Originally posted by perry:
VCT = variable cam timing.. Sorta like VTEC I guess. But on the Contour, it's not used to make power, and it's only on the exhaust cam.
Yep. VTEC uses hydraulic pressure to move a pin in between sets of rocker arms, thus activating or deactivating them. For VTEC to work, the cam must have multiple lobes to switch between for each cylinder. This changes cam timing and lift, and in some cases in-cylinder swirl.
VCT only changes cam timing by using hydraulic pressure to rotationally index the camshaft. On the ZETEC, it is only exhaust VCT which improves NOx emissions (like an EGR valve does) and has a small impact on fuel economy.
The SVT Focus has intake VCT which allows for more power and also allows for lower NOx.