Sorry, but you'll have to explain how a change in *timing* will change the amount of fuel burned...
*How*? It will still ingest precisely the same amount of air, the carburetor or fuel injectors will deliver precisely the same amount of fuel and the fuel will still all burn.
It isn't? Then what is it? A timing change is one way of completely dealing with lower octane fuel.
Why? The intake tract doesn't know the fuel is lower octane, so the amount of air doesn't change. The carburetors-injectors don't know the fuel is lower octane, so the amount of fuel delivered doesn't change.
So how does just changing the timing make an engine burn *more* fuel?
If that is the case, why bother with higher octane fuels *at all*?
It burns more fuel, but not in straight proportionality to the lower energy density.
"otto cycle thermodynamics compression ratio efficiency"
Do the research.
-- Alan Baker Vancouver, British Columbia "If you raise the ceiling 4 feet, move the fireplace from that wall to that wall, you'll still only get the full stereophonic effect if you sit in the bottom of that cupboard."
