Ignition advance
 

How does higher octaine fuel effect ignition advance?

Higher octane fuel allows for more advanced ignition...more power ;-)
The chemical make-up is generally stronger and requires more energy to break them down so are less prone to knock.
It sort of takes longer to completely combust (in effect!)

Any idea what I sould be seeing - with a couple of tanks of 98 ron it seems to have gone from 27' to 30' but that may just be because I've only just started watching it.

Na sounds about right mate :-) my zed used to do the same at similar sort of figures. V6 ecu must spot the change through oxygen sensor i guess....

i thought it was the 2 knock sensors, one on each bank in the V that would allow the advance/retard of ignition?

Could be mate.... I know my omex just uses the knock sensor as a "fault finder" as apposed to a tuning aid..Hmmm

The S2000 ecu monitors the sound of the combustion process with the knock sensors and alters the ignition advance accordingly keeping the timing right on the point of detination. Over a few hundred miles of running a higher octaine fuel it alters the fueling and ignition so should run a bit better!! If you put a lower octaine fuel after it's adapted to a higher octaine it will adapt back!!

I ran 98 ron for 6 months and noticed no difference except higher fuel consumption.

That is often the case!! My 180 runs just a bit smoother and is a bit more responsive on V Power. Power and economy are much the same!! The engine was designed and mapped to run well on 91 octaine then the adaptive fueling/ignition was added to account for engine production tolerances and engine were. So by switching to 98 won't guarantee an instant power or economy boost :(