Another gasoline thread

[GreenMachine]

I have been doing a little reading on Wikipedia about Octane, RON, MON, AKI, etc.  Very interesting.  Turns out European fuel is different than most fuels used in North America.  Theirs is based on RON and ours (U.S./Canada/Brazil) is based on AKI, which is (RON + MON)/2.

Interesting food for thought, especially when I was able to confirm what perhaps others have read or understand about AKI.  If you have an engine, for instance a race engine, with a lot of ignition advance, it must use a higher octane fuel.  We all know that.  However, general purpose engines without ignitions able to advance timing to the same degree, may actually perform worse using higher octane fuels:

"Octane rating does not relate to the energy content of the fuel (see heating value). It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where the octane number is raised by blending in ethanol, energy content per volume is reduced."
Something to consider before putting V-Power Premium in your vehicle then espousing how much more powerful she feels.   

p.s. it's on the Internet, so it must be true! In this case, it looks to actually be accurate.

[dub]

I don't know what's worse: People buying premium because they think they are getting better performance or people who ignore the manufacturers recommendation for premium on a high compression/forced induction motor because they think they are saving money.

[GreenMachine]

You're absolutely right.  Forced induction (turbo/supercharged) engines should be fed whatever the manufacturer recommends. 

On a normally aspirated  engine however,  so long as they're not getting pre-ignition, technically they're doing themselves a favor by matching the correct fuel to their engine's atmospheric conditions, regardless of recommendation.  For instance, take residents of the Truckee Meadows.  Our base elevation is 4,500.'  Technically, if the engine recommendation is for 89 or 91, using 85 or 87 shouldn't be a problem.  In fact, in SLC, Utah, many stations supply 85 octane for this reason.  Because they can.  Same reason you'll find it here too, but typically only at bargain gas stations. 

Kwak says my bikes should use 90+ AKI.  With the exception of the height of the Summer months (July/Aug), I've been using 89 and 87 exclusively.  Haven't observed knocking.  A couple weekends ago n10sive and I stress tested the 89 octane I had in my tank.  It passed with flying colors.