What does V-tec in honda's cars mean?

[Xulfiqar]

Some of the people above have given one of the most funny explanations that there possibly could be... lol!

The thing is that in an engine, pistons rotate the crankshaft, and then the crankshaft drives the timing chain(or pushrods) that in turn rotate the cams of the engine. Its a mechanical system linked to each other and hence the opening and closing timing of valves is determined as per the gearing ratio of this system... In a normal engine its a fixed ratio (Turning of crankshaft, turns the cams at a particular speed)

However in a Toyota's VVTI or Honda's Vtec (mitsubishi and Nissan have similar systems with other names) the ratio is not fixed and can be changed... The valves can be opened/closed for optimum fuel economy or optimum power...

Hence in a Honda.. If u take it above a certain RPM, the engine changes the Valve timing to make the valves open and close at a more precise time and to ensure optimum power delivery. Hence you feel a kick down effect.. or a certain change in acceleration and engine sound

toita vvt is not the same, it can range from just changing phase of the cam to actually changing valve lift (2ZZ-GE etc). the cam phaser change is the most common on econo engines, its the little "cherry blossom ki dibbi" in place of the regular camshaft gear on new engines.