Quote:
Originally Posted by Ecky
Variable valve timing is automatic and, generally speaking, improves the efficiency and/or power generation over a broader RPM and load range. It's not something for a driver to take advantage of.
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I remember on my Civic hearing about a VTEC "switchover" point--turns out Honda uses extra cam lobes and rocker arms that lock at a certain RPM (or do/did on SOHC engines, at least). Toyota's VVT-i, on the other hand, seems to advance timing by adjusting the camshaft drive of the intake cam. I'm guessing there's no set RPM/load where that happens, but probably a variety of conditions under which it does. So, on a Honda you can stay out of VTEC if you want, but on a Toyota you can't stay out of VVT-i?