This funny wee TVIS thingy

[Ako]

Ok, was tinkering with the engine the other night. Now, the stock turbo / mani setup has all kind of vacuum ports and solenoids everywhere, all seem to be related to the TVIS system.

Now, with the turbo on this car I'm not expecting any low end power, and I'm not aiming for all round driveability - just the ability to overtake in 3 seconds flat and scare passengers.

Now - would it be easier for me to just pull the little TVIS butterflies off the shaft and forget about it altogether, or do I connect the little canister controlling the butterflies up to a post TB source, or am I going to have to get creative?

[MrOizo]

Just drill the butterflies off and take the shafts out..

Make sure that you block up the holes where the shafts were

[Leon]

disconnect the Tvis and try driving it?

Painfully slow.

I got to try that after a mechanic blooper on my MR2. It was *not* a pleasant experience. Under 4400rpm it accelerated like a Fiat Bambina, I kid you not.

[Ako]

Oops.

Ok, need to clarify.

This car isn't running the stock exhaust mani anymore - got a stainless tubular jobby with a big turbo on it. Engines not actually in the car yet, hence why I'm asking this question before it goes in and becomes a pain in the bum to work on.

The stock TVIS had a port coming from the WG actuator on the stock turbo - I don't have that actuator anymore, and its running an external WG now. So - should I just go off a pressure source on the manifold, or should I just ditch the TVIS altogether?

The turbo is a TD-06 25G, and the past owner has said it only really came alive past 4500rpm anyway, so the low end isn't a concern. If its not fast enough, I'll drop back a gear. Just trying to figure out what to do with this aspect of things - I've seen some people remove it, some say leave it.. Its a bit conflicting. My last VR4 had a similar system, I pulled it out and it got what seemed like better top end, didn't notice any low end loss.

[MrOizo]

how about finding some one with a TVIS equipped car and going for a drive (alot of driving from stationary) and then disconnecting the TVIS and comparing. honestly it is lame and as was said

Under 4400rpm it accelerated like a Fiat Bambina, I kid you not.

It is like that. If you dont mind having to revv out a bit more then get rid of it. Would do a favour for your top end. less turbulating flow due to less obstructions in the air flow path

[sergei]

This is not the case for 3SGTE, as without tvis my boost peaks at ~3000rpm, and actually pulls better than with buterflies in place.
I did not just remove buterflies but I also smoothed the transition from 2 to 1 ports, as originally the TVIS plate hadsquare edges...
+ most of the time TVIS actuator has cracked membrane resulting in buterflies open all the time.

[Malcolm]

on the 3sgte in my old gt4 I didn't notice any different between driving with TVIS operating and with it disconnected

In the mr2 I have removed the TVIS plates, you can drill them off like Oizo says, but if you have access to a special piece of machinery known as a Philip's head screwdriver you can use that to remove them (provided you know how to operate such specialist machinery properly)

What might be more worthwhile is to take control of the TVIS operation and make the switch over at lower RPMs.

also:

The stock TVIS had a port coming from the WG actuator on the stock turbo - I don't have that actuator anymore, and its running an external WG now. So - should I just go off a pressure source on the manifold, or should I just ditch the TVIS altogether?

actually that's not related to TVIS, that is infact the turbo VSV which bleeds off a bit of pressure to make the car run higher boost (when the ECU wants you to)

The TVIS system comprises of the large purple vacuum cannister/plenum, and a smaller VSV, next to the turbo VSV, which controls the operation by connecting and disconnecting the vacuum from the actuator diaphram to pull the plates closed

[Ako]

This "Phillips Head" thing sounds a bit daunting to be honest...

But I'll give it a go. Cheers for clearing up the VSV thingy too.

At this rate it might even go one day!

[MrOizo]

..., you can drill them off like Oizo says, but if you have access to a special piece of machinery known as a Philip's head screwdriver you can use that to remove them (provided you know how to operate such specialist machinery properly)

I would have done that too if they hadn't been pressed on the opposite sides.