well for starters the pistons are concave and there is almost no combustion chamber...that combined with the use of only 12 valves (1 intake and 2 exhaust) at low rpms creates a swirling effect that allows the engine to run with more air and less fuel...but at higher rpms this effect is mroe harm than good so the other intake valve opens and you left with somthing similar to a sohc 16v non vtec engine....anything else?