TVIS?

[Ivan141]

That's a matter of preference I guess. The only way to know for sure is to test it on a dyno..
Or do it the sloppy but easy way, disconnect the vacuum line or electric connector to the TVIS solenoid and it will be permanently opened. If you like it better that way you should take TVIS out. Dont forget to plug the vacuumline with a bolt if you disconnect it..

[NoHachi]

Tvis should also work on a 7A-GE engine. Any engine could use differently tuned runners at different rpms...
I do think that the ideal switching point of the TVIS will change...so you would have to check things at a dyno and possibly add a rpm-switch yourself.

[chadix7age]

oh ok. i really thought that the extra displacement would compensate for it. guess i will keep it then?

[Apolan]

On the subject of 4ag vs honda. Before hachi i hade a 4th gen civic ('90) w/ a d16a9 (i think). This is also the 1600 ccm 16 dohc engine, w/ similar outpt 130 hp.. aso the car wighted around the same as the 86.

It can still be felt - the honda engine (which is similar to the ZC ivan mentioned) pulls harder and harder as the rpms increase. No vtec here. it has a redline at around 7500 rpm, but you feel alot of power above 7000. Im pretty confident it would make quite some powere over 7500 too. Though w the 4age there is more torque down low. And its not fun to push it over 7000 or 7300 perhaps.. The car is more jumpy at low rpms. Perhaps this is the combination of better response, tvis, rwd etc. But it definitely feels different than the honda unit, although the specs are similar.

I read on bill Sherwoods page that it would be sensible to keep the TVIS i f you have cams that are less then 260' duration:

Quote:Note that with cams larger than about the 260° mark you will actually benefit from removing the TVIS, if fitted. The TVIS, when used with cams smaller than about that duration, will give you more low end ( < 4,400rpm) power, but this effect disappears with the bigger cams.

[Big T]

Heya guys, 1st post here

The 1g-gte has a TVIS system from the factory as well so it can be made to work with a turbo engine too. Having said that, i've removed mine due to a turbo 4age setup with 272 cams. I think it would be interesting to try and play with the changeover point to try and gain some low-down drivability though. Too much dyno time ($$$) needed for my liking though.

I know a guy running stock gze computer with a td04 wrx turbo who originally had the TVIS removed. Couldn't get the thing to idle/rev smoothly below 2500rpm. Refitted the TVIS and got perfect drivability.

Eddie.

[D.Wars]

to dust of an old topic.

Last sunday I went to a driftday with my car.
In 2nd gear i could go round the track without a problem. It wasnt that easy in 3th gear. When I kept it in the 16v area I had enough power to pull trough. But when it just got in to the 12v area it just lost to much power to keep the car in the drift. So there has to be a big dip in the powerband at 4k rpm? I havent got time to dyno it yet, but should the diffrence between 12v and 16v be that big? Now im seriously thinking about removing the T-vis.

[Denmark]

Tvis has nothing to do with 12v or 16v,
Tvis just closes a inlet runner in the inlet manifold , but when the air gets to the head, it still goes to all valves!, as it´s one big hole


It´s just the natur of the engine, that wants it to be reved over 5k rpm ,to be in the powerband


h
/skassa

[D.Wars]

really? I always assumed that the t-vis switched off/on an extra inlet valve . But what and how do i have to modify to dismantle the t-vis?
I fairly new to toyota engines

Then I'll test it for myself what I think it drive's better for me.

[Apolan]

T-VIS is a set of butterflys thats located between the intake manifold and engine head. It closes one manifold port of the pair for each "head" intake port.. so it narrowes down each of the the intake ports by half (imaginea having a smallport head in TVIS range).. than it opens above 4000 or whatever rpm to utilise full area of the inlet port.. the narrower pert in the tvis range creates a venturi effect (speeds up the gasses).. above certoin rpm its just an obstruction, so it opens up..

[Ivan141]

Chances are disconnecting TVIS will help nothing, and possibly make it run worse at low RPM's. 3rd gear drifts with a stock 4age are possible, but you lack the most important ingredient I think...entryspeed. Zax would be the expert in this department. If you want to pull of slower drifts in 3rd I suggest you go looking for a shorter end-reduction.