should a stock t-25 turbo be boosting past 20lbs?

[GofaST4life]

Ive tried searching but i couldnt come up with anything that really answered my questions. I still new at this (DSM), but im learning quickly and im loving it more and more...

Here's my isssue, im running pretty much a stock GST at the moment, stock turbo, exhaust, everything, im collecting all the parts and doing things on my own time...but anyway, back to my issue, i do have an after market boost gauge that came already installed in the car...here's where i think something is not right, should a stock t-25 turbo be boosting past 20lbs??? Wouldn't it be acting more like a heating pump? hahahaha I have a turbo temp gauge as well, how hot should my turbo be getting??? and isnt 20 plus lbs on a stock turbo DANGEROUS!?!?!

Ive been reading enough on this site and others to be concerned.

This is the only turbo charged car ive driven, so i cant really compare to like another car with less boost to see if there is like a difference or what not, but the car picks up its balls and f*cking goes when i want it to...im just trying to give as much info so you guys who know these cars well can help out a new comer...

Questions
1. Should a stock turbo be boosting that much?

2. Is there anyway i can possibly turn the turbo down, like with a manual boost controller or something of the sort?


-Aaron

 

[ROOKIE1]

1. no
2.yes

 

[qiklitltsi]

20psi on a t25 is past its peak efficenciy so its not doing any good and actully can damadge the turbo.
I beleive you should check your waste gate and vacume lines going to your waste gate, it sounds like your waste gate isnt working or doesnt have a vacume line connected to it.

 

[91 Turbo Mitsu]

The first thing that I would do is make sure the boost gauge was installed correctly. Then start checking other things like the wastegate and vacuum lines.

 

[GofaST4life]

ill check that out, hopefully i dont get confused with all that...

 

[kenamond]

ill check that out, hopefully i dont get confused with all that...

The T25 compressor housing (silver housing on the passenger side) has a nipple on it.
The bronze-colored can bolted to the compressor housing (the wastegate actuator or WGA) also has a nipple on it. There are vaccuum lines and T fittings and the like that go to your stock boost control solenoid or BCS (assuming you don't have an aftermarket manual boost controller or MBC).

If you pull the vaccuum lines off of the two nipples I described, cap the hoses off, and run a single vaccuum line from one nipple to the other, you should get around 10psi boost. Capping the lines you took off will avoid unmetered air from getting sucked into the intake when you do this test.

If you still boost to 20psi, and you're confident that the boost gauge is working properly, the wastegate isn't working properly.

Some things that you should read up on are:
Boost gauge install (here is a link)
How to test the wastegate (actuator, actuator arm, lever on the turbine housing)
How to make a boost leak tester
How to do a boost leak test

All of those things are good to know and aren't a waste of time to research. And yes, there's a whole lot more. But first thing's first.

EDIT: And so you know, when about 10psi is applied to the WGA, the arm coming out the opposite side from the nipple will extend. This turns a lever on the turbine housing (other end of the turbo on the driver's side). The lever operates an internal wastegate inside the turbine housing. The internal wastegate is just an alternate passage for the exhaust gasses. When the lever turns on the housing, a flapper inside the housing opens up a hole into that alternate passage. This lets some of the exhaust coming from the exhaust manifold bypass the turbine wheel, thus limiting the amount of boost you get. So getting 20psi on a T25 (if the boost gauge is working) is probably due to a problem with the wastegate system. Now the BCS or an MBC basically hide boost pressure from the WGA so that when the WGA finally sees 10psi, the actual boost pressure could be much higher depending on how much of the actual boost pressure has been "hidden" by the boost controller. So by putting a vaccuum line between the compressor outlet nipple and the WGA, you're showing the WGA the actual boost (nothing is hidden), so your boost will be limited to about 10psi. This is just a quick way to eliminate the boost controller from the situation. If this direct vaccuum line setup results in you getting 10psi of boost, then something's messed up with your boost controller or their vaccuum lines. If you still get 20psi, then something's messed up with the wastegate system.

 

[GofaST4life]

your knowledge overwhelms me...literally...thank you!!

 

[G9S6T]

Just for the sake of your motor and turbo dont go into boost until you find your problem. I had this same problem when I changed my type-rs for a type-s. I was spiking like 22psi in my t-25. Changed the bov and back to 15 solid.

 

[sd_ff22]

everything kenamond said +1

that guy is like god, only for our cars!

 

[thekellbeast]

You'll kill the turbo pushing it that hard. Mine died after about a month of 17-18psi.

 

[95burgundyesi]

You'll kill the turbo pushing it that hard. Mine died after about a month of 17-18psi.

It exploded!

 

[laserspeeddemon]

The T25 compressor housing (silver housing on the passenger side) has a nipple on it.
The bronze-colored can bolted to the compressor housing (the wastegate actuator or WGA) also has a nipple on it. There are vaccuum lines and T fittings and the like that go to your stock boost control solenoid or BCS (assuming you don't have an aftermarket manual boost controller or MBC).

If you pull the vaccuum lines off of the two nipples I described, cap the hoses off, and run a single vaccuum line from one nipple to the other, you should get around 10psi boost. Capping the lines you took off will avoid unmetered air from getting sucked into the intake when you do this test.

