Quote Originally Posted by OkiePoke View Post
I think the difference you are noticing is because of the 100% gas, not the octane difference. Higher octance actually has less energy per gallon. Octane is there to reduce detonation in your engine. High performance cars run it because they tune for it to change the timing of the engine, creating more horsepower.

Edit: The best thing to use is whatever your car manufacturer calls for to use.
Kind of. Higher octane is used to prevent pre-ignition. High compression ratio engines need higher octane so you can get a proper concentration of fuel inside the cyclinder before it fires. Low octane fuel will ignite before the spark plug fires (the cylinder head is hot enough to spontaneously combust the fuel before the spark plug fires) creating knocking. High octane will not do that. You get more power out of high octane fuel because you are getting the proper mixture of gas in the cylinder before ignition. (Around 20-25 degrees before top dead center on the compression stroke.)