Joe Merone wrote:
>
> >John Lye said:
> >There are two methods for measuring octane rating,
> >research and motor.
>
> Actually the m stands for marine. Today's octane ratings are arrived
> at by adding r plus m and then dividing by 2.
>
> Joe Merone
> CF 18928
The "R" and "M" are for research and measured. I've
excerpted a portion of Bruce Hamilton's excellent (and
lengthy) Gasoline FAQ:
==============
6.4 Why are two ratings used to obtain the
pump rating?
The correct name for the (RON+MON)/2 formula is the
"antiknock index", and it remains the most important quality
criteria for motorists [25].
The initial octane method developed in the 1920s was the
Motor Octane method and, over several decades, a large
number of octane test methods appeared. These were
variations to either the engine design, or the specified
operating conditions [65]. During the 1950-1960s attempts
were made to internationally standardise and reduce the
number of Octane Rating test procedures.
During the late 1930s - mid 1960s, the Research method
became the important rating because it more closely
represented the octane requirements of the motorist using the
fuels/vehicles/roads then available. In the late 1960s German
automakers discovered their engines were destroying
themselves on long Autobahn runs, even though the
Research Octane was within specification. They discovered
that either the MON or the Sensitivity ( the numerical
difference between the RON and MON numbers ) also had
to be specified. Today it is accepted that no one octane rating
covers all use. In fact, during 1994, there have been
increasing concerns in Europe about the high Sensitivity of
some commercially-available unleaded fuels.
The design of the engine and car significantly affect the fuel
octane requirement for both RON and MON. In the 1930s,
most vehicles would run on the specified Research Octane
fuel, almost regardless of the Motor Octane, whereas most
1990s engines have a 'severity" of one, which means the
engine is unlikely to knock if a changes of one RON is
matched by an equal and opposite change of MON [19].
==============
--
Kenneth B. Streeter | EMAIL: streeter@sanders.com
Sanders, PTP2-A001 |
PO Box 868 | Voice: (603) 885-9604
Nashua, NH 03061 | Fax: (603) 885-0631
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