Quote:
Originally Posted by Snaps
Reading up again, seems it's like this:
- vvti - variable cam gear timing (like adjustable cam gears, changes duration but not lift...?)
- vtec - variable cam lobes (two sets of lobes, changes between them to change lift + duration)
- vvtl-i - variable cam timing, with variable cam lobes like vtec (changes between two sets of lobes, while at the same time adjusts the cam gear timing for a fine tune)
- i-vtec - same as vvtl-i (uses two sets of cam lobes to change lift and duration, with electronically controlled cam gear to fine tune)
At least that's what I can manage to pull from the information I've found.
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It doesn't change duration, that's in the grind of the cam profile (in regular VTEC the description is correct, though). How the timing affects overlap or lobe separation angles are probably better description of what changes. But yes it's like an adjustable cam gear continuously and infinitely controlled while the engine runs, by the ECU, to the range limit of the pulley (for example it may have 15 degrees of adjustment range, but it can be anywhere within the range).