Okay.. I understand now. (Someone had explained to me about pitch speed in the past but I don't recall getting into the thrust vs. speed correlation at that time) With all of this understood, getting an engine to perform better on the higher pitch prop would mean increasing its performance or its ability to do work. If a given engine has a given ability to do work (stock), increasing its ability to breathe would increase its ability to do work (changing port timing). What I'm trying to understand is what changes would need to be made in what areas to increase its power output. There is a long debate of modifying engines, mainly in the car engine realm. I have seen dyno graphs of two identical engines make totally different power curves (and higher power output) - modified vs. stock form. I know that many budget engines are ported conservatively for user-friendliness and fuel economy, but I know its possible to make port modifications to increase performance. I guess what I'm trying to learn is, what effect on performance would (I'm just using examples here) opening the exhaust sooner or opening the crankshaft port sooner or keeping it open longer.

It is assumed that Nitro content is maxed to what the engine can handle, and the given RPM ability is within the limits of the props being used. Also, to keep it simple I'm going to say a full-wave tuned pipe isn't an option.