this is one aspect of what happens in the cylinder in regards to ignition timing being linked to CO production/flame kernal. Spark timing for power is generally the same at 8,000rpm as it is for 3,000rpm.This is because the flame speed increases at the same rate as the rpm.There is no real evidence as to why this occurs but most will say it is a engine phenomena.Bruce thought that there was a link between piston movement and the styles of fuels.Engines of the past employed totally different piston velocities to now because of the differences in fuel. He went on to say that it is possible that people stumble upon piston speeds and velocity profiles that produce best power in racing,when actually what they are doing is optimizing the burn speed to the piston speed. so if you do this successfully you dont need complex timing lines. Some engines need advancing as the rpm increases as it depends on the CO residual of the cylinder. I see a lot of engines with lots of CO residual and that needs a complex timing line,thats why im always spending time with timing just about more than the fueling when i tune.Ignition strength and advancing is terrible in most jobs i go to. What is wrong is that CO slows the reaction in the unpredictable ways and it slows the reaction differently from one reaction to the next. I make sure that when the plug engages more fuel molecules,the gassing of the fuel is improved first.