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Old 11-09-2003, 07:36 PM   #1
Scooby Newbie
Member#: 14727
Join Date: Jan 2002
2002 impreza RS

Default Can octane requirement be calculated?

If one was "building up" a NA 2.5 motor and wanted a higher compression ratio, would there be a way of calculating the octane level of the fuel required to run the engine without damage? Or to word it another way, knowing that 11:1 is good for 87 octane, how hight of a compression ratio could one go using 93 octane as the minimum?
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PeterJ is offline   Reply With Quote
Old 11-09-2003, 08:59 PM   #2
Scooby Specialist
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Join Date: Mar 2003
Chapter/Region: South East
Location: Atlanta
2013 No gears!
Saltine American


11:1 and 87 octane? Are you nutz?
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Old 11-09-2003, 10:48 PM   #3
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Member#: 14727
Join Date: Jan 2002
2002 impreza RS


Isn't that what a 2.5RS is at? Or did I mean 10:1... oops.
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Old 11-14-2003, 08:45 AM   #4
Section 8
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you cannot calculate octane requirements. You can calculate compression ration before hand though. Most people will not run more than 11:1 on 93 octane, others even less.

Other things come into play for detonation resistance of an engine, such as quench, timing, anything not quite right in the cylinder/combustion chamber ect. You can play with timing, but eventualy you run into a point where you can raise the comprssion, but you loose timing so you gain nothing.


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