Toyota's T-VIS

[James]

I found this on the site that Mikko posted within all the crazy Archives, explaining how T-VIS works, basically its just a more Detailed version of how Redlyne_MR2 explained it......Screw Vtec!....T-VIS all the way!:D j/k



"Most early 4-valve engines were not good at low-to-middle speed torque, simply because the larger intake area resulted in slower air flow. Especially at low speed, the slow air flow in the intake manifold led to imperfect mixing of fuel and air, hence knocking and reduced power and torque. Therefore 4-valve engine was regarded as strong at top end but weak at the bottom end, until the technology of variable intake manifold became popular recently.

However, Toyota had already found a solution as early as the AW11 / AE86 era. The 4A-GE engine employed a patent T-VIS (Toyota Variable Intake System) to accelerate low speed air flow to the manifold. The theory was quite simple: the intake manifold for each cylinder was split into two separate sub-manifold which joint together near the intake valves. A butterfly valve was added at one of the sub-manifold. At below 4,650 rpm (some sources said "around 4,300 rpm" though) the butterfly valve would be closed so that raising the velocity of air in the manifold. As a result, better mixing could be obtained at the manifold (excluding direct-injection engines, fuel injection always takes place in the manifold).


http://jimmysteele.tripod.ca/mr2_tvis1.jpg http://jimmysteele.tripod.ca/mr2_tvis2.jpg http://jimmysteele.tripod.ca/mr2_tvis3.jpg

There’s a common misconcept saying the T-VIS transformed the engine effectively into a 2-valve one at low speed. In fact, all intake valves always breathed because the sub-manifold jointed together near the valves."

Copyright© 1997-2001 by Mark Wan

[midship]

I hate to say this but IMO Vtec is still better than T-VIS. You will lose high rpm range power because your cam profile is unchanged. You do need higher lift to extract power at the higher end. That's is why Toyota had the BEAMS engine ( basically the VVTi-l ) or one example is the 4AGE 20V. :)

[Redlyne_mr2]

Originally posted by midship
I hate to say this but IMO Vtec is still better than T-VIS. You will lose high rpm range power because your cam profile is unchanged. You do need higher lift to extract power at the higher end. That's is why Toyota had the BEAMS engine ( basically the VVTi-l ) or one example is the 4AGE 20V. :)
or you can have a win win situation and buy an mr2 turbo...tvis low end and a turbo for the top end:thumbsup: takes vtec to school:D..you should know all about that midship

[GTS Jeff]

Originally posted by midship
I hate to say this but IMO Vtec is still better than T-VIS. You will lose high rpm range power because your cam profile is unchanged. You do need higher lift to extract power at the higher end. That's is why Toyota had the BEAMS engine ( basically the VVTi-l ) or one example is the 4AGE 20V. :) ure a fool. this has absolutely nothing to do vtec...unless ure talking about vtec-e or 3 stage vtec.



anyway, tvis aint that great, my car still has no lowend. maybe my tvis is busted..

[midship]

Originally posted by Jeff TYPE R
ure a fool. this has absolutely nothing to do vtec...unless ure talking about vtec-e or 3 stage vtec.


Yup, maybe I am a fool however we are comparing 2 system which both are trying to extract low end torque out of the engine. The basically design of the Vtec system is to run a lower profile cam lobe to increase low end torque, whereas T-VIS do it in the way of increasing the speed of the intake air to the cylinder.

Of course T-VIS is not remotely equal Vtec or vice versa. T-VIS car use constant cam profile ( e.g. 3S-GTE ) and varialbe intake track whereas Vtec use contant intake track and variable cam profile.


Originally posted by Jeff TYPE R
anyway, tvis aint that great, my car still has no lowend. maybe my tvis is busted..

I do not know what kind of car you drive? Your sig says AE86. I do not know you 4AGE has TVIS but I wouldn't expect a lot fo torque from a 4AGE anyway. 4AGZE is a different story.

Redlyne_mr2 - Haha, I am a fool what do I know :dunno: :rofl:

[GTS Jeff]

Originally posted by midship


Yup, maybe I am a fool however we are comparing 2 system which both are trying to extract low end torque out of the engine. The basically design of the Vtec system is to run a lower profile cam lobe to increase low end torque, whereas T-VIS do it in the way of increasing the speed of the intake air to the cylinder.

Of course T-VIS is not remotely equal Vtec or vice versa. T-VIS car use constant cam profile ( e.g. 3S-GTE ) and varialbe intake track whereas Vtec use contant intake track and variable cam profile.



I do not know what kind of car you drive? Your sig says AE86. I do not know you 4AGE has TVIS but I wouldn't expect a lot fo torque from a 4AGE anyway. 4AGZE is a different story.

