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On 2001-12-17 11:57, CA_Bullitt wrote:
An octane rating is "resistance to combustion." The higher the rating, the harder (longer it takes) for the fuel to combust.</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR></TD></TR></TABLE>
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Octane rating is "the resistance to DETONATION, not the "resitance to combustion".
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If you are noticing a higher gas miledge with higher octane, then that generally means you are getting incomplete combustion with the lower octanes.
This is just wrong, sorry. :smile:
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Timing is the key that determines what octane level a car should be running. That and compression ratio. Higher octane gas burns slower and more evenly across the combustion chamber which is why it is not recommended in our cars with the current stock timing set up. It is necessary to run timing more advanced so that the fuel burns completely with high octane and using low octane fuel with advanced timing causes the engine to 'ping' or 'detonate'. Our engines, starting in 2001, had the compression ratio upped to 9.4:1 from 9:1. This, I believe, is why the earlier Bullitts were having pinging issues early on and the fix was to retard the timing by reprogramming or changing the computer. Using a chip on the other hand forces you to use higher octane fuel for the reasons said before, the timing is advanced (fuel curves also changed)and thus the need to use higher octane fuel. :grin:
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Bullitt #5338 - No mods necessary at this time! Ok, maybe a K&N filter
<font size=-1>[ This Message was edited by: 1NastyFordGT on 2001-12-26 19:52 ]</font>