Well, I'm going to go against the grain here and state that despite much trying and some dyno testing, I cannot tell the difference.
Each engine will be set up to run on a certain octane of fuel. In the case of Omega B, that's 95RON. Feeding that same engine with 98RON or higher makes no difference except in very extreme circumstances.
sorry
I'd have to agree. Whilst the engine does have knock sensors and the ability to trim timing, I've never seen knock retard active on a non-faulty engine, regardless of fuel, and when it does kick in, it's a limp-home strategy that kills the performance in the event that it finds itself running on weasel-pee. The engine is simply not highly strung enough to suffer any issues on the 95 RON petrol for which it was designed, so it runs with exactly the same ignition advance on that as it does on any high octane petrol. You're never going to get a
significant change in performance in that scenario.
My westfield, on the other hand, with 11.5:1 compression and no knock control, really doesn't appreciate 95 RON. (and some petrol
marketed as "high octane fuel", for that matter!). So, it does make a difference to the right engine but you need high compression or forced induction, otherwise it's probably a waste of money.