Thread: 91 Octane
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Old 11-09-2012, 02:36 PM   #5
blue2000s
Porscheectomy
 
Join Date: Mar 2006
Location: Seattle Area
Posts: 3,011
Quote:
Originally Posted by BYprodriver View Post
How does the altitude alter the fuel octane rating?
It's a matter of air density. Because there are fewer molecules of air and fuel to rub against each other in a combustion chamber at altitude, the tendency to auto-ignite is lower. Thus the lower octane number because it's correct for the altitude where it is sold, and the lower octane requirement.

Last edited by blue2000s; 11-14-2012 at 11:04 AM.
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