"The alcohol plot is quite mis-leaning if it was described in text only. The engione virtually runs on alcohol rather than gasoline. The experiment is probably done on 2-valve per cylinder, long stroke enigne - octane demand/performace is that much greater is BMEP is "detonation threshold limited". However, it give a good indication of fuel quality against power. "
I don't believe that is entirely true. Remember that the alcohol/water is injected at a fixed percentage relative to the fuel. If the fuel is leaned, so too is the alcohol. At a 22:1 A/F ratio, which is at the far left of the alcohol plot, the alcohol included A/F ratio is still only 16.5, and if you take into account the fact that alcohol is stoichiometric at less than half the A/F ratio gasoline is, it's realistically going to act like a 19:1 A/F ratio.
The engine in this experiment was running on AN-F-28 aviation fuel. The relative octane enhancement of the Methanol would depend on the octane of that fuel.
But whatever "octane enhancement" the Methanol provides should be constant across the air-fuel ratios. It would not enhance disproportionately more in the lean regions.
Adrian~
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