Redlyne_mr2 - Haha, I am a fool what do I know :dunno: :rofl: if u want to compare systems that extract low end torque from an engine, then u should also include turbo, nitrous, larger displacement, longer stroke, etc...basically, your statement that vtec is better than tvis is like saying turbo is better than tvis.

and i know how vtec works. do you? (http://forums.beyond.ca/showthread.php?s=&threadid=5372&)

anyway, my ae86 has a first gen 4age...which has tvis. its the later model 4age engines that phased out tvis.

[GTS Jeff]

fool :nut: :D

[Redlyne_mr2]

I dont understand why tvis was phased out in the latter gen 4age and yet they put incorporated it in the 3sgte:dunno:

[GTS Jeff]

Originally posted by Redlyne_mr2
I dont understand why tvis was phased out in the latter gen 4age and yet they put incorporated it in the 3sgte:dunno: oh, cuz they raised the compression ratio to 10.something and didnt need tvis no moe

[midship]

I didn't start the comprison , James did. :D The reason why I posted was because I do not like people just say Vtec or T-VIS is the s$%^ kind of blanket statement. Every system has their weekness and strong point. I won't like to see this thread becoming a Honda vs Toyota since I think both of them make great cars just different approach.


I am no T-VIS hater since I do have it in my car and I like it. :thumbsup: I do not know why you are so tick off. :dunno:

[GTS Jeff]

Originally posted by midship
I didn't start the comprison , James did. :D The reason why I posted was because I do not like people just say Vtec or T-VIS is the s$%^ kind of blanket statement. Every system has their weekness and strong point. I won't like to see this thread becoming a Honda vs Toyota since I think both of them make great cars just different approach.


I am no T-VIS hater since I do have it in my car and I like it. :thumbsup: I do not know why you are so tick off. :dunno: heh im no tvis hater either cuz i have it too...

i aint ticked off...i just like to argue...its all good

[midship]

:confused: :thumbsup:

[three.eighteen.]

err no TVIS is not a VTEC equivalent, toyota's take on VTEC is called VVT-i, i've heard of some guys removing TVIS for more high end power even, but less low, BMW had a similar devince on their 4-cyl engines called DISA (short for some german thing basically meaning dual resonance intake runners)...and antoher thing, thers no way theres a 4agze in jeffs car, they were never even made for a FR platform as far as i know, the only way to you a longditudinally mounted 4agze is a from a swap the only cars to come with the 4agze stock from toyota was later first gen mr2s and i think some jdm FWD corollas (sprinters and levins)

[GTS Jeff]

Originally posted by three.eighteen.
err no TVIS is not a VTEC equivalent, toyota's take on VTEC is called VVT-i, i've heard of some guys removing TVIS for more high end power even, but less low, BMW had a similar devince on their 4-cyl engines called DISA (short for some german thing basically meaning dual resonance intake runners)...and antoher thing, thers no way theres a 4agze in jeffs car, they were never even made for a FR platform as far as i know, the only way to you a longditudinally mounted 4agze is a from a swap the only cars to come with the 4agze stock from toyota was later first gen mr2s and i think some jdm FWD corollas (sprinters and levins) dude, theres a 4age in my car...which is different from a 4agze. and actually, 4agze's WERE made for the ae86...in australia :)

[James]

First of all i didnt mean for this to be a T-Vis v.s Vtec battle AT ALL!! i was joking! (hence the "J/K" ).......i know they are two totally different systems, designed by two Different Companies which make GREAT CARS in thier own right, I will never doubt the fact that Honda makes astonishing Engines, i just think Toyota makes better! :D lol....up until last week I only had a vague clue of how T-Vis worked, All i knew was that my Engine Got Louder at 4600 Rpm's and that this thing labelled "T-Vis" in my Engine bay most likely had something to do with it.
Last week Ryan Gave me more of an idea how T-Vis works, and when i Found this Article i just thought i would share it with the Board, as some of us have T-Vis engines, And Im sure the Majority of people have either never even heard of T-Vis, or only have a Rough Understanding how of it works. And im pretty sure this Article most likely clears up any or most misconceptions or Questions about T-Vis.
As well Articles like these are good peices of information to be stored in the Archives of any Forum. As Im sure later down the Road, some Guy who just bought an older Toyota, and was Curious about T-vis may do a Search and this kind of Article will show up.......ahhhhhh im Done. For now :)

[Redlyne_mr2]

Great way to contribute to the board James, TVIS is a bit harder to explain than vtec and youve made it easier for others to understand. I hope were not all argueing about vtec vs tvis because almost all the people who responded to this thread own Toyota...:thumbsup: