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Location:
Dubbo
Registered:
April 2005
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Disabling TVIS
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Sat, 27 August 2005 13:48
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Hey guys,
Has anyone here disabled theirs? i wouldn't mind trying it if it is as simple as pulling a hose off and blocking the 2 holes left over from pulling said hose off.
Where abouts is the hose on an ST185?? i THINK i have managed to find it from some pics and a bit of guestimation, tho reluctant to pull it off til i am sure.
Regards Nathan
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Location:
Bundaberg, Qld.
Registered:
May 2002
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Re: Disabling TVIS
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Sat, 27 August 2005 22:01
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you will not gain anything from disabling the t-vis, but you will lose lower rpm torque.
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Location:
Newcastle, Australia
Registered:
August 2005
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Re: Disabling TVIS
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Mon, 29 August 2005 07:17
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Feral is dead on the money here, the TVIS is a beautifully engineered system that gives major benifit on stock or modified engines.
Check this site out for an in depth look at TVIS, with proven results.
http://www.speedtoys.com/~marcel/t-tech/tvis/tvis. html
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Location:
brisbane
Registered:
December 2004
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Re: Disabling TVIS
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Mon, 29 August 2005 07:28
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indeed but i disagree with modified engines depending on power but 400hp and its useless
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Disabling TVIS
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Mon, 29 August 2005 07:42
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| berad wrote on Mon, 29 August 2005 15:28 |
indeed but i disagree with modified engines depending on power but 400hp and its useless
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The theory doesn't change, just it's implementation needs to be modified.
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Location:
Brisbane, Queensland
Registered:
January 2004
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Re: Disabling TVIS
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Mon, 29 August 2005 07:50
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There is no point disabling tvis, as it does have its benefits.
BUT,
There is benefits in removing it. Where you lose lower rpm response/torque you gain in upper rpm response/power due to less restriction in the intake manifld.
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Disabling TVIS
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Mon, 29 August 2005 07:57
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| -==L=a=N=c=E==- wrote on Mon, 29 August 2005 15:50 |
There is benefits in removing it. Where you lose lower rpm response/torque you gain in upper rpm response/power due to less restriction in the intake manifld.
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Depends how you're looking at it. Ultimately, a functioning TVIS setup poses little restriction in the the runners, and no real benefit if the manifold flows more than the head (i.e. a 1GGTE)
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Location:
Dubbo
Registered:
April 2005
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Location:
Newcastle, Australia
Registered:
August 2005
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Re: Disabling TVIS
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Tue, 30 August 2005 03:07
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Disconnecting the hose will cause the butterflies to stay permanently shut, as the system requires vaccuum to be in an open state. If you pull the electrical plug on the vac solenoid the system will stay open. I strongly have my doubts that this will help to spool your turbo up quicker, as the whole purpose of TVIS is to increase cylinder filling at lower RPM, therefore increasing gas velocities through the head. Higher gas velocity sooner in the rev range equals more boost at low RPM.
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Location:
Dubbo
Registered:
April 2005
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Re: Disabling TVIS
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Tue, 30 August 2005 03:40
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umm the site u quoted before stated that they are held open by a spring and a vacuum causes them to shut.
And i know it won't help the car spool quicker, it is spooling ok now, hits 5psi quick enough, then stalls out til higher revs and doesn't add power til it starts to climb again, so i thought it MIGHT be cause the TVIS is restricting it.
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Location:
u.s.a. south
Registered:
April 2004
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Re: Disabling TVIS
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Tue, 30 August 2005 08:27
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on the mr2 u.s. forum there was an extensive post where someone raved about how TVIS spooled his turbo quicker and gave an un-natural v8-like low rpm torque curve.... great response, and tire smoke if wanted.
Sounds like the best of both worlds to me. I'm keeping my tvis
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Location:
Newcastle, Australia
Registered:
August 2005
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Re: Disabling TVIS
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Tue, 30 August 2005 09:18
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Well slap me with a moist trout Roundy your right, I just went out to the shed and looked at a set of TVIS butterflies and it is held shut by vaccuum.
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Location:
Sydney
Registered:
September 2004
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Re: Disabling TVIS
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Tue, 30 August 2005 09:19
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| GTtwin wrote on Tue, 30 August 2005 13:07 |
Disconnecting the hose will cause the butterflies to stay permanently shut, as the system requires vaccuum to be in an open state. If you pull the electrical plug on the vac solenoid the system will stay open.
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This is incorrect unfortunately.
The TVIS butterfly is spring loaded open. However it is managed by a vacuum tank that is connected between the TVIS actuator and the manifold.
this tank has a one way valve on the inlet side which shuts as manifold vacuum decreases therefore maintaining a constant vacuum to the actuator.
