Yes you are right I expressed myself wrongly, the angular velocity is due to the rotation speed of the crankshaft, determining advance; The piston velocity is linear.
What I wanted to say is that electronic ignition varying "timing" could allow much more latitude in terms of fuels that could be used, as it seems there is no additive which is likely to slow down the propagation of combustion process of burning gasoline to replace tethraetyl lead.