yeah, I'm 99% sure I don't agree with any of that. vvt ls and non vvt ls both have no egr valve. egr was removed from the ls engine when the ecm got good enough to make them pass the epa limits without egr valves. somewhere around 2001-2003 I believe, depending on the car and long before vvt. there's not really a way to run exhaust back into the intake manifold using the cam. especially a single cam in block push rod engine just by advanceing and retarding the cam. this is been used for 50 years manually to move power band around. that's all it is.
as for afm, you're forgetting that both valves are left closed when 4 cyl is active. which means there's no air pulled into the cyl. so nothing to compress. you don't have pumping losses on those 4 cyl. so you're not only saving fuel burn from closed injectors, you're saving the tq needed to compress air/fuel. it 100% makes a difference but do the benefit out weight the down side of it breaking. not at all. it's junk because it fails. it would be just fine if worked for 300k without fail.
as for aftermarket vvt cams. this has also 100% been done. tx speed has spent a lot of time developing cams and they will supply a vvt tune for it. the 5 or 6th Gen camaros have vvt in the automatic cars and non vvt on the manuals. they get like 15ft lb of tq better with a correctly tuned vvt aftermarket cam. and it does show up on dynos and track. the liming factory is again the single cam in block. you gotta limit the amount of movement to such a small amount the bigger the cam gets so the valves don't hit the pistons., it almost isn't worth it. now a double over head cam with control of both individually. 100% worth it.
as for afm, you're forgetting that both valves are left closed when 4 cyl is active. which means there's no air pulled into the cyl. so nothing to compress. you don't have pumping losses on those 4 cyl. so you're not only saving fuel burn from closed injectors, you're saving the tq needed to compress air/fuel. it 100% makes a difference but do the benefit out weight the down side of it breaking. not at all. it's junk because it fails. it would be just fine if worked for 300k without fail.
as for aftermarket vvt cams. this has also 100% been done. tx speed has spent a lot of time developing cams and they will supply a vvt tune for it. the 5 or 6th Gen camaros have vvt in the automatic cars and non vvt on the manuals. they get like 15ft lb of tq better with a correctly tuned vvt aftermarket cam. and it does show up on dynos and track. the liming factory is again the single cam in block. you gotta limit the amount of movement to such a small amount the bigger the cam gets so the valves don't hit the pistons., it almost isn't worth it. now a double over head cam with control of both individually. 100% worth it.
