[FWDLK] octane ratings

[van Hoy <vanhilla@xxxxxxxxxxxx>]

Perhaps someone out there can enlighten the masses about
octane ratings.  I know that the octane in the good old days
was rated differently than the present method which is
RON+MON/2.

I did a very little research and learned that the Research
Octane method was invented in the 1920's and the RON
[Research Octane Number] per se has been used since 1942 and
formally approved in 1947.  The MON [Motor Octane Number]
was developed in the 1930's as the ATSM.

One source [www.repairfaq.org/filpg/AUTO/F_Gasoline6.html]
stated that in the 1930's cars would run better or worse
depending upon the RON with almost any MON, but that modern
cars are effected most by the "severity," which is the
difference between RON and MON.  [ie a change of 1 RON
matched by an equal opposite change of MON will apparently
result in the same knock propensity or lack thereof.

It doesn't take a rocket scientist to deduce that we can't
easily tell the difference between RON and MON using the
current adding/dividing method.  Do we need to for our old
cars?  Maybe we should be buying gasoline like a fine wine,
checking all the ratings to determine the best for our car's
pallette.  Does the RON rating itself apply better to a
1950's car?  Where between 1930's and 1990's did the change
in engine gasoline demands occur?

Anyone with more knowledge care to share with the group?  A
little knowledge is a dangerous thing.

--Roger van Hoy, '55DeSoto, '42DeSoto, '66Plymouth,
'73Duster, '81 Imperial, Washougal, WA|