VVT vs VVT-i

[BZG Wagon]

VVT vs VVT-i - Whats the difference?

From what I have gathered, VVT comes on at a predetermined rate and VVT-i come in based on throttle position.

Which one is better / more power? Pro's Con's of each? Is there much difference?

[matt dunn]

VVT vs VVT-i - Whats the difference?

From what I have gathered, VVT comes on at a predetermined rate and VVT-i come in based on throttle position.

Which one is better / more power? Pro's Con's of each? Is there much difference?

Here's what i believe it is.

VVT is variable valve timing
and
VVT-i is variable valve timing with intelligence

The difference is that VVT is either on or off. Like the 20V's the cam is either normal position or 30 deg advance. What switches it has no dteermination of what it is called.

VVT-i is infinatley variable and can self adjust to anywhere in the adjustment range. ie it can be normal, 30 deg advance or anywhere inbetween like 15deg advance for example.

There seems to be great debate about what switches when but i dont think it matter in relation to weather it's vvt or vvt-i.

I may be wrong but thats how I understand it.

Matt

[Mr Revhead]

yeah thats what i reckon
vvt has 2 postitions, once certain parameters are met (temp etc) it allows the cam timing to change at a bout 4500rpm

wth vvt-i (i does=intellegence) its more flexible and uses more inputs i beleive

[nobody]

These two links have some good info:

http://www.billzilla.org/vvtvtec.htm

Excerpt:

VVT-i - where instead of the simple 'on' or 'off' positions of the earlier VVT system, this version can make the inlet cam retard/advance to any angle between the maximum limits, and to do this the camshaft has a position sensor on the back of the head.


http://www.puresportscar.com/FAQ/vvtli.php

Excerpt:

VVT-i continuously varies intake valve timing throughout the rev range by hydraulically rotating the camshaft relative to its drive gear.

VVT does not do this continuously.

[CozmoNz]

so at full throttle, they are equal!

its just vvt-i helps with slightly more omph at 50% throttle etc, because it will advance by 15 degrees and be better on fuel.

add lift and you have GODLY power ;D

[matt dunn]

so at full throttle, they are equal!

at some point in the rev range yes,

but at full throttle VVT-i will vary with revs to maintain max power throughout. It's not alway max advance = max power.

[strap-on]

from my observations on my silvertop, vvt doesnt open at all untill u hit full thottle

thats what always seems to happen

damn i need me a blacktop

[AceSniper]

vvt on a silvertop should come on anywere around mid throttle.... its not always in the same spot. same as a blacktop.

[CozmoNz]

so at full throttle, they are equal!

at some point in the rev range yes,

but at full throttle VVT-i will vary with revs to maintain max power throughout. It's not alway max advance = max power.

that is true....

anyway to get a controller that can switch you from vvt to vvt-i?

[10k 20v]

ok, the vvt (silvertop) system is only activated when the engine is up to operating temp (around 50-60 degrees c) then is thottle dependant and rpm.
Dow low - 1000-2000 rpm it only takes around a 10-15% throttle opening to activate vvt but will deactivate much past that rpm untill you increase the throttle opening. then around the 5000rpm region you need 50% throttle opening to activate the vvt. then at 7000rpm the system deactivates regardless of throttle position (although on most ae101 stock tacho's they dislay 7400).

I've never had the opertunity to map the blacktop so i'm not qualifed to comment so therefor i say nothing

[matt dunn]

anyway to get a controller that can switch you from vvt to vvt-i?

no. the head is not capable of it no matter what controller you use.

[CozmoNz]

Ok, so what excactly does a controller do then?

[Zak]

I think the controler just lets you decide when the VVT kicks in, but not how much, as it's either on or off.

[Disco]

Matt Dunn is closest so far with vvt being either 15deg advance on spark and 15deg on intake cam (so 30deg) and vvt-i figures out how much advance is best and uses that, makes for a much smoother operation and you don't really notice it. (it's not like in the silvertop where when it comes on it's like you've just flicked on a supercharger.

I am under the impression that VVT is operated by a combination of Throttle Position, RPM and Oil Pressure. So it's load based. (which is interesting because that would mean if you wanted to install an electric oil pressure guage there should already be a feed to the ECU but i'm not sure that there is so this could be wrong.)

To prove this, install a VVT light and next time you're out cruisin the block poppin' collars and flickin' dollars, pickin up ho's in your 20v and you come to a hill...

...Keep the throttle sitting just before where vvt would come on (so it's still off when you hit the bottom of the hill) and then watch it come on as the load increases.

I drive a facelift silvertop which is slightly different from the non-facelifts so the VVT op maybe different as well.

[ants_ae92]

There are 2 types of silvertop 20v. The early model - Same switching point. And a later one. I think the early is pre may 1993 or something like that.

The later one you guys are describing is load based. Or whatever.

read this on bill sherwoods site. Whether its true, who knows.

[AceSniper]

There are 2 types of silvertop 20v. The early model - Same switching point. And a later one. I think the early is pre may 1993 or something like that.

The later one you guys are describing is load based. Or whatever.

read this on bill sherwoods site. Whether its true, who knows.

Iv run both facelift an pre-facelift silvertop ECU's an on both they turned on VVT under load/throttle (vvt light)

[CozmoNz]

and blacktop is the better version of them both!, muwhahaha

yeh.. um... yah

[vvega]

blacktop has slightly diffrent cam advance retard

v

[10k 20v]

Silvertops load dependant. it doesn't just come on as you go up the rev range

[BZG Wagon]

How do I install a VVT light?