t-vis butterflies

oldae82
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t-vis butterflies

Postby oldae82 » Mon Dec 05, 2016 7:10 pm

I'm trying to build up a mild n/a 4age. Cams are tomei 264/ 8.1. Reading Bill Sherwood, (God, that blue background makes my eyes water) he indicates that one might as well disconnect the t-vis, because the effect of the opening in negligible with this cam spec. Should I remove the butterflies from the shafts?

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totta crolla
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Re: t-vis butterflies

Postby totta crolla » Tue Dec 06, 2016 1:59 am

In my opinion based on experiments with similar profiles I think that you are better off keeping the TVIS in place.
You can disconnect the vacuum pipe that goes to the plate if you want to keep the butterflies open all of the time, the vacuum closes the butterflies.
Doing this enables you to try with and without TVIS.
The price you pay is a very small air restriction from the butterfly spindle that would normally be removed when taking out the TVIS

oldae82
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Re: t-vis butterflies

Postby oldae82 » Tue Dec 06, 2016 7:21 am

thanks. Sounds like good advice.

Alex170984
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Re: t-vis butterflies

Postby Alex170984 » Wed Dec 07, 2016 3:16 am

Hi,

I have higher lift and duration cams than the tomei (though i really want some tomei poncams!!)

i have jammed my butterflies open and the difference in noticeable! I had absolutely no torque at the lower end and now i have some lol

It's a good idea to do - many people say it's a waste of time however the TVIS was designed for stock cams.

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oldae82
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Re: t-vis butterflies

Postby oldae82 » Wed Dec 07, 2016 6:14 pm

Thanks for the advice. One advantage of the fx is its lightness, so that any torque is noticeable. A/C is gone, power steering goes next. Need to start eating my Wheaties.

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Re: t-vis butterflies

Postby sirdeuce » Thu Dec 08, 2016 5:01 pm

IF, you do decide to go without the T-vis an option is to fill the shaft bores with aluminum based epoxy or weld them closed. Disabling the T-vis will make the car less traffic friendly, but doesn't really hurt if you are driving in a "racing" situation.
One shot, one kill.

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Rogue-AE95
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Re: t-vis butterflies

Postby Rogue-AE95 » Sat Dec 10, 2016 7:33 am

I think Techno Toy Tuning, and possibly others as well, make T-VIS elimination plates.
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sirdeuce
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Re: t-vis butterflies

Postby sirdeuce » Sat Dec 10, 2016 4:10 pm

TT a late for around a hundred bucks.
One shot, one kill.

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Re: t-vis butterflies

Postby davew7 » Sun Dec 11, 2016 5:20 am

If you are going down the the T-VIS elimination road, remove the plate completely. Just make sure you pull the locator dowels stuck in the head before attaching. You will have to source shorter attaching bolts that are 8mm x 35mm lg. If you have the time, $, and tools, get a new themo gasket for the head side, and fishmount each pair of the manifold ports at the head transition point. Dave W

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oldeskewltoy
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Re: t-vis butterflies

Postby oldeskewltoy » Sun Dec 11, 2016 9:09 am

If using an elimination plate check alignment.....

Image


I fixed the one above by slotting the bolt holes, and adding jack screws to the ends of the plate

Image
OST Cyl head porting, - viewtopic.php?f=22&t=300

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Re: t-vis butterflies

Postby sirdeuce » Sun Dec 11, 2016 3:28 pm

OST.
And after all that work would you say it was worth it? Is using the T-vis mani with a small port head, with adapter of course, good on the lower RPM ranges?" Does it do as well as the proper mani on that head? Sorry if it's off subject.
One shot, one kill.

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Re: t-vis butterflies

Postby Alex170984 » Mon Dec 12, 2016 4:16 am

I'm doing a small port conversion on my AW11 and I am not using the TVIS. I have gone to the trouble of sourcing a small port inlet manifold rather than doing the big port adapter and big-port inlet manifold.

I was under the impression the small port is better because of the head and manifold design and there is no need to run the TVIS and the later AE92 corolla didn't come with the TVIS anyway, so Toyota obviously determined there was no need for this.

I have mine jammed open currently as i am running high lift cams anyway.

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oldeskewltoy
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Re: t-vis butterflies

Postby oldeskewltoy » Mon Dec 12, 2016 8:10 am

sirdeuce wrote:OST.
And after all that work would you say it was worth it? Is using the T-vis mani with a small port head, with adapter of course, good on the lower RPM ranges?" Does it do as well as the proper mani on that head? Sorry if it's off subject.


It was a client's head... so you would need to talk to them. I can tell you this, the 4AG's flow can be hurt by poor manifold-port alignment.

Now speaking to smallport vs largeport: @ power levels around (approximate) 160 crank hp, the TVIS manifold becomes the obstruction, but below that level, when the engines are built similarly, they make similar power - so to answer your question about using the adapter on a smallport head, I recommend(in largeport equipped cars) for builds upto 150hp, keeping the TVIS, and the largeport head, and building the largeport to the same specs you were going to build the smallport. If your plan is to build the engine for more power(over 160hp), then the smallport manifold makes the better choice. The "other response" is ITBs.... but that opens a whole new can of problems in tuning, and aftermarket management.
OST Cyl head porting, - viewtopic.php?f=22&t=300

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Enjoy Life... its the only one you get!

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Re: t-vis butterflies

Postby Alex170984 » Tue Dec 13, 2016 3:52 am

oldeskewltoy - on a separate note what kind of power can a smallport put out if everything standard less mild cams say 256 in & ex?

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Re: t-vis butterflies

Postby SgtRauksauff » Wed Dec 14, 2016 1:36 pm

I run a 7-rib largeport, and I kept T-VIS. Not an overly crazy build: 0.8mm head gasket, 10.3:1 oem first-oversize pistons, stock exhaust manifold, cleaned the ports, but no bowl work. T-VIS was very noticeable, in sound as well as butt-dyno (and real dyno, I think this was 108 at the wheels.).

Then I put on a header and fpr, and some Toda 264int/256exh cams. Great increase under the whole curve, T-VIS was much less noticeable in noise, butt-dyno said it was less prominent of a change than with the stock cams. and lines on the dyno still showed increase during T-VIS activation. (133 on the dyno).

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Re: t-vis butterflies

Postby Alex170984 » Thu Dec 15, 2016 4:15 am

Hi SgtRauksauff, I'm doing a same sort of build on my AW11 but swapping the bigport head, inlet manifold and pistons to all smallport. But will be trimming head down to 35cc along with port work, deshrouding, polishing etc have 260/252 cat cams too. I'm going to ditch the TVIS completely.

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Re: t-vis butterflies

Postby SgtRauksauff » Fri Dec 16, 2016 12:23 pm

I do a lot of AutoX, and really wanted the extra torque at the bottom half of the curve for coming out of corners when you can't shift down, but aren't in the 'good' rev range yet. sounds like you're on-track to a fun machine!

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oldeskewltoy
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Re: t-vis butterflies

Postby oldeskewltoy » Fri Dec 16, 2016 3:14 pm

Alex170984 wrote:Hi SgtRauksauff,

swapping the bigport head, inlet manifold and pistons to all smallport.

I'm going to ditch the TVIS completely.


once you run the smallport stuff, you can't run TVIS... as TVIS only fits on a largeport head
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

Enjoy Life... its the only one you get!

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Re: t-vis butterflies

Postby Alex170984 » Mon Dec 19, 2016 8:28 am

Yes mate I know, I meant completely as i've currently got mine jammed open.

I'm sure i've read somewhere where someone has put it back on again, obviously with adaptor plates.

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