Using 93 octane in the mazda 3 - Page 3

Dec 23, 2009 | 03:44 PM

#51

zoom44

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From: portland oregon

thats just wrong. plain and simple backwards.

you dont run more advance because you are using a higher octane - Higher octane ALLOWS you to use more advance. When you advance the Ignition timing you are going to run leaner. leaner conditions cause higher heat. higher heat can cause knock. you change to a higher octane to keep from knocking.

take another look- not all were racing fuel producers. crane cams. motorcycle and other forums. the gasoline faq. pcm prgramming pdf. books on combustion.i could have put up the various iso-octane papers that result from quick google searches but whatst teh point when no one will read them?

you keep saying "leaded" when referring to race fuels but there are many fine 100 octane fuels that are neither leaded nor oxygenated

Dec 23, 2009 | 04:51 PM

#52

b'Eight'

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From: PA

Here's a good read:

http://tinyurl.com/OctaneShootout

Dec 23, 2009 | 05:05 PM

#53

zoom44

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From: portland oregon

wow imagine that octane has nothign to do with power

Quote:

Why hadn’t more timing increased power? Probably because the 114 had even better burn characteristics than the 100. Its hydrocarbons vaporized and burned more readily, releasing energy sooner and accounting for why it required less spark lead to reach complete combustion. The octane level was not the operative here—rather it was the superior hydrocarbon content and vaporization characteristics of the racing fuel. See Test 6 in the sidebar below.

and they found that higher octane=slower burn to be incorrect

Quote:

But most of all, we discovered that our presumption that higher-octane fuels burn slower than lower-octane fuels (and therefore require more ignition lead) is largely incorrect. There are too many other fuel-formulation issues at work to assign a general rule about octane.

Dec 23, 2009 | 05:11 PM

#54

b'Eight'

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From: PA

But you're missing the point. They had to start playing with 114 octane fuels which you can't run in your street automobile that changed the rule of thumb.

Dec 23, 2009 | 05:14 PM

#55

zoom44

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From: portland oregon

no you have missed the facts. it said the same thing as every other source i have quoted you and more- octane and the speed of the burn are not correlated.

Jan 17, 2010 | 08:15 AM

#56

PNTitBLK_07

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My understanding (limited as it may be) is that rather then slower burn time, higher octane fuels actually have more resistance to ingition than lower octane fuels ( i am not sure as to why). this can help prevent unwanted detonation because it is less likely to ignite from hot engine temps and high compression.

this helps our cars because ill timed fuel ignition can easily lead to apex seal damage.

am i close on this or is my perception a little too simplified?