ok i have a few questions.... i would think these would be simple... but who knows...
I have a tial 50mm BOV and tial 38m WG.
the BOV vacuum line i ran to an extra port on my carb.... but it seems to open the BOV at idle... like just sitting there with the engine running, you can see the bov valve kinda just floats there about half open.... just doesnt seem right to me.... first of all, what good is an air cleaner when this thing leaves a huge hole in my intake system for crap to get sucked into? I imagine that off idle the loss of vacuum will allow it to close... and then under boost it will help to keep it closed... but just dont like the idea of this being open at idle....
then the wastgate... it is the tial 38mm WG... dual ports.. one on top, one on the bottom/side... I have heard some people dont use vacuum at all, and just let the spring do all the work... others yet use an electronic boost controller and hook both ports up for better control of the wg... i know vacuum on the top ports helps to OPEN the WG... and vacuum on the bottom ports helps to keep it closed. likewise, pressure on the top closes and pressure on the bottom opens.
so how do you suggest i hook mine up? at least for break in and tuning... then i can tweak later on.
oh and also.... i am twincharged.... so i have manifold vacuum/psi (turbo and blower combined) and pre blower/ turbo only psi, and then atmospheric pressure.... so where am i best to hook what up where? (not sure how many can help with twin charging issues...) but in general for a turbo , what is the norm?
Is it a 2 barrel or 4 barrel carb?
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Mitsu TD06-20g |3" Turbo-back Exhaust | 61mm Bored TB |
HP Tuners | Innovate WB02 | Spec Stage 3 | Team Green LSD | TurboTech Upper | Full Addco Sways | Sportlines & Yellows |
BlackEco wrote:Is it a 2 barrel or 4 barrel carb?
oh shut up... you know what i mean!!! throttlebody... shesh, people are soooo literal...
Bottom port on WG.
You may need a different spring for the BOV, based on the vac. that your engine produces at idle. Slightly open is also about normal for that BOV it seems.
Edited 1 time(s). Last edited Sunday, September 07, 2008 6:48 PM
the tial bov is supposed to be like that, so there is better throttle response down low....mine does the same
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It sounds to me like the BOV is staying open TO far, even for that model, I would see about getting a different spring.
The WG, HAS to have a vaccum source hooked up to it.....period.
The tial 38 needs a vacuum source from your charge pipe BEFORE the throttle plate.
and yes, it goes into the BOTTOM port. If you run a boost controller, then you need to use the top port AND the bottom port. But the springs NEED a vacuum sugnal to operate, otherwise the WG wil never open.
Ok, so bottom port on the WG hooked to the charge pipes or other source PRE-throttle plate... But now with a BOV that is open at idle... do i want the WG source between turbo and BOV, or between BOV and throttle plate?
At idle, I assume the WG would be closed, and all exhaust going thru the turbine.... so the charge pipes would have some slight positive pressure... But with my bov partially open at idle, and throttle plate closed, i imagine any pressure seen would be released out the BOV... the vacuum would be on the engine side of the TB... Between TB and BOV would register Atmospheric pressure or ever so slightly below at idle based on what ever suction there was between the closed TB and the open BOV
so hooking the WG anywhere upstream of the TB should never see vacuum... it would always be atmosheric pressure or boost... right? is this what you want on a WG?
0 psi on the bottom port would just be spring pressure alone... which i imagine would typically stay closed.... (unless you had some crazy high exhaust pressure....) and then under boost, the pressure would work against the spring, and assist the exhaust pressure in opening the WG and allowing the turbine to stay within a given pressure range.
And then the BOV... i assume this should be a manifold vacuum source? so it sees both vacuum and pressure? (vacuum lets it open at idle, and then under cruise a neutral-ish pressure allows the spring to close it, and then under boost, the pressure seals it closed until the TB closes and creates an instant vacuum resulting in that oh so enjoyable PT-PSSH sound...)
well exhaust pressure will never open the wastegate valve. basically inside the head of the wastegate, where the vacuum line goes in, the charge pressure goes through the vaccum line, and pushes on the diaphram inside. the springs in the top push AGAINST the boost pressure goin into the vacuum port.....not the exhaust pressure.
here is Tial's installation diagram that might also explain it better.
http://www.tialmedia.com/documents/w3_tial_wginstall.pdf
The vacuum is after the throttle plate, but your turbo is not spinning enough to create a positive pressure. more like running the car with the hood off and a slight breeze going directly into an intake.
The BOV sees both pressure and vacuum. It SHOULD be closed all the time, until it sees a vacuum spike, the vacuum spike will make the valve open, but it should technically only open during a spike.
Some BOV's like my Greddy type S also have a boost port, that takes a line from the same location as the WG, and uses the turbos boost pressure to open the valve faster once the vacuum spike occurs.
here is the spring presures for the Tial 50mm, make sure your engine vacuum at idle is in the range of the spring you have.
http://www.tialmedia.com/documents/w3_tial_bov50_sp.pdf
Edited 1 time(s). Last edited Monday, September 08, 2008 8:19 AM
and then i know this is a path i walk down alone.... but you can all at least brainstorm and think along with me.....
as far as intergration between turbo and blower.... how would the turbo's vacuum sources effect the operation of the sytem based on their location in regards to the blower....
I cant imagine the BOV would care much if it was before or after the blower... and just above, it was explained that we want the WG hooked up BEFORE the TB.... so i guess that rules out puting it after the blower... but someone one time told me that i need to be careful of where i setup the turbo vacuum lines in a twin charged setup... Was he just talking about "make sure you use charge pipes, and not manifold" like discussed above? or are there alternative way it could be hooked up, and what could happen in those cases?
One thing i plan to do is run 2 boost gauges... one in the charge pipes, and another manifold... this way i can see how the 2 systems are working together... charge pipes should show turbo pressure only, and the manifold will show me turbo + blower boost... and give me a better understanding of what they are doing, and how to adjust them better.
honestly.....I would ask one of the other guys thats twin charged about exact vacuum line routing and tapping locations.....
I understand what you are saying, but can not say for sure what is correct, and what is not.
off topic, but speaking of pressure... what kind of oil pressure should i see in a 2.4L with the 2.3L oil pump conversion? (i have an actualy oil pressure sender and gauge now... as opposed to a on-off sensor and dummy light...) so just curious what my oil pressure gauge should be showing me most of the time... like what would be safe, and what should i worry about?
ok as far as the bov opening at idle, my engine sucks about -20psi at idle at peaks to -25 or more under sudden decel.
so i assume this "sucks" more than most engines so it is possible i just need a new bov spring??
I wouldnt consider that to be more than normail, but you need to make sure it is within range of the spring you have (see chart linked above).
20-25" hg is fairly normal for a car with "stock" cams. I was using HO cames when I purchased that spring thats in the BOV and I was only seeing maybe a spike to 20" hg. Like I said before, you probably need a different spring.
