I'm with you, or +1 (which the site didn't like).

 

Well since I've posted in this thread a while ago I've been trying a higher octane fuel. So far my mpg has gone from 56 to 48 switching from 87 to 89 octane. It was to my surprise it went down but my intention was originally to see how the bike performs. I keep track of my mpg just for grins and noticed the change on the first tank. I'll report back later on but I'll be more scientific about it over the next few tanks to rule out as much variables as possible. It's been all normal around town riding and admittedly I've probably been mashing the throttle more to see how it responds but even when I ride a lot of aggressive dirt I rarely see below 53 mpg.

 

Don't try to confuse us with facts, does your butt say it's faster or slower?


I can't believe anyone can think octane cools an engine. The cooling system does that, oil helps a bit, but in the end it is the cooling system. If your engine runs too hot the cooling system is the problem. It is what cools the engine. Cooling the engine cools the oil in the engine and also cools the combustion chamber and piston (heat transfer through rings to the cylinder wall and also oil).

The gas ignites the gas burns the difference is higher octane is harder to ignite. Makes it less likely to detonate and guess what causes detonation... heat. So higher octane allows the combustion chamber to run a bit hotter without the mix igniting too early due to heat of compression. Yes, heat of compression, seems when gasses are compressed they tend to generate heat.

So any number of myths about octane can be believed, but facts are facts. And one more fact - race gas is a totally different blend of fuel than pump gas. As I pointed out earlier, there actually is 87 octane high performance race gas, because some racing series require specific octanes. They get better performance with the same octane, so now you know why a splash of race gas helps a bit. A splash of nitro might do the same thing too.

 

Higher octanrs burn hotter. If you feel like you running real hot you probablytoo lean

 

Matt, where's your proof higher octane burns hotter?

Does premium unleaded burn hotter than regular | Mechanical /Maintenance Forum | Bob Is The Oil Guy

 

Test Results


More Octane For More Power? | Mythbusters | Super Streetbike

 

I'm guilty of the "run hotter" thing... I speculated that the chamber might run a bit hotter when fuel doesn't ignite until a higher temp. In retrospect that difference is probably so small it is irrelevant in comparison to actual combustion chamber temperature developed by combustion. The rise in temperature to fire the fuel is probably a few hundred degrees versus the combustion temperature which is probably around 1700 dF or so. I didn't look that up, but exhaust temps run around there, so certainly combustion must be near that too.

But boy, talk about two good sources, one from Bob is the oil guy (oil company sponsored) and Super Street Bike! I think this whole "octane increases performance" saying octane alone increases performance is shot in the buttocks! There has to be a mechanical or fluid power need for increased octane to actually gain performance.

 

This isn't about higher octane burning hotter, but still a good little bit of info.

https://mn.gov/commerce/weights-and-...ctaneFacts.pdf