Quote:Tests on a Dyno would be interesting so as to quash the theory over reality situation.
I don't think we are talking simply theory, as it's not theory that 98RON has the the same energy as 92RON it's fact. And so on.
As to a bike going on a dyno, first with 95RON, then 98RON, here's my guess. It's gonna be hard to measure the difference, any differences would probably fall into differences in the region of dyno tolerances and uncertainties, ie the accuracy of the dyno and those little things you just can't get exactly the same between two tests.
But what we can be sure of is, if you keep putting higher and higher octane fuel in, eventually you'll get a fall off in performance as your ignition timing falls further and further away from it's optimum.
Quote:I had a Mitsubishi Lancer 1990 1.5 Carb and Shell V Power 98RON was without any doubt producing better power and far better fuel economy over 95 & 92RON.
I'm afraid a quick google ain't telling we what this was set up for, ie what fuel it should be run on. But 1990 is right in that transition period when Europe was phasing out lead. What does lead do, it's raises the octane rating and lubricates the valve seats, it's perfect apart from one little detail that it's highly poisonous. Now most cars back then ran on 4 star, so that translated into super unleaded. Also back then a lot of cars you still set up the timing by loosening the distributor and using a strobe (on was it no.1 piston spark lead) to point at the crank at a given rpm (tick over or 1000rpm) and you gently moved the distributor until you had the two little marks perfectly lined up.
So if your car still had this 1980's style set up, well you could do calculations, and advance or retard the ignition as required in order to try your motor on different fuels.
Of course using names rather than numbers confused some folks. I ended up buying a car that need 4star, the previous owner has done a couple of thousand miles on unleaded but said it was crap on it. I bought, then a few weeks later got it checked out as though the timing was spot on for 4 star, it just wasn't going as it should. The inlet valves were burn't. Conclusion, previous owner got his calculations wrong.
Anyway, that brings me to another wee point. I got a quote for getting it fixed. I then popped into Halfords and bought a Haynes manual and got the head off. Spent a bit of time and got the new inlets seated and put it all back together. One thing I didn't do was decoke the head. Even back in 1990 de-coke sessions were history. You can't get cleaner than clean!