Yamaha Raptor Forum - View Single Post - "Octane for dummies"
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post #13 of (permalink) Old 05-05-2007, 11:44 PM Thread Starter
rt
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Re: "Octane for dummies"

those are static numbers, in reality when your motor is running a 11:1 with a cam its actually pushing out around 8:1 to 9:1 at the most. so for your 11:1 static it should run (8:1 dynamic) or so. which means you should only need 92-93 or so octane..find 94 and 11.5:1 is likely, run a very aggressive cam with high flow porting and its possible to run a 12:1 on 94 octane (which is still pump in most states, sunoco). Every motor is different, therefore requires a different dynamic compression. although static compression remains the same regardless.
dynamic comp. for a 9.2:1 is around 7:1

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