> Well, I am not too sure that octane influences the propagation of
> the flame
> front, but octane rating does affect your ability to get your engine to
> perform.
For more than you ever wanted to know about octane ratings, see
http://www.faqs.org/faqs/autos/gasoline-faq/part3/
There is an interesting chart there, which I've attempted to reproduce :
Basic Ignition Timing
Vehicle Retarded Advanced
5 degrees Standard 5 degrees
A 88 91 93
B 86 90.5 94.5
C 85.5 88 90
D 84 87.5 91
E 82.5 87 90
This suggests that retarding your timing by 5 degrees may "buy" you the
equivalent of 3-4 octane points.
There's also some hints on jazzing up your octane rating ... including the
observation that it's not cost-effective.
Randall
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