8th Generation Honda Civic Forum - View Single Post - SI with 87 octane gas *Threads merged*
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Old 09-22-2008, 10:35 PM   #54 (permalink)
soxfan143
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Mike
Octane is directly related to burn efficiency. The lower the octane the easier the fuel will ignite under pressure and possibly ignite prematurely. Premature ignition as also known as the dreaded knock. Now with a high compression motor like the Si the compression in the chamber on the compression stroke is way too much for 87 octane fuel. And with the high ignition timing this car runs on, the 87 octane gas is a recipe for disaster. You WILL get detonation from this. You might not hear it and the knock sensor will retard timing enough for you not to cause significant damage. But I would not run 87 octane ever in this car.
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