Overboosting, can't figure out why
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On The Tree
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Overboosting, can't figure out why Hi, I just got my turbo set up installed on mt 03 silverado with an LQ9 6.0l, 212/218 cam and it wants to boost much higher then desired. Its an STS kit with a 61 turbo, .80 A/R and has 38mm waist gate. I have everything hooked up correct and with the 5 psi wg spring it will hit 11 psi at 1/2 throttle in first gear. The spring is black with red on one end. It will even hit 2 psi revving it in neutral. I tried two different boost gauges and they read the same.
I'm using a soft spring from a stock 4l60e in the waist gate right now and it will go 6psi in 1st gear and hit 8psi in 2nd and seems to still be climbing up. I took the waist gate apart and everything looks fine, I also cleaned the shaft up. Any ideas ?
I'm using a soft spring from a stock 4l60e in the waist gate right now and it will go 6psi in 1st gear and hit 8psi in 2nd and seems to still be climbing up. I took the waist gate apart and everything looks fine, I also cleaned the shaft up. Any ideas ?
If I think I understand your system correctly, then you should be able to just disconnect your vacuum/boost line to the WG and it should give you a relatively low boost.
If you have it setup as boost assisted, then I'm guessing you have a boost controller in somewhere in that line?
If you have it setup as boost assisted, then I'm guessing you have a boost controller in somewhere in that line?
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On The Tree
Joined: Aug 2010
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Here are a couple picture from under the truck. I'm lost to as of why the boost is so high. I just got back from taking it for a run, its 87F ambient right now so boost came up slower then yesterday at 60F but once in 2nd gear it doesn't seem to quit climbing.
10 Second Club
Joined: Jul 2011
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From: Seattle
I have to say I think your WG is too small especially considering it is mounted at a 90* angle to the exhaust flow making it not optimal for controlling low boost. That coupled with a small turbo and a big engine = overboost
fix the position of the WG or put a bigger one on.
Thread Starter
On The Tree
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The wg valve has to move towards the spring to open.
I was wondering if the 61 is a little small for a 6.0l with a small cam ? I could put the wg where the pipe goes up 90* to the turbo so the exhaust has a straight shot at it right before the turbo ?
If I remember right when I had the wg off and looking into the exhaust, the welded on wg flange wasn't centered very well over the drilled hole, at least 1/8 to 1/4in off center. I will port that to match and see what happens.
I have to say I'm not too impressed with STS's kit.... The cold pipe going back up is all steel piping (holds in the heat) The hot side 90* going up to the turbo isn't even mandrel bent. My intake temps cruising today were 127F and a 4.5 second wot pull brought them up to 162F.. Hopefully the e85 holds it own.
I was wondering if the 61 is a little small for a 6.0l with a small cam ? I could put the wg where the pipe goes up 90* to the turbo so the exhaust has a straight shot at it right before the turbo ?
If I remember right when I had the wg off and looking into the exhaust, the welded on wg flange wasn't centered very well over the drilled hole, at least 1/8 to 1/4in off center. I will port that to match and see what happens.
I have to say I'm not too impressed with STS's kit.... The cold pipe going back up is all steel piping (holds in the heat) The hot side 90* going up to the turbo isn't even mandrel bent. My intake temps cruising today were 127F and a 4.5 second wot pull brought them up to 162F.. Hopefully the e85 holds it own.
Looks like it is hooked up to pop WG open rather early then - so I don't think it is the connection.
If you feel like troublshooting the WG, the next step is to go get a cheapy air regulator from home depot. Grab an air compressor and using the air regulator in series with a hose connected to the lower point of the WG (where you have it connected) determine what pressure you need to actuate the waste gate open while watching through the discharge - careful not to blow the diaphram.
If it is much higher than 5 psi then you know it is the waste gate. If it is right around 5 psi, then you know you may be looking at larger system design issues (WG too small etc...)
If it was boost creep, I would think you could hear the open waste gate rather clearly.
If you feel like troublshooting the WG, the next step is to go get a cheapy air regulator from home depot. Grab an air compressor and using the air regulator in series with a hose connected to the lower point of the WG (where you have it connected) determine what pressure you need to actuate the waste gate open while watching through the discharge - careful not to blow the diaphram.
If it is much higher than 5 psi then you know it is the waste gate. If it is right around 5 psi, then you know you may be looking at larger system design issues (WG too small etc...)
If it was boost creep, I would think you could hear the open waste gate rather clearly.
