Some say that you only need enough to keep it from pinging, but I run 93 in everything I own. My MDX (acura) runs very well on 93, but I tried a tankfull of 91 and the MPG went down and the performance dropped off a bit, so 93 it is for me. Conversly some say in the winter to use a lower octane for a slower burn but I still use the 93 year round. Some things are hard to change.
I've been running 87 octane, but I wanted to know if any of you have noticed a difference when you run a higher grade petrol?
Doesn't the manual say to use at least 91 octane?
Here is ROUGHLY the way it works, lower compression lower octane, higher compressin higher octane.
In my bike, I run 93 octane because there's no 91 around here and 93 is all they have. If there was 91 around here, then I would still probably run 93 octane.
You might be able to notice a difference on the octane you run if you have EFI. Some computers compensate for the fuel your running. For example, a 4.3L Vortec engine (car) will produce much more power on higher octane. My Honda civic will get 20mpg when I run 87 octane in it. When I put 93 octane in it, then it will get 26mpg and it feels like it produces more power. Either way acceleration is much smoother on the higher octane fuel.
Some people have said that they see worse/no results putting a higher octane fuel into a low compression engine.
What octane to use? The one where your engine doesn't ping.
A lot of it has to do with the compression ratio your engine has, 9 to 1 and above at least 93 Octane, what most people don't realize is that the higher the octane number the cooler the burn is, the lower octane burns hotter, the EPA had a lot to do with this and this is why most modern engines don't have higher compression engines, to meet EPA emisson cleaner burning engines, and they actually run better on the lower octane fuel for which they were designed for with the lower compression. One rule of thumb, high performance, high compression, high octane. On a bike, 10.5 to 1 is about as high as one should go and still be o-k if you can't get 93 at some remote station.
There is a lot more scientific info on this subject. I just skimmed the top.
Any body in my catagory and remember the VW bug, I did a lot of work on them and they requires 91 octane in the owners manual back then early 70's. I had a 73 toyota corolla 4 speed back in 75 that was a real dog of a car on regular gas, 1.4 engine I think. I tried one day putting in hi test and the darn thing flew, it spun the tires and all, I just couldn't believe the difference in that car. Still don't to this day.
The gas companies must love you fellas. Lowest octane that does not ping heavily under load will get the best mileage/dollar (as noted above, some engines with good knock sensors can make a bit more power with higher octane). Sure can't explain the results with the bug tho???
Which octane do you prefer in your V-twin?
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