> Larry Baltz Wrote:
> I saw that article too, Ken. My point being without the engine
> characteristics that make higher octane gas necessary (high intake
> pressures, high compression ratios, advanced timing), high octane gas is
> likely not being fully consumed because of it's slower combustion rate.
this may be part of the key...
what evidence do we have that higher octane gas necessarily has a slower flame front speed?
my experience and reading of the available data sheets has shown me that those two metrics are not directly (inversely) related. unfortunately flame propagation speed measurements/ratings are not easy to come by which make it difficult to spot trends. it takes some digging to get those burn rate numbers...
I find the wiki statement regarding specific gravity vs. octane to be a bit suspicious as it is uncited. i remember going over a similar discussion a few years ago in a different forum during which i stumbled across https://www.vpracingfuels.com/master-fuel-table/ which shows multiple examples of fuels with higher octane AND higher SG, and vice versa. while the two metrics may often be observed as inversely correlated there are exceptions which would indicate they are not causally related, as can be seen after a few minutes reviewing VP's matrix.
i've seen it bandied about for decades that higher octane means less energy, and higher octane means slower flame, and i've just not seen the data to back that up. while in some fuels that may be the case, in others it is not. however, i do agree that running higher octane than is necessary to prevent detonation is a foolish way to spend (waste) money!