VVT point in 20v Silvertop

quicklvn · Post by **quicklvn** » Fri Sep 22, 2006 8:20 am

Hey, Iv'e done a search for this but couldn't find any posts that really answered my question.

Im sure this is really well known but i've only had the car a little while and don't know much about the VVT (more into turbos).

Its a 20v Silvertop in an AE101 levin, I think the VVT seems to come a bit early (about 3,500rpm) and i'm not convinced this is the right point. So im afraid im losing power.

What is the correct rpm for it to kick in and do you need a controller to adjust it?

NZ_AE86 · Post by **NZ_AE86** » Fri Sep 22, 2006 8:40 am

Not 100% sure but I think it is 3200 or 3500. Someone else may be able to confirm?

Post by **Mr Revhead** » Fri Sep 22, 2006 9:03 am

its not RPM switched
once the engine is half warm, anything over 1/4 throttle switchs it.
its very hard to drive it with out activating it

slighty_sykotic · Post by **slighty_sykotic** » Fri Sep 22, 2006 12:38 pm

On my preface lift (1991) ae101, it was more than half throttle - 3/4 throttle activated it. (I had a very bright VVT light, so I know when it activacted.

Revhead, is the 20v you are talking about facelift or pre facelift?

(wondering if it's different as I used to find it very easy to drive without going on cam).

--Sykotic

Post by **Mr Revhead** » Fri Sep 22, 2006 12:41 pm

ah yes... my levin is preface lift... however the ecu part number was facelift. forgot that.
so yeah as i said above for facelift. havnt personally tested preface lift.

sergei · Post by **sergei** » Fri Sep 22, 2006 1:41 pm

The amount of throttle needed to activate the VVT varies (lineary dependant of RPM) it is the same for both pre-facelift and post face lift silvertop and very similar in blacktops (although switch off point is lower ~ 6800 vs 7200).
To activate VVT on lower RPM it is required less thottle than on higher RPM.

$CENSLS1$ · Post by **$CENSLS1$** » Fri Sep 22, 2006 2:20 pm

sergei wrote:The amount of throttle needed to activate the VVT varies (lineary dependant of RPM) it is the same for both pre-facelift and post face lift silvertop and very similar in blacktops (although switch off point is lower ~ 6800 vs 7200).
To activate VVT on lower RPM it is required less thottle than on higher RPM.

Aaahaaa, sounds like it could be quite a complicated system...Especially if you were to have problems with it...

quicklvn · Post by **quicklvn** » Fri Sep 22, 2006 2:38 pm

Cool thanks for the comments guys.

So do you think its worth getting a controller and messing with it? (I've heard some vtec controllers work on these). I'm getting sick of the lack of power at high revs.

sergei · Post by **sergei** » Fri Sep 22, 2006 2:49 pm

NOPE. VTEC controller is just an RPM switch, the stock system is far better option. You don't need to mess with it unless you have aftermarket cams., but then it becomes a head ache.
The system itself is very simple - 1 solenoid, 1 hydrolic pulley thing, 1 2d maped output.

HELBND · Post by **HELBND** » Fri Sep 22, 2006 2:50 pm

lack of power at high revs? my silvertop always felt like it wanted to keep pulling beyond the rev limit

Post by **Mr Revhead** » Fri Sep 22, 2006 3:20 pm

yeah as sergi said
unless you have mods to suit and a proper ecu leave it alone

maybe you have a fault?

what do you mean by lack of power at revs? what revs?

quicklvn · Post by **quicklvn** » Fri Sep 22, 2006 4:37 pm

It's just the pull kind of fades out towards 6,500rpm and it just feels to me like its revving with not added power (i've heard this is just the way they are). It's still pulls hard it just doesn't pull harder at higher revs so I wanted to alter it a bit.

Post by **Mr Revhead** » Fri Sep 22, 2006 5:11 pm

easy
link ecu and cams

the torque peak on these is around 5500-6ish tails off after that.
so change gear. 8000 is just a waste

quicklvn · Post by **quicklvn** » Fri Sep 22, 2006 5:19 pm

Yeh thats what I thought when I was dragging last time.

I might try changing earlier on my next trip to meremere.

AceSniper · Post by **AceSniper** » Fri Sep 22, 2006 6:08 pm

check other things like timming and so-on
iv noticed some 20v's just die getting into the revs were some just keep going

Post by **Mr Revhead** » Fri Sep 22, 2006 8:19 pm

fuel type? ignition timing?

GorGasm · Post by **GorGasm** » Fri Sep 22, 2006 9:24 pm

Sounds a bit like people are confusing VVT as a Vtec equivalent.

VVT aims to change the time that valves open. You would want to do this constantly to get the optimum timing at each rpm and load, hence why you dont have a switch point for it because its always working.

Vtec/VVTL/VVL/mivec or similar with lift variation is different.
These systems alter the amount of time (duration) that the valves are open for. In the case of Vtec two cam profiles are incorperated into the engine, neccessitating the need to have a switch point to change cam profiles as the performance cam does not work very well for low rpm. These systems can have switch points as they are on/off type technologies.

Therefore 20v engines dont need a switch for the VVT as youll only make performance worse and because vtec and etc have variable lift and duration they make more power.

NILPSI · Post by **NILPSI** » Fri Sep 22, 2006 11:56 pm

I have a small picture that may help explain vvt a bit better

It shows where the vvt switches on and off on a revs vs. throttle potition graph

I TRD I · Post by **I TRD I** » Sat Sep 23, 2006 2:43 am

VVT is either on (Cam angle 15 degrees advanced)or off (0 degrees) no in between .activation point on silver tops is determined by TPS and rpm above 3000 -3500 while black tops use TPS, rpm above 1700 and map. i know black tops deactivate at high rpm about 7000 not sure if silver tops do this tho
VVTi (not found on any 20v 4age's) is constantly variable and adjusts the cam angle anywhere from - 15 degrees thru +15 degrees changing to always provide optimum cam angle

VTEC controllers only have activation point switching not allowing deactivation at high rpm and since advanced cam angle is only effective in the mid rev range VTEC controllers dont make good VVT controllers

If your power feels like its dropping away at high rpm retarding ignition timing 2 degrees and see how it feels i find if i set my base timing to 8 degrees BTDC its sluggish at low rpm but at high rpm engine seems to accelerate more as rpm increases if i set ig timing to 12 BTDC its very responsive at low rpm but power drops away at high rpm .

Just try your ig timing in a couple of different places around 8 - 12 BTDC(always using correct adjustment procedure) and decide what is best for your driving style i love revving my black top all the way out and have found that 9 BTDC is good for me . Im running quad trumpets on port matched and polished thottle bodys, inlet manifold and head ive got no power below 4000rpm but after that its all worth it

AceSniper · Post by **AceSniper** » Sat Sep 23, 2006 3:37 am

silvertop and blacktop use the same switchng method aslong as your water temp is warm vvt will come on when the tps hits 30-50ish % (seams to very)
so yes its possable to have vvt come on when your foots to the floor in very low revs but since your not there long it goes un noticed.