91 Octaine in 4KSCQ?!

[Phil Payne]

> What used to be posted on the pump was R+M/2.  Or, the average of research
> (R) and motor (M) ratings.  Is that now called Pump Octane Number (PON)?

I've never heard of PON.

> To add a bit of background, research  octane ratings are higher because
> they're derived from laboratory tests, under ideal and controlled
> circumstances.  Motor numbers are lower, because they are determined under
> real-world conditions.

RON and MON are actually determined using the same equipment in the same laboratories - the
difference is that RON is measured on free-running apparatus and MON is measured with a load
on the test engine.  Clever things, with variable compression.  There's copious literature on
the internet, including a very good writeup on an Oxford University site.

-- 
  Phil Payne
  http://www.isham-research.com
  +44 7785 302 803