I posted this in the other video's thread but think it's worth it's own topic, purely because the amount of ground it covers. Some of you may have read vizards book, whilst this concerns the A series engine, it references topics we regularly discuss in the modified engine section up to and including. He generally explains things pretty simply, and if you want to understand a bit more about a number of topics including those below, watch it.
Filtration
Fuel atomisation
Compression ratios
Dynamic compression ratios
Brake Specific fuel consumption
Porting
Valve design
Valve seat design including 3 angle
valve modification
Lifter / bucket diameter
Roller rocker design and limitations
Ramp angles on camshafts
Cam shaft timing
Carbs vs injection (lucas mechanical)
Valve shrouding
Bigger vs more valves
Decking blocks
Squish height
Burn time
Rod lengh / ratio
Octane ratings
Water injection
and some more that i can't remember
Cheers
J