OK, lets say I was going to turbo a n/t 4g63 from a 92 esi for a friend. The block and head would be left alone and the turbo, injectors, ecu, fpr etc... would be used from an automatic tsi setup. Now the engine in this state would only be able to handle about 8 psi I have learned, which is fine but how do you hold only 8psi with a 13b wastegate actuator? (same as 14b, 16g etc.. I beleive) With out a mbc and boost solinoid, the car will run 11 psi or so. This is too much boost. Is there any way to run 8 psi while using the stock exhaust manifold, 13b actuator and related components or is getting a custom header with an external wastegate the only option. That could be very very costly.

If he used an aftermarket BOV such as a Greddy type s, would a mbc type device work on the line from the intake manifold to the bov instead? What I am trying to get at is can I some how set the bov to leak out the extra boost that is created from the wastegate actuator not working soon enough. Just a crazy thought I had

thanx

if you plumb the vacumm/boost directly to the wastegate actuator, it will run 8psi on a 14b actuator. I'm not sure how much the acutator on the 13G holds, but my guess whould be lower.

Jer, my 90 has the vaccume/boost line plumbed directly to the actuator right now and it holds 10psi. I am sure the actuators are the same. Autos and 5-speeds ran the same boost levels I was told, just different turbos. But then again, why were the injectors, fpr and cams different as well? I'll have to search some more for that one. Thanx though!

Some DSM Tuner guys told me to cut the actuator arm, shorten it then put a threaded coupling in between. Then adjust to desired boost level by adjusting the coupling. I have to think about this one for a bit. I cant picture whats happening in my head right now. I think it would work in the sence that I adjust the coupling to keep the gate valve open a little all the time. Does this make sence?

Wouldn't leaving the flapper door open a bit affect spool-up?

Is the vacuum line going directly from the compressor nipple to the WGA? Nothing teed in to it? That should give you no more than 8psi with a stock actuator. Does the arm move all the way, freely? Drop in a known good actuator, it's worth a try.

That would give you an even higher boost level, no?

Rob, I think that just because the actuator opens at 7 or 8psi in the vaccume line doesnt mean there isnt more boost in the ic system. Correct me if I am wrong but lets say the stock actuator opens at 8psi from the vaccume line. This means there is 10psi or more in the intake system because the vaccume line has different preassure properties being so small. (this is just an educated guess, i could be talking out my ass)

All I know for sure is my 90 has no mbc on it right now. The vacume line is connected form the j-pipe nipple to the actuator nipple with no "T" or anything, just a dirrect connection and it holds 10 psi.


edit: btw, leaving the flapper open would affect spool up but thats what we want, less than stock boost. For 8 psi, I think it will spool plenty fast with a 13g. Once again, I could be wrong, just making guesses here.

The reading at the compressor housing should be the highest, since it is taken right after the air is compressed. So if anything, reading from anywhere else or bleeding off any pressure before the WGA is going to give you higher max boost levels.

So if the compressor spools 8psi and sends 8psi signal to the WGA (opening it completely), you should never see above 8psi - unless there is something wrong with the WGA (not opening when it should), or the WG itself is not opening enough (letting enough exhaust pass by) to limit the boost.

I'm pretty sure my ass isn't the one talking here

So why does my 90 run 10 psi then?? I am confused now!

Edit, I thought stock boost was 10-12ish psi.

That's the right figure if you have the stock BCS in line. It is bleeding pressure back to the intake (before the compressor), and gives a signal of 8psi to the actuator when you are actually running 10-12ish psi. If there is knock the BCS closes and gives the full 8psi to the actuator when you are at 8psi boost.

With an MBC, you restrict the pressure getting to the WGA so that at X boost pressure you are sending 8psi of pressure to the actuator.

I have no boost solinoid and no mbc right now and it runs 10-11 all the time. That is why I think its incorrect to call them 7 psi (or whatever) actuators because thay actually allow the intake to hold 10-12, depending on how much the actuators springs vary. If you have 10 psi in the intake, the vaccume lines are only sending 7 or 8 psi. Make sence?

So if this is correct I would have to find a 5 psi actuator for this conversion in order to run 8 psi or have an external WG setup.

But if you have 8psi at the compressor housing, what would you say the pressure is at the intake manifold? If anything, wouldn't it be LESS than 8psi?

