Steve & Eileen Genotte wrote:
>I am not familiar with European ratings for autogas. What is the octane
>of "4 star" gasoline?
Steve - I think many people who use 4-star would not be able to answer that
straight off. My excuse is that I've been driving diesels since 1987. The
answer to your question is found in British Standard 4040, originally
published 1967, and revised a few times since. The most recent issue I've
found is 1988. It specifies a whole load of stuff about the composition of
the fuel (contaminants, lead content, etc) and its volatility as well as
the anti-knock rating. It mentions two rating systems: Research Octane
Number, and Motor Octane Number. I think that RON may be the most universal
currency (certainly that was the rating commonly quoted in UK before BS4040
came out), but you might want to set BS4040 beside the appropriate SAE
document and see if there are significant differences in methods or
calibration. (A good public library should have all this stuff on fiche or
CD-ROM.) After this Standard came into use, octane ratings were hardly ever
quoted, pumps were just marked with the star rating.
BS4040 RON MON
2-star 90.0 80.0
3-star 93.0 82.0
4-star 97.0 86.0
There was also a 5-star grade which I think was 100-octane or slightly
higher (RON).
This all refers to LEADED petrol (motor spirit / gasoline). Unleaded stuff
is specified in BS7070 which I can't get hold of at the moment.
HTH
cheers
Rowland
... that's Rowland with a 'w' ...
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