If you still boost to 20psi, and you're confident that the boost gauge is working properly, the wastegate isn't working properly.

Some things that you should read up on are:
Boost gauge install (here is a link)
How to test the wastegate (actuator, actuator arm, lever on the turbine housing)
How to make a boost leak tester
How to do a boost leak test

All of those things are good to know and aren't a waste of time to research. And yes, there's a whole lot more. But first thing's first.

EDIT: And so you know, when about 10psi is applied to the WGA, the arm coming out the opposite side from the nipple will extend. This turns a lever on the turbine housing (other end of the turbo on the driver's side). The lever operates an internal wastegate inside the turbine housing. The internal wastegate is just an alternate passage for the exhaust gasses. When the lever turns on the housing, a flapper inside the housing opens up a hole into that alternate passage. This lets some of the exhaust coming from the exhaust manifold bypass the turbine wheel, thus limiting the amount of boost you get. So getting 20psi on a T25 (if the boost gauge is working) is probably due to a problem with the wastegate system. Now the BCS or an MBC basically hide boost pressure from the WGA so that when the WGA finally sees 10psi, the actual boost pressure could be much higher depending on how much of the actual boost pressure has been "hidden" by the boost controller. So by putting a vaccuum line between the compressor outlet nipple and the WGA, you're showing the WGA the actual boost (nothing is hidden), so your boost will be limited to about 10psi. This is just a quick way to eliminate the boost controller from the situation. If this direct vaccuum line setup results in you getting 10psi of boost, then something's messed up with your boost controller or their vaccuum lines. If you still get 20psi, then something's messed up with the wastegate system.

You beat me to eat, but you posted at 2 AM. I roam the tech sections when I get a case of insomnia myself.

 

[thekellbeast]

It exploded!

Damn straight it did. That puny little thing grenaded itself.

You won't make any more power pushing a t-25 up in that range anyways. Have your t-25 rebuilt into a t-28, or get a real turbo.

 

[92dsmtalon]

Damn straight it did. That puny little thing grenaded itself.

You won't make any more power pushing a t-25 up in that range anyways. Have your t-25 rebuilt into a t-28, or get a real turbo.

I like the idea of a real turbo, go with a 16g or something. But anyway, when I put on my manual boost controller, mine was boosting at 21psi, deffinatly not good, haha. I of course turned it back down, and I am running 16psi. Although, I need to adjust my BOV because sometimes it still spikes to around 18-20psi.

 

[DSMunknown]

Click here and read. In case you're wondering, I've got plenty more photos for you to gaze over in case you still don't know how to properly hook up an MBC. By the way, Aaron, you've already proven your Newbie status here. I don't want to see you starting a thread in the Site Feedback section and bitching about becoming a Proven member in a couple weeks.

 

[GofaST4life]

im not one to bi***, but thankx for the info, esp in the first link...

 

[res7bequ]

Click here and read. In case you're wondering, I've got plenty more photos for you to gaze over in case you still don't know how to properly hook up an MBC. By the way, Aaron, you've already proven your Newbie status here. I don't want to see you starting a thread in the Site Feedback section and bitching about becoming a Proven member in a couple weeks.

triple check the boost controller because if its hooked up wrong you can be super boosting and blow your head gasket (like i did)

 

[gunny11218]

all those G's have gotta feel good though, and yes its extremely dangerous. get a 14b thats what i have

 

[kenamond]

your knowledge overwhelms me...literally...thank you!!

Go look under your hood with what I said in mind (you may want to go back to the computer after the first look and re-read).

If you still don't understand something, just ask (or search...but I'm a sucker). I'm a freak who likes teaching - and learning. I won't mind. If I can't answer your question(s) or if I answer wrong, you'll most likely get the right answer from someone else (and I'll get embarrassed but learn something at the same time). It's a win-win situation for everyone.

 

[G9S6T]

Go look under your hood with what I said in mind (you may want to go back to the computer after the first look and re-read).

If you still don't understand something, just ask (or search...but I'm a sucker). I'm a freak who likes teaching - and learning. I won't mind. If I can't answer your question(s) or if I answer wrong, you'll most likely get the right answer from someone else (and I'll get embarrassed but learn something at the same time). It's a win-win situation for everyone.

Amen...

 

[GofaST4life]

what temp should a turbo normally be running, both under boost and when non-boosting??

 

[DSMunknown]

what temp should a turbo normally be running, both under boost and when non-boosting??

Really hot. Any particular reason you asked?

 

[GofaST4life]

just wondering really, i have the temp gauge, though id ask just to see if maybe it was running hotter than normal, or something...

 

[wret]

We don't normally check the temperature of the turbo, but there is such a thing as an exhaust gas temperature gauge or EGT. 1600° is about the max for EGTs.

Don't let these guys make fun about the size of your turbo. There's a LOT of fun to be had with the fast spooling T25.

 

[TiradoCC]

Can you get a pic of the turbo with the intake off?....reason I ask is because my friend bought a talon tsi not too long ago and it was also "stock". He was boosting at around 15-20 psi also and holding it to redline, which I thought was very weird for a t25. So I checked the fins of the "t25" and sure enough it was a t28