VTEC...MIVEC....VANOS

okay....we have heard that VTEC is so powerful....actually VTEC...mivec...vanos...VVT all using the same principal, which will be explained later on.

BUt forst of all, let's see what does abbreviation VTEC stands for.VTEC- variable valve timing and lift electronicl control.

on your left, i have put up a picture of 2.0 V6 MIVEC which id currently being used in Mitsubishi FTO.

The basic mechanism used by the VTEC technology is a simple hydraulically actuated pin. This pin is hydraulically pushed horizontally to link up adjacent rocker arms. A spring mechanism is used to return the pin back to its original position.
  The VTEC mechanism is covered in great detail elsewhere so it is redundant to go through the entire mechanism here. Ok, lemme start by explaining the basic operation of  VTEC engine. Before that, check out the cross sectional diagramof a vtec engine first

VTEC comprises of a camshaft with two cam lobes side by side. These lobes drives two side by side valve rocker arms. The two cam/rocker pairs operates independently of each other.One of the two cam lobes are intentionally drawn to be different. The one on the left has wilder profile, it will open its valve earlier, open it more,and close it later, compared to the one on the right. Under nornal operation, each pair of cam lobe/rocker arm assembly will work indepently of each other.
  VTEC uses the pin actuation meachnism to link the mild cam rocker arm to the wild cam rocker arm. This effectively makes the 2 rocker arms operate as one. This composite rocker arm(s) now clearly follows the wild cam profile of the left rocker arm.