Thread: Premium Fuel?
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Old 02-22-2013, 02:16 PM   #2
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Location: Tucson, AZ
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Do you have a ScanGauge-II™ or something similar (OBD-II bus reader)? If you do, then you can "test" your hypothesis yourself by checking ignition advance degree readings on each octane while driving over the same roadway.

If you find the ECM consistently applys more advance on the 93 octane fuel than you saw on the 87 octane, that's a good indication you're getting more POWER. Fuel economy should improve too, but octane is not the same as energy content (BTU's), which varies little, except for the summer vs. winter blend differences.

Unfortunately, these "tests" will be impossible to do back-to-back (ie: A-B-A) because you have to empty the tank each time. However, you can shorten the turn-around cycle by running the tank down almost to empty (let the lamp come on) on 87 octane--do your test--then fill-up with 93 octane and repeat the test...but that'll only be half of the desired scientific A-B-A test methodology. Also, all the old fuel already in the fuel system plumbing must be used up before the new fuel effects will become detectable.

A mixture of 2 gallons of 87 octane combined with 13.6 gallons of 93 octane is a mixture ratio of 87%...but should be 'close enuf.'
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Last edited by 70AARCUDA; 02-22-2013 at 02:57 PM.
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