Vvt i

[hiluxfan]

Hi there everyone.
I have been searching high and low for information on the Lexus VVT I but without much luck. The best I found so far is http://www.billzilla.org/vvtvtec.htm
Can any of you clever people please explain in more detail?

 

[sideshow]

all it is is full variable cam timing
early motors had on of type cam timing adjustment
vvti means full variable

 

[4U2QUIK]

here's the vvti wiki
http://en.wikipedia.org/wiki/VVT-i

 

[hiluxfan]

Vvt i ???

Thanks a lot for that info. Much appreciated.
Just a few questions specifically about the Lexus.
1. On which cam does the VVT I act? (Intake, exhaust or both)
2. Does the ecu control each bank individually? (I.e. two cam position sensors and two outputs)
3. Are there any aftermarket ecus that can do the job properly?
4. What is the displacement of the VVT I engines? (All 4300cc?)

 

[4U2QUIK]

http://en.wikipedia.org/wiki/Toyota_UZ_engine
there aren't any aftermarket pcm's that controll vvti as far as I know besides maybe possibly aem.

 

[XR8tt]

Motec ..
http://www.motec.com.au/m800/m800overview/

 

[JBrady]

Actually VVTi stands for Variable Valve Timing with intelligence.

Since this is predominantly a 1(2,3)UZ-FE forum you are likely referring to the 1998-2006 V8 engines which advances or retards the intake cam based on operating parameters. It is not an on/off feature and the positioning is a compromise. It is used as much for emission control as power and in fact makes the engines LESS smooth at idle compared to the earlier not equipped engines.

See the attached images showing the factory programming based on conditions. The exhaust cam is shown as a back arc and shows the opening point BBDC and closing ATDC. The intake position MOVES and with that its opening point BTDC-ATDC and closing ABDC.

At high speed high load the cam is retarded relative to low-medium speed and high load. Ideally/relatively you would want an earlier opening and later closing and this system cannot do both at the same time. The "Holy Grail" of VVT or VVA (variable valve activation) would adjust the intake and the exhaust duration and lift infinitely to optimize whatever demand is desired. The nicest compromise I have seen is by an individual inventor and his designs outlined at www.pattakon.com/pattakonFVVA.htm

.

 

[XR8tt]

In any case a GOOD tuner can get this simple VVT up and running with
one of it's auxiliary outputs...
It doesn't have to follow std computer settings to work...
Early VVT was quite simple, mainly working on inlet timing...

 

[sideshow]

u need a good aftermarket ecu and tuner
to tune vvti. which is harder to tuner than Vvt
vvti has extra cam sensors which tell it where the
cam is depending on the vvti solenoid
this signal is independent to the proper cam sensor
the vvti cam also be affected by oil pressure to
it's fiddly to tune so ask yr tuner first

 

[hiluxfan]

Vvt i ???

Hi Guys
Thank you for all the great info. Really appreciated.
I used to work in the racing industry and was employed by various manufacturers, including Toyota Motorsport.
I have a lot of experience with different engine management systems, so Ill be doing the tuning myself.
However when I “retired” BMW just launched their Vanos but we were not allowed to use it due to the rules of the series, so I have no experience with any kind of VVT system.
I guess it is not worth going with a VVT I engine if you cannot get the VVT I side of things to work properly. (I.e. correct ECU and tuning)

 

[XR8tt]

Well ??
Even if it opens up after peak torque to widen rpm torque ..
It will be better than non at all..
The program needs to prevent this I guess at high engine loads ??
Nothing a good tuner can do street tuning..
Yes they are alot more sophisticated now..

 

[cyberdiamond]

http://en.wikipedia.org/wiki/Toyota_UZ_engine
there aren't any aftermarket pcm's that controll vvti as far as I know besides maybe possibly aem.

ProEFI ecu can as well

 

[gloverman]

All The link ECU can do it. The stock car guys over here are using the VVti in the restricted 4 litre class running a carburator and a link lightening which is a ignition only ECU. The Extreme can also run the fly by wire throttle body. Link had a UZ motor as their test motor for vvti and the product has been avaliable for a few years now. Cheers

 

[cyberdiamond]

Yeah the proefi (that I use) also controls the DBW but it may be a bit overkill for some.

The Link (or Vipec) are great ecu's as well.

 

[XR8tt]

All The link ECU can do it. The stock car guys over here are using the VVti in the restricted 4 litre class running a carburator and a link lightening which is a ignition only ECU. The Extreme can also run the fly by wire throttle body. Link had a UZ motor as their test motor for vvti and the product has been avaliable for a few years now. Cheers

With 450+ h.p...

 

[hiluxfan]

Link

I just had a look at the Link website. The G4 Extreme looks like an awesome piece of kit! It should handle the VVT I very well. I’m currently waiting for a quotation from them.

 

[JustenGT8]

"To be or not to be" there's a quotation for you

Autronic SM4 and Haltech Platinum will also do VVTi control.....heaps of options really

 

[gloverman]

I have a early silver G4 extreme. Was one of the first ones released as I am also a link dealer. Doing a group buy for some customers so flick me an email to [email protected] and I will do you a price. Cheers

 

[sideshow]

I think the link/viper has best user friendly software
can't say much bout other brands which r fkt
won't name them

 

[hiluxfan]

Thanks Gloverman. PM sent