| Author | Message | ||
     Matty7092 |
I was at a gas station today and noticed a separate pump with 110 octane gas. Now, would this gas do more harm than good in my bike(xb9s). And would I notice any difference performance wise. I didn't look to see how much it cost, but 91 octane was $2.17 a gallon, so I stuck with that. Any help on this matter would be greatly appreciated. Matt | ||
| Eexb |
110 Octane is racing gas, better used in higher compression motors (12.0 to 1 or higher). You won't recognize any gain(s) from using gas w/ octane higher than recommended in your owner's manual. I'll bet 110 is close to $5.00 a gallon these days. EE | ||
| Slaughter |
With stock compression, you will most likely LOSE power with that 110 octane. Higher octane takes more energy to ignite (higher compression) but mainly helps prevent detonation in higher compression engines. Save your money. True race gas with similar octane - such as VP U4 (Ultima 4) - 92 octane is probably the most used race gas. It can give more power because of the additives NOT in the mix. It is leaded however. | ||
| Djkaplan |
"With stock compression, you will most likely LOSE power with that 110 octane. Higher octane takes more energy to ignite (higher compression) but mainly helps prevent detonation in higher compression engines." I have heard this time and time again, but have yet to hear a clear explanation of why this might be. Unless you're a petrochemical engineer, I'd look at any arguments with a jaundiced eye. | ||
| Scitz |
Maybe the higher compression changes the flash point of the air\fuel mixture. The higher octaine may burn longer and is then better for higher compression. I think that using to high of an octane may cause carbon build up in the cylinder because all the full is not burning off. I'm not sure if this is true or not but seems to be what I've heard over the years. | ||
| Gowindward |
Looks like some real facts here: http://blizzard.rwic.und.edu/~nordlie/cars/gasoline.html | ||
| Matty7092 |
It seems I remember someone on the board saying not to use high octane gas before but I wasn't sure. Do most people use 91 octane, or can I get by with 87 which is medium grade here in Colo.? Matt | ||
| Charlieboy6649 |
RTFM! LOL! It says to use 91... | ||
| Fullpower |
Ran a compression test on stock XB12 yesterday. 10500 miles, cold engine, front 160 PSI, rear 150 PSI. I dont see a need for any more than 91 octane in these engines. mine runs very happily on 87. only time i can ever get it to ping even slightly is when slow racing at rodeo games. | ||
| Jlnance |
I have heard this time and time again, but have yet to hear a clear explanation of why this might be. Higher octane gas is more difficult to ignite. The reason it is used is because you can get the mixture inside the cylinder hotter and it won't explode (knock). Explosions inside the cylinder are bad, you want a controlled burn. Being able to have higher tempratures in the cylinder and still have controlled burning allows things to be done to make the engine more efficient and powerful (ie, better compression ratio). Higher octane fuels allow changes to be made in engine design. If your engine does not need it, the major reason for using it is gone. I don't know if the power of the engine would actually go down if you used higher octane fuel. That depends on how much energy is released by burning it. That number is call the "heat of combustion." I googled for some numbers and didn't find anything useful. | ||
| Unibear12r |
My XB12R didn't like 87 octane at all! Then again that was in Death Valley in July.  I stick with Premium Unleaded. | ||
| Tank_bueller |
Sure it will help the bike!!! After he pays for the 110, his wallet will be so much lighter..............you get the point. sorry, I,m home alone and crackin' myself up at somebody elses expense.....I should just go to bed. | ||
| Djkaplan |
Maybe the higher compression changes the flash point of the air\fuel mixture. The higher octaine may burn longer and is then better for higher compression. I think that using to high of an octane may cause carbon build up in the cylinder because all the full is not burning off. I'm not sure if this is true or not but seems to be what I've heard over the years. Well..., this is the answer I was hoping to avoid. | ||
| Scitz |
Here's some info from the link above. thanks for posting Gowindward. 6.2 Why do we need Octane Ratings? To obtain the maximum energy from the gasoline, the compressed fuel/air mixture inside the combustion chamber needs to burn evenly, propagating out from the spark plug until all the fuel is consumed. This would deliver an optimum power stroke. In real life, a series of pre-flame reactions will occur in the unburnt "end gases" in the combustion chamber before the flame front arrives. If these reactions form molecules or species that can autoignite before the flame front arrives, knock will occur [13,14]. Simply put, the octane rating of the fuel reflects the ability of the unburnt end gases to resist spontaneous autoignition under the engine test conditions used. If autoignition occurs, it results in an extremely rapid pressure rise, as both the desired spark-initiated flame front, and the undesired autoignited end gas flames are expanding. The combined pressure peak arrives slightly ahead of the normal operating pressure peak, leading to a loss of power and eventual overheating. The end gas pressure waves are superimposed on the main pressure wave, leading to a sawtooth pattern of pressure oscillations that create the "knocking" sound. The combination of intense pressure waves and overheating can induce piston failure in a few minutes. Knock and preignition are both favoured by high temperatures, so one may lead to the other. Under high-speed conditions knock can lead to preignition, which then accelerates engine destruction [17]. 6.13 Can higher octane fuels give me more power? Not if you are already using the proper octane fuel. The engine will be already operating at optimum settings, and a higher octane should have no effect on the management system. Your driveability and fuel economy will remain the same. The higher octane fuel costs more, so you are just throwing money away. If you are already using a fuel with an octane rating slightly below the optimum, then using a higher octane fuel will cause the engine management system to move to the optimum settings, possibly resulting in both increased power and improved fuel economy. You may be able to change octanes between seasons ( reduce octane in winter ) to obtain the most cost-effective fuel without loss of driveability. Once you have identified the fuel that keeps the engine at optimum settings, there is no advantage in moving to an even higher octane fuel. The manufacturer's recommendation is conservative, so you may be able to carefully reduce the fuel octane. The penalty for getting it badly wrong, and not realising that you have, could be expensive engine damage. | ||
| Djkaplan |
...using a higher octane fuel will cause the engine management system to move to the optimum settings, possibly resulting in both increased power and improved fuel economy. Okay. Just what is the exact point you were trying to make with your original post and this reply? | ||
| Cmm213 |
If you stick to regular 92 93 94 octane pump gas these motors should run fine. I did ocasionaly run 100 unleaded through my gxrs years back and they ran very smooth at idle. I have a highly modded awd talon that gets only 100 or higher, it gets vp116 leaded at the track- no detonation at all plus I run 22# of boost to it- race fuels to me are for forced induction motors to fight of knock problems. kinda like a safe guard for me | ||
| Fullpower |
what exactly does a water cooled turbocharged automotive engine have to do with the discussion of octane requirements for a stock XB? with cranking pressure around 160 PSI the octane requirements of these bikes, while somewhat dependent on ambient temperature, are easily met with normal unleaded automotive pump gasoline. the manual calls for 91 octane, which is probably a good starting point for your experimentation. | ||
| Charlieboy6649 |
Fullpower makes a very valid point verified by my climate. I always run 91 oct but get a lot of (marbles rolling around in the engine noise) when it's above 100 deg and under acceleration. When it's 100-130 degrees here, I wish I could find higher octane. I just baby the throttle when it's hot. |
