vvtl-i?

[laz_10]

i never really understood what vvtl-i did. can anyone please tell me? what does vvt do? the lift? and the i?

[SilverRide]

V V T = variable vave timing

L = "Lift" : a second set of valve cams kick in at a certain RPM to provide more "lift" to cam followers

I = intellegence: this is merly a marketing desination refering to computer controled ignition and V V T.

[laz_10]

i know what vvt stands for. what it does is what i dont understand. its like vtec? right? does it make the engine more responsive during hard driving?

[chameleon]

Basically what VVT does for you is allow you to get the full potential of the engine at all times, ie. more power and better fuel economy. This is accomplished by the ability of the cars computer to make adjustments to the valve timeing as you drive.

Back in the olden days, the way to adjust the timing of the car was to pop the hood and rotate the distributer clockwise/counterclockwise to advance/retard the timing. When you advance the timing you would get a little more power at the expense of a little fuel economy, so enthusiasts who were interested in performance would adjust the timing so it was advanced more than it was stock.

Our cars with the VVT technology have a huge advantage over this old method of timing adjustment because the computer can continuously make adjustments to the timing as you drive. This allows the car to run at a much higher timing advance than would ever be possable on a non VVT car. This is because if a non VVT car was set to achive maximum power, the engine would knock at high rpm's or when it was under load. On our cars, if you are going up a hill(example of engine under load) the computer will just retard the timing a little so the engine will still run fine, and when you reach the top of the hill, it will advance it again.

The lift is basically like VTEC, it allows you to have two completely different camshaft profiles on one single camshaft. If you have a camshaft that is designed to make power at a really high rpm's the car will be super slow at low rpm's. If you have a camshaft that is designed to make power at low rpm's, it will be worthless at high rpm's. This is where the "i" in VVTLi comes in. It is a second set of lobes on the camshaft that kick in at high rpms to open the valves up more and allow more air to enter the engine, which of course means more power. This allows the Celica to have a fuel efficient camshaft that makes power at normal rpm levels, and a seperate high rpm race car like camshaft that starts making power super high to take over when the first camshaft profile cant provide any more power.

So what all that means to the driver is that your car gets great gas mileage, is really responsive, and makes power over a huge rpm range(idle to 7,600rpm), all thanks to VVTLi.

[laz_10]

damn thanx! that clarified everything.

[chameleon]

;)

[ludatic]

toyota's version of vtec

[ludatic]

although toyota's has "intelligence"... but what i don't get is.. ur lift always kicks in like at 6000rpm, it's at a set point.. but there's "intelligence"..

on honda's i-vtec engines.. vtec'll kick in a lil bit earlier than normal when its needed.. it never kicks in at the same time.. where vtec is at a set point.. someone correct me if i'm wrong

[RiCeY GtS]

ur wrong ;)

[ludatic]

Originally posted by RiCeY GtS
ur wrong ;)

haha u homo, gimme an explanation of the difference between vvtli, vtec, and i-vtec.

[chameleon]

Originally posted by ludatic


haha u homo, gimme an explanation of the difference between vvtli, vtec, and i-vtec.

vvtli was a technological advancement over vtec. The intelligence of the vvtli system has nothing to do with the second camshaft profile/lift, it only concerns itself with the variable valve timing abilities of the car. Basically, the intelligence of the vvtli system allows the cars computer to monitor driving condition variables and make timing corrections. Toyota's vvtli systems ability to constantly monitor the needs of the engine and make timing adjustments as you drive is what makes it better than vtec. vtec has a degree variable timing, but it is only adjusted based on a pre-set fixed curve, not based on the actual demands of the engine at any given time, which is what vvtli is capable of.

i-vtec is Honda's response to vvtli. It is technologically more advanced than vvtli and currently has an advantage over it. You noted the advantages that i-vtec has over vvtli in your previous post. So right now, i-vtec is the most technologically advanced engine management system in the Japanese sport compact scene. But just as Honda made it's effort to top vvtli technology, another company will undoubtedly make an advancement over i-vtec in the near future. Increased competition in the market place will demand it.

[ludatic]

Originally posted by chameleon


vvtli was a technological advancement over vtec. The intelligence of the vvtli system has nothing to do with the second camshaft profile/lift, it only concerns itself with the variable valve timing abilities of the car. Basically, the intelligence of the vvtli system allows the cars computer to monitor driving condition variables and make timing corrections. Toyota's vvtli systems ability to constantly monitor the needs of the engine and make timing adjustments as you drive is what makes it better than vtec. vtec has a degree variable timing, but it is only adjusted based on a pre-set fixed curve, not based on the actual demands of the engine at any given time, which is what vvtli is capable of.

i-vtec is Honda's response to vvtli. It is technologically more advanced than vvtli and currently has an advantage over it. You noted the advantages that i-vtec has over vvtli in your previous post. So right now, i-vtec is the most technologically advanced engine management system in the Japanese sport compact scene. But just as Honda made it's effort to top vvtli technology, another company will undoubtedly make an advancement over i-vtec in the near future. Increased competition in the market place will demand it.

oh alrite... too bad... all this vtec/vvtli/ivtec stuff is still weaksauce compared to the turbos they had in supras..

[chameleon]

Yes, but part of what made the last generation of supra soo great was the implimentation of vvti technology on the engine. The supra was one of the first Toyota cars to ever have it, it was used on supra's way before they put it on Celica's. The good thing about it is that your car will always make it's own adjustments to make the most out of any modifications that you do to it. Probably part of the reason why Celica guys can slap an intake and an exaust on thier car and go from a 15 sec 1/4 mile to a 14.4 sec 1/4 mile, or put a 50 shot of NOS on thier car and get into the mid 13 sec. range. Well, that and the high compression, but the vvti technology is a really good thing to have on your car. :)

[ludatic]

Originally posted by chameleon
Yes, but part of what made the last generation of supra soo great was the implimentation of vvti technology on the engine. The supra was one of the first Toyota cars to ever have it, it was used on supra's way before they put it on Celica's. The good thing about it is that your car will always make it's own adjustments to make the most out of any modifications that you do to it. Probably part of the reason why Celica guys can slap an intake and an exaust on thier car and go from a 15 sec 1/4 mile to a 14.4 sec 1/4 mile, or put a 50 shot of NOS on thier car and get into the mid 13 sec. range. Well, that and the high compression, but the vvti technology is a really good thing to have on your car. :)

yea but i believe our cars have an OBD2 ECU?? or is that for hondas only.. well i thought all the newer ones had that **** in the ecu where it adjusts to ur mods.. which is why everyone resets their ecu after they get mods, or they just do an override.

[chameleon]

Yes, the ecu on all newer cars do make adjustments to things like fuel enrichment when you modify something, but the ecu does not make adjustments to the valve timing. Only vvti and i-vtec cars will do that.

[ludatic]

Originally posted by chameleon
Yes, the ecu on all newer cars do make adjustments to things like fuel enrichment when you modify something, but the ecu does not make adjustments to the valve timing. Only vvti and i-vtec cars will do that.

alrite so resetting the ecu is still required, unless u do the work-around.

since it adjusts to the timing, does that mean those adjustable cam gears are pretty much useless to i-vtec and vvti motors?

[dx3162]

I'm not positive ludatic, but im guessing a part that either advanced or retards the timing on your motor may be useless if your motor can do it electronicially and change it continuosly through the RPM range. Just my guess. ;)

[BB_GT01]

It seems that some of you are confusing variable VALVE timing and variable IGNITION timing. They are very different things. I think that VVTi is all about VALVE timing. The ecu may adjust ignition timing, also, but that's pretty normal, these days.