octane formula for compression?

Old 04-08-2004, 07:03 PM
tastyklair is offline
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octane formula for compression?

Is there a formula for determining the need octane for a given cr. If there is does it take into account the dynamic compression ratio or only the static? Is there a quick table somewhere that shows the relationships like a spreadsheet?
Old 04-09-2004, 10:00 AM
Mike G
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My engine comes up with it's own formula, unfortunately it usually wants more octane... It also will depend on load and altitude and things like that. If you are running around 9.5:1, you should be safe with regular fuel. Other than that, your engine will tell you what it needs.

Old 04-11-2004, 03:14 PM
mlf72f250 is offline
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Here's a list of things that affect octane requirement
carbon deposit levels
manual or automatic tranny
air temperature
water temperature
iron or aluminum heads
bore diameter
spark timing
boost level
EGR level
number and location of spark plugs
sharp edges/hot spots
and I've probably forgotten some

Here's a good link:
look under "Octane Number Requirement and Octane Requirement Increase"

Look at the table in Figure 5-9.

Last edited by mlf72f250; 04-11-2004 at 03:17 PM.

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