08-10 SS Turbocharged General Discussion Discuss the 2008 - 2009 Chevy Cobalt SS Turbocharged. On sale since the second quarter of 2008.

Bnr k04-gt28

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Old 01-19-2011, 05:00 PM
  #651  
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Thanks man!
Old 01-19-2011, 05:28 PM
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anyupdates? I am sure tglems is not the only one with this.
Old 01-19-2011, 05:33 PM
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We have boost! So it was a blessing in disguise that this happened because then I was able to find and fix the boost leaks with the MAF and tMAP sensors, but this is what happened...
The wastegate solenoid

looks like a 'T'. One line goes to the top of the wastegate can, the far side line goes up somewhere near the intake manifold/above the engine (I forget), and the third line used to connect somewhere on the stock turbo. With the GT2871 that third line (the one right next to the one going to the top side of the wastegate can) isn't connected to anything so I capped it instead of having it open to atmosphere. Well, for some reason that made me lose boost. After messing around with a bunch of stuff I uncapped it and now have boost again. Maybe someone can explain to me why, but all I know is that for some reason it works. To me it looks like the wastegate can is open to atmosphere, which doesn't make sense, but oh well.

Thanks for all the suggestions about things to look for. Like I say, it was probably a good thing since I did find that I needed to tighten the MAF and close those holes near the tMAP.
Old 01-19-2011, 05:38 PM
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wow well ur right at lest u fixed everything....I hope someone knows...are u going to be doing some tuning tonight?
Old 01-19-2011, 05:41 PM
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Nice! Glad you got it all sorted out now!
Old 01-19-2011, 06:18 PM
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yes this is very true you need to leave that third line on the boost solenoid OPEN. I found that one out the hard way too lol
Old 01-19-2011, 06:26 PM
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Originally Posted by tglems
We have boost! So it was a blessing in disguise that this happened because then I was able to find and fix the boost leaks with the MAF and tMAP sensors, but this is what happened...
The wastegate solenoid

looks like a 'T'. One line goes to the top of the wastegate can, the far side line goes up somewhere near the intake manifold/above the engine (I forget), and the third line used to connect somewhere on the stock turbo. With the GT2871 that third line (the one right next to the one going to the top side of the wastegate can) isn't connected to anything so I capped it instead of having it open to atmosphere. Well, for some reason that made me lose boost. After messing around with a bunch of stuff I uncapped it and now have boost again. Maybe someone can explain to me why, but all I know is that for some reason it works. To me it looks like the wastegate can is open to atmosphere, which doesn't make sense, but oh well.

Thanks for all the suggestions about things to look for. Like I say, it was probably a good thing since I did find that I needed to tighten the MAF and close those holes near the tMAP.
That solenoid is used to divert boost away from the wastegate actuator. When the boost control duty cycle is high, it means that more boost is coming out of that fitting that you are talking about, and less is going to the actuator. It is basically bleeding boost off so that the actuator does not open the gate as soon. When you plug off that line, the boost can not be diverted properly. That would definitely cause lower boost levels.
Old 01-19-2011, 07:37 PM
  #658  
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Originally Posted by tglems
We have boost! So it was a blessing in disguise that this happened because then I was able to find and fix the boost leaks with the MAF and tMAP sensors, but this is what happened...
The wastegate solenoid

looks like a 'T'. One line goes to the top of the wastegate can, the far side line goes up somewhere near the intake manifold/above the engine (I forget), and the third line used to connect somewhere on the stock turbo. With the GT2871 that third line (the one right next to the one going to the top side of the wastegate can) isn't connected to anything so I capped it instead of having it open to atmosphere. Well, for some reason that made me lose boost. After messing around with a bunch of stuff I uncapped it and now have boost again. Maybe someone can explain to me why, but all I know is that for some reason it works. To me it looks like the wastegate can is open to atmosphere, which doesn't make sense, but oh well.

Thanks for all the suggestions about things to look for. Like I say, it was probably a good thing since I did find that I needed to tighten the MAF and close those holes near the tMAP.
You turd I told you that had to stay open when the turbo was off haha.I'm glad you found it though.I even explained to you why it had to stay open.I feel invisible and ignored at times lol
Old 01-19-2011, 08:01 PM
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Originally Posted by 1LowLS
You turd I told you that had to stay open when the turbo was off haha.I'm glad you found it though.I even explained to you why it had to stay open.I feel invisible and ignored at times lol
lol I remember you telling him this. Glad its figured out
Old 01-19-2011, 08:21 PM
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Originally Posted by 1LowLS
You turd I told you that had to stay open when the turbo was off haha.I'm glad you found it though.I even explained to you why it had to stay open.I feel invisible and ignored at times lol
i remember this too lol
Old 01-19-2011, 08:48 PM
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well i getting tuned slowly i at 24 psi and it holds good till redline will see what is next then to hp and trifecta
Old 01-19-2011, 08:53 PM
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^^^^When does boost onset start and at what rpm are you make 24 psi?
Old 01-19-2011, 08:53 PM
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I just found this thread and don't want to try reading through the whole thing with my iPod. Is this turbo upgrade ready to go and do you need a BOV? How much do they cost?
Old 01-19-2011, 09:15 PM
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BNR website reveals all...