Between the vacuum tank and the actuator is the TVIS VSV, once engine speed of between 4000 and 4500 rpm (depending on engine load) is reached the VSV allows atmospheric air to enter the system between the tank and the actuator causing the spring loaded butterflies to open.
This is necessary as manifold vacuum fluctuates and becomes nonexistent once boost pressure is reached. Therefore this system is deisgned to have the butterflies closed under 4500rpm and open above 4500rpm regardless of manifold pressure.
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Location:
WA
Registered:
May 2005
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Re: Disabling TVIS
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Tue, 30 August 2005 14:17
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errr, does my Gen3 1G GTE have a TVIS system?!?!?!
some dude recons u can adjust the system? i dont even know if i have one, and it doesnt seem like i doo judging by the side of the intake manifold and where it meets up to the block. . .
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Disabling TVIS
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Tue, 30 August 2005 22:25
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| VeeP wrote on Tue, 30 August 2005 22:17 |
errr, does my Gen3 1G GTE have a TVIS system?!?!?!
some dude recons u can adjust the system? i dont even know if i have one, and it doesnt seem like i doo judging by the side of the intake manifold and where it meets up to the block. . .
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Yes it does, but don't touch it on a near factory engine.
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Location:
WA
Registered:
May 2005
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Re: Disabling TVIS
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Wed, 31 August 2005 02:35
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hah! now that u told me its their, im gonna have to experiment, sorry man 
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Disabling TVIS
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Wed, 31 August 2005 02:42
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Experiment all you like, watch the power wittle away 
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Location:
Adelaide
Registered:
July 2002
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Re: Disabling TVIS
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Wed, 31 August 2005 02:49
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http://www.mrcontrols.com/primers/power.htm
on that site there is a section on how to change the tvis opening point using a rpm module thingy majiggy. seems like thats the way to do it.
Excert from site
The intake manifold and TVIS were designed to provide good low end torque and high top end flow using a dual runner per port setup with a set of butterfly valves kept closed at low RPMs to increase air velocity into the port and open at higher RPMs to increase flow capacity. The proper TVIS opening point lowers as VE improves (better exhaust, turbo, valves or cams). The ECU keeps a fixed opening point around 4200RPMs which is too high for modified engines. Consequently, there will be a torque dip from around 3800 RPMs to 4200 RPMs. The ECU also uses the TVIS to reduce engine VE if it has detected knock in the recent past. This can cause variations in performance for no apparent reason. The TVIS be kept functional as long as you continue to use the stock intake manifold but you should control the TVIS with an MSD RPM switch. You will need to purchase an MSD 8950 along with an appropriate RPM module, which is going to be included in wither the MSD 8743 (for even 100 RPMs) or MSD 87431 (for odd 100 RPMs) opening points. Alternatively, you can make your own fully adjustable RPM module. Most modified 3S-GTEs will need to open the TVIS between 3600 and 3900 RPMs. The only way to know for sure is to do a dyno pull to 4500RPMs with the TVIS open and another one with the TVIS closed keeping everything else the same. Then, the point at which the two torque curves cross is your best opening point.
The best place to install the MSD 8950 switch is in the engine bay near the igniter/coil. Cut the red and blue loops on the switch since you are going to run on a 4-cylinder engine. Ground the black wire to any bolt that goes into the chassis. With the ignition key off, pull the 2 pin connector from the coil and splice the red wire of the switch to the black wire with a red stripe. Splice the white wire of the switch to the black wire with a white stripe. I recommend using good solder or crimp connections to do this. Plug the connector back into the coil. Now go under the intake manifold and locate the TVIS valve. This valve has one vacuum hose going to the TVIS actuator, another vacuum hose going to a blue/purple canister mounted under the intake manifold and a 2-pin electrical connector. Disconnect the connector and cut the green wire with a black stripe about two inches from the connector. Cover the end of this wire from the engine harness with electrical tape. Connect the other end of this wire going to the connector to the gray wire from the MSD 8950. Use a pair of spade connectors so that you can easily set the car back to stock or control the TVIS by hand to help you find the switch point at the dyno. Reconnect the connector
For the interim, install a 3800 or 3700 RPM module in the switch. Now you just need to find the best switch point at the dyno as explained above. To keep the TVIS open, you can disconnect the gray wire from the TVIS control valve and leave it hanging in air. To close the TVIS, ground the wire going to the TVIS valve. If you notice no difference, your TVIS system is not working properly and you must follow the directions in the BGB on how to diagnose it.
Cheers
[Updated on: Wed, 31 August 2005 02:51]
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