American octane ratings

[Mathew]

Hey Fletch ,you out there?

A while back you emailed the list with info on what the American octane ratings work out to be in NZ ratings. The list search engine is down and I can't be bother manually scrolling through them all so...
What does the American 92 and 93 fuels work out to be in NZ octane ratings?

[jeff]

try this:
http://www.med.govt.nz/ers/oil_pet/fuel ... P104_14527

basically we use RON, US uses (RON+MON)/2 ... someone else will have to chip in with conversions between the two !
Mathew <matt@deepvideo.com> wrote: Hey Fletch ,you out there?

A while back you emailed the list with info on what the American octane ratings work out to be in NZ ratings. The list search engine is down and I can't be bother manually scrolling through them all so...
What does the American 92 and 93 fuels work out to be in NZ octane ratings?

[Don Warrington]

I've reproduced Fletch's December email on octane ratings below (hope you
don't mind, Fletch!). A quick web search shows that there is no guaranteed
relationship between RON and MON, but for typical auto fuels, a rule of
thumb is that RON is 8-10 points higher than MON, so that the US "pump
octane" rating of

"antiknock index" AKI = (RON+MON)/2

is 4-5 points less than the NZ RON rating. See for example:

www.eaa.org/education/fuel/detonation.html
www.ibmwr.org/otech/octane.html

Don
--------------------------------

basically we use RON, US uses (RON+MON)/2 ... someone else will have to

chip in with conversions between the two !

Mathew <matt@deepvideo.com> wrote: Hey Fletch ,you out there?

A while back you emailed the list with info on what the American octane

ratings work out to be in NZ ratings. The list search engine is down and I
can't be bother manually scrolling through them all so...

What does the American 92 and 93 fuels work out to be in NZ octane ratings?

--------------------------------------------------
From: "Fletcher Blades" <fletch@powerlink.co.nz>
To: "MX5List" <mx5list@mx5club.org.nz>
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It is quite conceivable that you've been running 14 degrees on 91 with no
knock/ping...

But some cars, due to manufacturing tolerances cant, and will need 96 to run
14... its a suck it and see situation... Sometimes, time of year comes
into it... a borderline car will run 91 in winter with cold air-temps, but
as it warms up, need 96 to avoid knock...

Most cars will need 96 to run 18 degrees, and its a good safety measure to
just tell every one to run it...

The reason for the different octane recommendations for US and Europe is not
because the cars are different, but because the Octane numbers are derived
in a different way, so the same fuel will have a different number...

Europe, Australia, NZ, and most of the world as far as I'm aware, reports
RON (research octane number) on the fuel you can buy. USA reports "pump
octane" or "(R+M)/2" , it is the average value of the RON and MON (motoring
octane number) for that fuel... MON is typically lower than RON, so for a
given fuel the (R+M)/2 will be lower than the RON.

We have 91,96, and now, in a few selected places, 98. In the USA 87-89 is
low octane, 90-92 are mid-grade, and 93-94 are high-test... Its my own
speculation (but I have no data or other evidence) that these fuels are
essentially the same as the ones we get... its just the "name" thats
different. Even if they are not the exact same formulations we get, they
will be much closer than the octane numbers on the pumps suggest...

Fletch.
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