The premuim octane of 98 is "research method". There are several different
methods of measuring octane and I believe the one used in the US produces
slightly lower number, through the "motor method" measurement. Thus I have
believed over the years that the 98 octane was roughly equivalent to 92-94
on the US pumps. My check of some of my ASTM literature verifies the
different measurements but does not mention how the measurements vary.
To make things more complicated, those octane requirements apply at sea
level. At higher elevations, you can get by on lower octane ratings. Thus
here in the Rocky Mountain region, 88 octane is considered as "high
octane", 85 is "normal". Although 92 can be found at a much higher cost at
some gas stations. I notice on my trips back east that higher octane fuel
is much more abundant. Much to my surprise, both my MGs don't seem to mind
the 88 octane.
David
67 BGT
71 BGT
At 09:59 PM 5/17/00 -0400, BobMGT@aol.com wrote:
>The owners manual for my '71 specifies "Premium 98 or above". This is a far
>cry from 92. (Or is this apples and oranges, old/new octane numbers?) I
>personally run octane booster. I can run 15 deg BTDC @1500 rpm like the book
>says and I get less run-on. Let the flames begin. (Does John Twist have an
>opinion on this?)
>
>Bob Donahue (Still stuck in the '50s)
>EMAIL - BOBMGT@AOL.COM
>52 MGTD - under DIY restoration NEMGTR #11470
>71 MGB - AMGBA #96-12029, NAMGBR #7-3336
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