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Discussion Starter #1
awhile back i posted my car was havin some problems. finally started getting into and found that one of the butterfly valves in the intake manifold was gone. i was told this is part of the tvis and it can be gutted. im not familiar with this design and would like any info on whether or not thats a good idea or if theres an aftermarket replacement or should i just fix it. i havent got into the engine yet to see what damage was done. depending on how far it went will determine if im gonna fix it or just go ahead and get a jdm swap.

i also found that my exhaust manifold is cracked too so im looking to buy an aftermarket one with downpipe and was wondering what brands are good to go with and which to stay away from.

my car is a 91T with ats ct26 upgrade and tb inlet, tko exhaust, mbc, KN intake, and the rest is stock. while the head is off definitely gonna upgrade the valves and springs and was considering cams and cam gears. with the upgrades i already have will they be worth the money tho and which degree would be best? i wanna try and do as much as my money will allow while everythings apart.
 

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After reading several threads and info on the TVIS, it seems like a glorious idea to me. However, unless you are moving massive volumes of air (as in full drag setup) it is unnecessary and even in those situations it is just one more thing to go wrong without much gain on the upside. My vote - can the TVIS, just pull off the remaining butterflies and cap the vac lines. Just finished motor install on a 91 and gutted it for customer, no noticeable difference.
 

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Discussion Starter #3
thanks for the advice..i guess if it doesnt cost any money to do it and its not gonna lose power then whats the harm if it might actually benefit me later.
if anyone else has any suggestions id appreciate it.
 

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WishIOwned1 said:
After reading several threads and info on the TVIS, it seems like a glorious idea to me. However, unless you are moving massive volumes of air (as in full drag setup) it is unnecessary and even in those situations it is just one more thing to go wrong without much gain on the upside. .
I think you are a little confused about the function and purpose of the TVIS. It is NOT a system to improve air FLOW, nor does it even come into play when you "...are moving massive volumes of air ...".

Its purpose is to increase VELOCITY at low RPM/low airflow conditions. It improves low end perfromance and throttle response by restricting airflow and increasing velocity.




bill

bill
 

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So does it make enough of a difference to keep it, for those of us not wanting just an all out drag car? Low end is important to me, but I'm a little concerned about those pieces breaking off.

**edited for spelling
 

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Some say yes, some say no. There are a few people who have made 200ft/lbs of torque below 3000 without the TVIS.. Mine is gutted, and I have excellent low end, but that could be mostly attributed to my stroker.

In the end its up to you. If you plan to make gobs of horsepower, the butterflies and shaft are just blocking air. If staying below the "I need an EMS now" stage, there's really no reason to gut it.
 

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Discussion Starter #9
so what affect will doing away with it have on the performance with the setup i have if any? what about later when i get a bigger turbo? or should i just fix it?
 

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MrChrisB2 said:
so what affect will doing away with it have on the performance with the setup i have if any? what about later when i get a bigger turbo? or should i just fix it?
It improves low end!

If its disabled, there will be a loss of low end perfromance and throttle response.

bill
 

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Discussion Starter #11
thanks bill thats what i needed to know..i dont need to lose any bottom end power so i guess i need to fix it then..is there anything special required or is it simply just bolt a new butterfly valve in there?
 

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Just to make sure, are you saying that one cylinder has no butterfly at all? There are eight intake ports and four should have butterflies. If you have only three, then I would suggest checking for someone that has the complete unit for sale.
 

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Discussion Starter #13
yea there is 3 in there still and 1 is gone...the car was runnin real rough and i could hear some noise comin from the head like there was a loose piece of metal bouncing around in there. we havent had time to get the head off and see just what amount of damage was done but if its gonna end up costing much more than $1000-1500 i think im just gonna go and do a jdm gen2 swap with it.
 
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