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EBass

Octane Q?

8 posts in this topic

Just wondering what Octane people use. I have an 88 25H Merc and I've been running it with the higher octane 92/93. Is that OK, or will she burn up?

This is my first boat so I have no clue! Thanks FM Members!!

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Unless you are looking for peak (racing) performance, I think you can run with unleaded just fine.

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E-bass,

Most outboard engine manufacturers recommend an 87-89 octane fuel be run in their engines.

Higher octane requires higher compression and more firing power to ignite the fuel. It sounds like you are doing alright on it, but some folks find with higher octane gasolines they foul plugs alot easier.

I would suggest going back to a regular grade octane gasoline. It will save you money and performance should still be more then satisfactory.

Just my .02.

------------------
Good fishing,
UJ
unitedjigsticker@aol.com

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My '99 115hp runs terrible on higher octane gas. The manufacturer recommended 87 and it runs best on this fuel. I could care less if it has ethanol in it as it has never been a problem in any of the 34 cylinders I own smile.gif

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Thanks for the info fellas. I'll switch back to 87. Too bad I just filled her up with 93. Whoops smile.gif

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This questions comes up frequently, especially in regard to two stroke motors.

Octane is simply the measurement of gasolines resistance to detonation.

Higher octane does not mean that it burns hotter, or has higher performance.

Most normally aspirated engines will run fine on any fuel you can get at the pumps in the 87 to 93 octane range.

Many folks run the higher octane fuel as some stations have one pump that has un-oxygenated fuel. This pump is typically the highest octane. This fuel will have no ethanonl added that can cause seal and o-ring troubles in older engines.

I have seen snomobilers put 100 Low Lead in a factory engine, and they were fouling plugs left and right. This engine simply did not have enough compression to efficiently burn the higher octane fuel. It did no harm, it just made their sleds run excessivly rich.

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Holy Cow Batman!

I don't know how long it would take me to read the information in the link and comprehend most of it. I'd have to read it very, very slowly.

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