sr20det overboost in 5th gear only?

[litch]

The facts:

1000 miles on my sr20det swap.

Smoke checked my entire turbo system for leaks... none.

Have a simple T on my turbo line.
http://i1147.photobucket.com/albums/o549/aaronlitchfield/155262_162262110592961_1419990961_n_zps4d915bd4.jp g

Everything is working fine gears 1-4, no overspool, turbo spools perfectly, pulls hard, sits right at 7lbs...

then I shift into 5th and SCARE THE SH*T out of myself when I get on it and I watch the boost gauge go to 17lbs... I lay off the throttle, and downshift into 4th and it boosts back to 7lbs, no higher...


so, I am lost as to the culprit of this problem...

what am I overlooking?

:bash:

[cotbu]

Aside from a controlled boost leak, that should have leaked when you smoke tested. Nothing other than the fact that most internal wastegates that run directly to vacuum tend to open at 7psi. If that's the boost you intend to run, why did you install a bleed type boost controller? Now if you where testing and could adjust that open port with a more restricted line, you'd know you can control boost that way. My only issue is that you're seeing only 7psi in 4th gear really, you should be seeing 14 or 17max till it drops back down to 13~ by redline speculating this is a t25 of course.

[litch]

Aside from a controlled boost leak, that should have leaked when you smoke tested. Nothing other than the fact that most internal wastegates that run directly to vacuum tend to open at 7psi. If that's the boost you intend to run, why did you install a bleed type boost controller? Now if you where testing and could adjust that open port with a more restricted line, you'd know you can control boost that way. My only issue is that you're seeing only 7psi in 4th gear really, you should be seeing 14 or 17max till it drops back down to 13~ by redline speculating this is a t25 of course.



yeah sorry, this is a t25.

I didn't install the bleed type controller, the guy I bought it off of did, his answer was "I am cheap.." which is why I had the turbo lines all smoke tested as soon as I bought the car...to make sure his cheapness didn't = neglect to normal maintenance...

now help me with what you are saying here...

If the wastegate is set to 7lbs, after it spools to that it should open up a valve inside the turbo that allows exhaust gas to bypass the turbo keeping boost @ 7lbs.

What you are saying is that even though the wastegate is set for 7lbs it will boost up to 14-17lbs?

help me here. :ughd:

[cotbu]

If the wastegate is set to 7lbs, after it spools to that it should open up a valve inside the turbo that allows exhaust gas to bypass the turbo keeping boost @ 7lbs.
Yes, might creep a lil or not, but yes
What you are saying is that even though the wastegate is set for 7lbs it will boost up to 14-17lbs?
Yes, with the bleeder boost controller installed, because that's a pretty big leak. All that air should be going to the wastegate and if it's not, boost will rise by the amount being bled. 1. Bleed type Boost Controller

Like all boost controllers, a bleed type controller is installed on the Wastegate vacuum line. It can be installed anywhere on that line, but usually it is best to install the controller as close to the Wastegate as possible and to try and keep that vacuum line as short as possible. The way this controller works is by bleeding off pressure out of the line. The amount of air bled off is what controls the boost. Understanding a bleed type controller is best understood with example. Lets say we have a 10 PSI Wastegate set-up. Under normal conditions the vehicle runs 10 PSI. If we install a bleed type boost controller on the vacuum line heading to the Wastegate that bleeds off 2 PSI of air, then the Turbocharger will now makes 12 PSI. This is because the Wastegate will not open till 10 PSI is reached, and the boost controller is bleeding off 2 psi, so it will take 12 PSI of pressure from the turbo to make 10 PSI to open the Wastegate.

* Pro’s

1. Very solid boost control. No wandering of boost pressure.

2. Controller least susceptible to boost spiking.

*Con’s

1. While it MAY not hinder boost response, it doesn’t help spool response like the other controllers can.

[litch]

Yes, might creep a lil or not, but yes

Yes, with the bleeder boost controller installed, because that's a pretty big leak. All that air should be going to the wastegate and if it's not, boost will rise by the amount being bled. 1. Bleed type Boost Controller

Like all boost controllers, a bleed type controller is installed on the Wastegate vacuum line. It can be installed anywhere on that line, but usually it is best to install the controller as close to the Wastegate as possible and to try and keep that vacuum line as short as possible. The way this controller works is by bleeding off pressure out of the line. The amount of air bled off is what controls the boost. Understanding a bleed type controller is best understood with example. Lets say we have a 10 PSI Wastegate set-up. Under normal conditions the vehicle runs 10 PSI. If we install a bleed type boost controller on the vacuum line heading to the Wastegate that bleeds off 2 PSI of air, then the Turbocharger will now makes 12 PSI. This is because the Wastegate will not open till 10 PSI is reached, and the boost controller is bleeding off 2 psi, so it will take 12 PSI of pressure from the turbo to make 10 PSI to open the Wastegate.

* Pro’s

1. Very solid boost control. No wandering of boost pressure.

2. Controller least susceptible to boost spiking.

*Con’s

1. While it MAY not hinder boost response, it doesn’t help spool response like the other controllers can.


so what you are saying is that I have a leak?

[cotbu]

so what you are saying is that I have a leak?

Smoke checked my entire turbo system for leaks... none.
I wouldn't say that cause, that would make you a liar!

[litch]

I wouldn't say that cause, that would make you a liar!



:tweak: You makin my brain hurt mang, I had it smoke checked the day I bought it, and there was no leak... is it possible that it boosting up to 17lbs popped something and I have a leak now?

[cotbu]

You camera takes shitty pictures, looks like a bleed type boost controller, and you confirmed so that's why I said what i said.:hide:
:lfault:
But after blowing the picture up and sharpening it looks like a screw maybe. so you have to adjust the boost controller by unscrewing it until you set you desired boost in 4th gear and it will spike abit when shifting to 5th, to fix that get a EBC and or Go external gate.
You want 7psi just remove the boost controller altogether.run the line going to the boost controller directly to the wastegate.

[litch]

You camera takes shitty pictures, looks like a bleed type boost controller, and you confirmed so that's why I said what i said.:hide:
:lfault:
But after blowing the picture up and sharpening it looks like a screw maybe. so you have to adjust the boost controller by unscrewing it until you set you desired boost in 4th gear and it will spike abit when shifting to 5th, to fix that get a EBC and or Go external gate.
You want 7psi just remove the boost controller altogether.run the line going to the boost controller directly to the wastegate.


Check, yeah got u, ebc Is what I am gonna do. thanks.