BNR Supercars - Bryan Nickell's Rotary Supercars - Solstice, Sky, Cobalt SS, HHR SS
Old 01-19-2011, 11:58 PM
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Originally Posted by HHRSSouth
^^^^When does boost onset start and at what rpm are you make 24 psi?
will update tomorrow when i drive to work.
Old 01-20-2011, 02:21 AM
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Originally Posted by 1LowLS
You turd I told you that had to stay open when the turbo was off haha.I'm glad you found it though.I even explained to you why it had to stay open.I feel invisible and ignored at times lol
Man, I wish somebody had told me this...

Originally Posted by FF_ace
lol I remember you telling him this. Glad its figured out
Anybody...

Originally Posted by BlackBeast!
i remember this too lol
Anybody at all...

Okay but seriously...I remember about the line coming from the valve cover and that has to stay open, getting a breather filter, etc, but not this other line.
Old 01-20-2011, 08:42 AM
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so the line going from the valve cover to the stock turbo is left open now? And the line that connects from the valve cover to the intake still is in tact right? there are 2 lines and just trying to get it straight.
Old 01-20-2011, 08:56 AM
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Originally Posted by HHRSSouth
^^^^When does boost onset start and at what rpm are you make 24 psi?
Well looks like i hit full boost around 3200 to 3500. I think my wastegate needs to be adjusted. It was hitting full boost a little sooner before i get retuned.
Old 01-20-2011, 09:07 AM
  #669  
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Originally Posted by turbo_chevy_cobalt
Well looks like i hit full boost around 3200 to 3500. I think my wastegate needs to be adjusted. It was hitting full boost a little sooner before i get retuned.
Vince might have lowered the WG desired DC percentage in the lower RPMs to keep the boost from spiking if it is boosting a little later now that it got retuned. Your WG rod nuts (LOL) could have come loose as well.
Old 01-20-2011, 09:56 AM
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After doing some research on the 2860 and then comparing it to our stock turbo I'm a bit confused.

People have seen 35 lb/min on the stock K04, the GT2860 is rated at 35 lb/min. But here is whats confusing, the compressor is bigger on the GT2860 and the turbine is slightly bigger.

So in theory in the GT2860 should make more power all the way through the rpm band on our cars then the K04 since the turbine and compressor are bigger?

So how can our k04 make 35 lb/min witha smaller turbine and compressor and then the 2860 make 35 lb/min witha bigger turbine and compressor? Are people pushing the k04 out of its effeciencly range to get 35 lbs/min?

So in theory you should be able to push the GT2860 above 35 lbs/min on our cars with good tuning?
Old 01-20-2011, 10:02 AM
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Originally Posted by Terminator2
Vince might have lowered the WG desired DC percentage in the lower RPMs to keep the boost from spiking if it is boosting a little later now that it got retuned. Your WG rod nuts (LOL) could have come loose as well.
If it senses an underboost condition it will still increase to the 95% anyway. Just had this talk with Vince yesterday about why I asked for 75% MAX WGDC and still saw 95% at times..On the Subaru's and some other cars you can literally set the MAX point and it will never go over it, I thought this would work the same but Vince tells me otherwise.
Old 01-20-2011, 10:49 AM
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Originally Posted by HHRSSouth
After doing some research on the 2860 and then comparing it to our stock turbo I'm a bit confused.

People have seen 35 lb/min on the stock K04, the GT2860 is rated at 35 lb/min. But here is whats confusing, the compressor is bigger on the GT2860 and the turbine is slightly bigger.

So in theory in the GT2860 should make more power all the way through the rpm band on our cars then the K04 since the turbine and compressor are bigger?

So how can our k04 make 35 lb/min witha smaller turbine and compressor and then the 2860 make 35 lb/min witha bigger turbine and compressor? Are people pushing the k04 out of its effeciencly range to get 35 lbs/min?

So in theory you should be able to push the GT2860 above 35 lbs/min on our cars with good tuning?
I've never seen greater than 31.5 VE lb/min on the stock K04 no matter what psi it pushes. One of the other tuners can add their experiences.

Skewing the MAF airflow or correction for ethanol blends will increase the MAF lb/min in error.
Old 01-20-2011, 10:57 AM
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i was seeing 38-39 out of tglems car last night while doing some data logging for byt
Old 01-20-2011, 10:59 AM
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At my altitude the bast I have logged with the stock K04 is 30.5Lb/min VE.. I imagine I might be able to squeeze out 31lb/min when I get up to phoenix to to some runs next weekend.
Old 01-20-2011, 11:00 AM
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Originally Posted by FF_ace
i was seeing 38-39 out of tglems car last night while doing some data logging for byt
Mike was seeing 35lb/min VE on his 2871 and making 422WHP, so I imagine thats pretty good at 38-39


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