vehicle is designed to need premium.
-Scotty
boogllasti
New member
Well, I guess we are just going to disagree on this. There are volumes of data available online about this subject that can educate you on octane.
When it comes down to it, since you are only using seat of the pants testing - if your Spyder engine is actually knocking with 87 - and NOT knocking with 91 - then I guess you have your answer.
Again, I've never heard of any Spyder having knocking issues - which is the only issue that higher octane addresses.
If better performance or MPG was available with higher octane - don't you think BRP would embrace this theory and promote it?
I fail to see how having an A&P applies to this situation, but I guess I'll just take your word that you know more than the BRP engineers and the volumes of data available online.
Most issues with engine 'sputter' on the Spyder have been due to running on a cold engine or having the VSS kick in. Higher octane won't cure either of those problems.
If you feel you're getting more bang for your buck with premium - by all means - keep spending that extra $$$ - I'm sure Exxon appreciates it.
Ride on - and enjoy!
Some like 91, the rest of us have no problems with 87.
I'll spend the extra $$$ on high-octane beer instead -
When it comes down to it, since you are only using seat of the pants testing - if your Spyder engine is actually knocking with 87 - and NOT knocking with 91 - then I guess you have your answer.
Again, I've never heard of any Spyder having knocking issues - which is the only issue that higher octane addresses.
If better performance or MPG was available with higher octane - don't you think BRP would embrace this theory and promote it?
I fail to see how having an A&P applies to this situation, but I guess I'll just take your word that you know more than the BRP engineers and the volumes of data available online.
Most issues with engine 'sputter' on the Spyder have been due to running on a cold engine or having the VSS kick in. Higher octane won't cure either of those problems.
If you feel you're getting more bang for your buck with premium - by all means - keep spending that extra $$$ - I'm sure Exxon appreciates it.
Ride on - and enjoy!
Some like 91, the rest of us have no problems with 87.
I'll spend the extra $$$ on high-octane beer instead -
boogllasti
New member
"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.
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.
SpyderMark
New member
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
boogllasti
New member
Well said Mark.
I think this horse is dead, perhaps from drinking the wrong octane or from having its timing retarded too much.
:bdh:
I think this horse is dead, perhaps from drinking the wrong octane or from having its timing retarded too much.
:bdh:
W
Way2Fast
Guest
There is a limit on how far the ignition timing can be retarded. A computer controlled "anti knock sensor" can not do miracles. It has to be designed to ONLY retard the timing to the point where decent drivability still exists. These days, with the high cost of gasoline, manufacturers who adverise that minimum regular 87 octane gas can be used add a selling point to their product. Will the vehicle run best on 87....not always. Given the Spyders high compression ratio I would not use any fuel under 93 octane in it.
boogllasti
New member
I found this previous post by Magic Man.
Hope this is okay to re-post?
Not sure what more proof one would need.
I also tried a tank of 93 and found it didn't run as well.
_________________________
From Magic Mans previous post:
The lower compression of this series of 990 Rotax as compaired to the 136hp version coupled with the higher flash point of the 93 octane fuel can actually make the Spyder have some driveability problems at lower RPMs. This we actually have experienced first hand in our own test on our Spyder last weekend.
We filled up an almost empty tank with 93 and drove the bike. After a few minutes when the 87 fuel was completely out of the fuel rail and lines the bike began to have a low speed "miss" or "stumble" that was not there before.
We went back to the shop siphoned out the fuel till no bars were shown went and refilled the tank with 87. Again after a few minutes when the fuel lines and rail were clear of the 93 the "miss" or "stumble" was gone.
There have been several automotive tests and service bulletins on this topic for just the same reason. The higher octane fuel can indeed cause drivability problem in todays engines designed to use the lower octane, lower flash point fuel. Higher octane fuel that is designed to "resist engine knock" or detonation, also has a reluctance to burn properly at low engine speeds because of the lower compression chamber pressures in todays low compression motors.
The higher a fuels octane number the greater it's resistance to pre-ignition it has. Diesel fuel has an octane number over 600 but would not even run in a Spyder as you all know. Unfortunately that higher octane of 93 fuel can also make the flame front spread too slowly in low compression motors causing these types of problems. Especially, at lower engine speeds when compression chamber pressures are at there lowest due to reduced volumetric efficiency of the motors at these engine speeds.
I did this test this last weekend to finally be sure once and for all that indeed it was running worse on the higher flash point 93, and to tell you the truth it really does not run as well at all.
________________________________
Hope this is okay to re-post?
Not sure what more proof one would need.
I also tried a tank of 93 and found it didn't run as well.
_________________________
From Magic Mans previous post:
The lower compression of this series of 990 Rotax as compaired to the 136hp version coupled with the higher flash point of the 93 octane fuel can actually make the Spyder have some driveability problems at lower RPMs. This we actually have experienced first hand in our own test on our Spyder last weekend.
We filled up an almost empty tank with 93 and drove the bike. After a few minutes when the 87 fuel was completely out of the fuel rail and lines the bike began to have a low speed "miss" or "stumble" that was not there before.
We went back to the shop siphoned out the fuel till no bars were shown went and refilled the tank with 87. Again after a few minutes when the fuel lines and rail were clear of the 93 the "miss" or "stumble" was gone.
There have been several automotive tests and service bulletins on this topic for just the same reason. The higher octane fuel can indeed cause drivability problem in todays engines designed to use the lower octane, lower flash point fuel. Higher octane fuel that is designed to "resist engine knock" or detonation, also has a reluctance to burn properly at low engine speeds because of the lower compression chamber pressures in todays low compression motors.
The higher a fuels octane number the greater it's resistance to pre-ignition it has. Diesel fuel has an octane number over 600 but would not even run in a Spyder as you all know. Unfortunately that higher octane of 93 fuel can also make the flame front spread too slowly in low compression motors causing these types of problems. Especially, at lower engine speeds when compression chamber pressures are at there lowest due to reduced volumetric efficiency of the motors at these engine speeds.
I did this test this last weekend to finally be sure once and for all that indeed it was running worse on the higher flash point 93, and to tell you the truth it really does not run as well at all.
________________________________
Calif-spyder
New member
I was going to suggest someone look to see if there is a knock sensor part number. I am VERY, VERY disappointed that BRP doesn't have knock protection, for as much as we are paying for these bikes and the technology they did put into it I think they dropped the ball big time.I have it on good authority that the factory system DOES NOT have knock detection.I also checked the parts book and no knock sensor that I could find.
since the spyders don't have knock protection I will put higher octane fuel in my bike.
Mark
Calif-spyder
New member
when I get my spyder I will take it to the race track and run the 1/4 mile with both 87 and 91 octane, I will also look for driveability on the way to the track
Mark
Mark
Where did you hear that about the HEMI??? I've got an '05 300C HEMI which I've owned since new and I assure you that all 16 of those plugs are firing....except when the multi-displacement system (which your truck doesn't have btw) cuts out 4 of the cylinders.:dontknow:
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