Quote:
Originally Posted by Snaps
vvt-i used to only control the intake cam, because it generally made very little difference when added to the exhaust cam (I believe as exhaust valves/ports are generally larger anyway). Maybe they've found a way for it to make a larger difference, which is why they'll be adding vvti to the exhaust cam on the FT86 too?
From what I've made sense of, vtec uses a camshaft with two different lobe sets for each cylinder, and the used lobe set is changed at a certain rpm, where vvt-i uses a camshaft with a single lobe set for each cylinder, but instead uses a variable gear to change the gearing on the camshaft to essentially lengthen the timing, allowing more flow.
That's only if I've got the concept right though.  |
VVTL-i is closer to Honda's iVTEC not the old VTEC due to the cam phasing (old VTEC was just lift/profile changing). I think the newer Toyotas are VVT-i on both intake and exhaust (
Intake valves are typically larger than exhaust valves) but there is something called 'Valvematic' I think it is, that is Toyota's next-gen cam/valve control tech.
I haven't really heard of VVTL-i in anything other than the 2ZZGE. Can anyone clarify for me?
The Lexus LFA I believe only used VVT-i on intake and exhaust.