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Posted by PGAero [Email] (#1143) [Profile/Gallery] (more from PGAero) on Thu, 9 Jul 2009 11:16:30 Share Post by Email
In Reply to: I know higher octane increases knock resistance, Noel, Thu, 9 Jul 2009 11:03:45
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I know you know that, Noel. I was prompted to respond to the comment that the valve timing is altered... then I got carried away.

Here's my take on the "higher energy density" line. The additive which increases octane rating is not a combustible energy source. Since higher octane fuels have more of the additive, then there is less hydrocarbon per volume, which causes the energy density to be lower. The actual extend to which the energy density is changed is something I don't know. I suspect it's almost negligible, but I'm not sure. FYI, I am an engineer, but not in the field of energy/fuels/automotive. Just a lowly ME and CE by education, and CE by license.

Cheers,
~Peter

posted by 69.230.1... 
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