You are sending 8psi to the actuator, it should actuate.

HMMMMM, I cant answer that Rob. I am confused now. So if what you are saying is correct, both of my talons have faulty actuators because they both run 10 psi with no mbc and no bleeder solinoid with the vaccume line running from the j-pipe nipple to the actuator nipple directly. My 90 has been like this for some time now. I tried it on my 91 over the summer when my mbc screw fell out so I hooked it up that way till I could make another and it too ran 10 psi.

Another point I think you are missing is that if your compressor housing is sending 10 psi, the vaccume line isnt. I think its a couple psi lower in the vacume line. Thats the whole point I am trying to make here and trying to confirm.

I can't confirm or deny that. It wouldn't be much work to find out... Just get a bigger vacuum line!

"Ported vacuum line."
Add that to the mod list

If you have some spare time, why don't you test your theory?
You'd just neeed an intake leak tester, compressor and pressure gauge.
Compare what you are putting in to the turbo to what is coming out of the signal line.

I'll be sure to tell Josh to add that ported vaccume line to the parts list. As for the theory, I'll check that with my leak tester some time this week. Good idea.

In the mean time, can anyone else think of a way to hold 8psi?

"T" a boost guage directly off of the turbo->WGA line and read the pressure at full boost. Then get rid of the "T", run them directly, but connect your boost guage to your intake manifold. Record the difference, you`ll be able to see how much pressure drop you have. Should not be more than 2psi from the turbo, or more if you have a fmic and so forth..

If you want my opinion, I don't then there's a way of running LESS boost just because the deciding factor is the WGA which has the 9-10psi as the MINIMUM before it opens, bleeding this off and block off that will do nothing except RAISE boost.

The only way I see this working is with the whole flapper thing open a bit to de-crease spool-up but it will also not work because it would only 'cause the turbo to spool slower, but the WGA would still provide the same resitance one you reach full boost, still putting you at 10-11psi or whatever you said you were at.

If you want to change the way the WGA works, you`ll have to cut it open, and replace the spring with something softer. Hope this helps:)

In theory, if you plumb the line directly from the turbo J-pipe to the wastegate actuator, you should see only 8psi. I tried it on my car and it held 8psi.

Now, if there is a leak on that line or a pressure drop due to restriction (there shouldn't be any since its a pressure wave) you will see a higher boost lvl. I can almost garantee that a 14 year old actuator isn't as sensitive so that might explain your higher lvls.


why 8 psi?

why just run 10psi?

(I have a spare almost mint cond N/T motor I was thinking of dropping into my talon..run 10psi..just have to keep an eye on the EGT and knock)

Thanx for the input guys!

Rob when I did the conversion I used a stock 13g with a stock wastegate from a 13g on a NT engine.
I had a problem with boost control.
When I floored the throttle, the boost would almost be instant and it would spike to 15psi and higher!(my boost gauge only reads up to 15psi)
It would settle down to 10-11psi.
Keep in mind that I also have the WG hooked directly to the Turbo elbow.
Thinking that the WG was sticking, I switched with another one.
Still had the same problem.
My guess with boost spike, is that the Vaccum line is to small of diameter and thw WG can not react quick enough.
And all the talk about hooking up the WG vaccum line dircetly the the turbo elbow to run 8 psi is bullshit. It will run @ 11-12psi.
Anyways how I slove this is installing 1/8" washers between the WG actuator and the turbo housing.
[img]http://www.geocities.com/tcvaz/TurboWasher3.txt[/img]
You could also do the thread the actuator arm thing, but to much like work.
Anyways hope this helps.

Yeah Tony, I know it will run 10-12psi, I seen it with my own eyes on both my cars. I thought I was going crazy there for a second with all the confusing replys but thanx for confirming my point.

I'll try your way, thanx for the tip!

When are you planning to to this? I may be able to come out a lend a hand.
One more thing,
The car runs great but there are knock issues with the conversion.
But that might be cured with some kind of fuel control, which i do not have.

I told the guy I am doing it for I can start working on the conversion after new years. This gives me some time to research and get all the parts nessassary. I was also thinking I need to figure this boost thing out for sure before I even start because then if I dont come to a solution, I might have to tell him he has to spend more money on other sh!t such as external wastegate etc...

