|
Okay to clear up the name confusion:
Most variable valve timing systems are cam phasing. This means there is a fixed cam lobe, and then something that changes its relative position to the crank or whatever you want to use as the reference point. Almost every car has this on both exhaust and intake nowadays. If it's just called "variable valve timing" this is what they're talking about, and despite manufacturers sometimes making a big deal out of it, it is quite primitive and standard.
Then there are the variable lift systems. The most well known is VTEC, you have multiple cam lobes that are switched between essentially. Often time comes with phasing as well. Subaru AVLS is another, VVTL-i is another. If it's called "lift" then this is what it does.
The most sophisticated systems on the mass market are the continuously variable lift systems, and these are Valvematic, Valvetronic, and VVEL. The effect is like moving the cam away from the valve actuator to reduce lift and duration together (but they use intermediate rockers or something like that, depending on design). In the US only non-M (except the 1 series M and the recent models with turbo engines) BMWs after a certain point (N54 engines were not Valvetronic and were used up till the late 2000s) and Nissan G37s (and a few more models that I don't know off the top of my head) have this.
|