Only one change at a time, and dyno it. That's the only way to test. The scientific method!
I was just mentioning other things that I have tried. As far as engine masters goes, there are not any two identical engines in there enough to draw any conclusions from.
Different clearances, oils, oil wright's, additives, types of hones, deck clearances, polished or coated chambers, pistons' deck clearances, rotating and reciprocating weights, ignition, carb tuning, manifold and head mods, ring gaps, types, ring loading, valve seat angles, width, windage issues, port shapes and finishes, cylinder to crank centering/offset (very popular with 2 stroke engines), piston pin offset, port flow, tumble, and swirl, valve front and back cuts, valvetrain and valve weights, valvetrain rigidity, cylinder wall ridgity, blocks iron alloy composition, spring pressure, type of spring and material, oil pump volume, flowed oiling system, head temp, intake temp, spark plug gap, type of gap, protrusion, spark shrouding, spark duration, flame propagation, valve shrouding, cam lift, duration, ramp shapes and rates, type of cam, type of lifters, type and size of headers, same with collectors, fastener torque, deck plate hone types, and more, but my fingers are tired....
Bottom line, you can't draw any conclusions on any of these, and more variables, unless only one change is done at the same time to the same engine, by the same person. Period.
TIMINATOR