Rob, I shuold take you for a quick spin in my car and let you decided.
I mean it isn't super fast but I'm happy and for a total of $650 to do the whole conversion, I'am very happy.

$600.00 eh? Thats a good deal man! Josh has already spent more than that and still needs more parts! Mabey you should take him for a ride. He is the one I will be doing this for. He wants bling bling too so he is also buying an after market BOV, intake and a bunch of other things he doesnt need to do the job but hey, its his money. I am just the installer. Did you install an oil cooler?

No I haven't installed a oil cooller. (90 style sitting in the basement, just to lazy to install it)
But I do plan on installing it, it might help with the knock issue.

I agree with Tony. It will run 11psi because the spring in the wastegate actuator is set to that amount of pressure. The only way to get a true 7psi is to take an actuator off of another mitsubishi turbo that has it's actuator set at 7psi. I've seen it done before but I don't remember what turbo it was or what it was off of.

Is it possible to take the spring out of the actuator and cut it so there is less spring tention?

NO.
From what Tim said I started to think that a WG from a Dogde Stealth would probally work. I think they run 9 psi stock.
But with the washers, I'm running 7-8psi.
It dosent shoot up instantly like before.

So essentially the washers are pulling the arm out a bit more? I see, so it takes preassure off the spring so it opens earlier!

HMMMM this makes me worried now!!!
I put washers on my big 16g just as you did but I did it for other reasons. My wastegate valve was loose with about 1mm play in it between the exhaust housing so I put the washers in to make the flapper tight against the gate opening. Was it supposed to be loose?

Well,
it shouldn't be to tight (boost climbs to quickly and you run into boost spikes) and not to loose ( to much lag and boost psi peak will be lower).
So in other words I would say yes it should be on a bit on the loose side.
I don't know if it matters if its a 13g or a big 16g but I'm just going with I found on my 13g.

As for the washers, they actually slightly open the flapper in the O2 housing allowing a bit boost to escape and giving more time for the WG actuator to react to quick increases in boost.

Are you running into spikes in boost with the washers installed on your big 16? if not its probally due to that turbo is a bit slower reacting and it allows time to the WG to open.
Problem with the 13g it just spools up to quickly.

Yes, I get boost spikes to 23 psi then it settles to 18/19 psi. I wasnt too worried about it untill now. I hate these actuators! I want to go tubular manifold on my car with a tial 40mm when I have $$$$$ to burn some day.

Anyways, back on topic. Putting washers between the turbo and actuator closes the arm by making the actuator further away from the turbo so it pulls the arm closed, doesnt it? I mean thats what I did to close the gap on my big 16g flapper. The only way to open the flapper would be to get the actuator closer to the turbo, increasing the gap size.

I'll take a look tommorrow on my setup just to confirm the washer thing.

I found this pic. Can anyone tell me why the gate arm has adjustment? Would this be an added feature to control boost? It is off of a 1.8t

The T-3's my brother got for his Camaro have that adjustment on the actuator arms as well. You can adjust the boost slightly with them, but if you just want to decrease boost, why not just put a spring on the WG arm putting a little preload against the WG spring(helping to pull it open). A nice semi long spring that can maintain an even pull over the range of the WG's movement would be ideal... ie you wouldn't want a spring that has a whole lot of tension at the beginning then decreases dramatically as the WG opens. You want it to pull approximately the same tension over the 3/4" of movement that the flapper travels. I have never done it so finding the right spring and the amount of tension will be trial and error.

Simple solution, cut the arm in the middle, thread both ends, and extend arm with something in the middle, effectively making the arm longer.

Your wastegate will be slightly open at cruise/idle making boost come-on slower, but it will trick the wastegate to open at 8psi because of the longer rod, ultimatelly keeping your wastegate one step ahead of your PSI.

When at 5psi, you arm will really be at say 7psi because of the longer arm, hope you can vissual this:).

good stuff!!

On my 14b with a busta boost controller i can lower my boost all the way to 6 i did that a couple of times to prove it to friends.

take boost guages error into account as well

How is this possible at all?! Unless the boost controller has a build-in air compressor to pump the wastegate to open, I really cannot see any way of lowering the stock psi, could you explain how this was done?

That cant be possible.