Compound turbo tuning

[Ridin'GMC]

So as the title says, need some tips to get me dialed in on my LBZ. I've done countless research over the web and not much info to get me dialed in. Mostly related to vgt tables and map/boost settings. So far I've taken small changes in the tuning as I've progressed over each tunes I've done and each has made improvements. Trying to clean up the smoke at low end.

Any help would be appreciated, it does seem at this point most people prefer to keep it quiet and talk over DM.

Here's my dilemma, I've already adjusted the MAF and it's reading 41-42 g/s at idle when warmed up but 48-50 when cold, I'm assuming this is due to the vane setting in the cold setup. At full boost, it'll trip a p0108 when it's hitting 38 psi and the vanes back off to reduce boost to prevent over boosting, I'm not sure if I should set the boost setting higher in the desired boost tables, l will be getting a boost gauge for the atmospheric turbo to read what it is pushing, I have my total boost gauge tapped in the y bridge. Turbo setup is 480 billet race cover over JZ 63mm vgt valley turbo. Stock fueling for now, but does have an exergy sportsman cp3. No low rail pressure code, holds 24-25k at wot. I've been tuning my LBZ since 2011 and this is my first compound turbo tuning, it's a different ball game to get it dialed in and taking small steps not to hurt anything.

 

[2004LB7]

For your smoke at low boost, log your air per cylinder and then adjust the fuel mixture limit table

Using the scan tool, you can log the actual boost and build a new table for that. Then actual and expected should more closely match

You can use this same process but for the boost table

Adjusting Vane Position | Fish Tuning

NOTE: This information is for learning purposes only. We do not take responsibility for anything that happens to your vehicle as a result. Please use at your own risk!Adjusting Vane Position on your DuramaxThanks to Tyler at Punisher PerformanceSo you’ve increased your desired boost pressure...

www.fishtuning.com

 

[Ridin'GMC]

For your smoke at low boost, log your air per cylinder and then adjust the fuel mixture limit table

Using the scan tool, you can log the actual boost and build a new table for that. Then actual and expected should more closely match

You can use this same process but for the boost table

Adjusting Vane Position | Fish Tuning

NOTE: This information is for learning purposes only. We do not take responsibility for anything that happens to your vehicle as a result. Please use at your own risk!Adjusting Vane Position on your DuramaxThanks to Tyler at Punisher PerformanceSo you’ve increased your desired boost pressure...

www.fishtuning.com

Thanks. Does this correct the issue for popping an over boost code? As I've read, I should be pushing 55-60 with my setup, can't get over 40. That's when it pops the code and backs off the boost to low 30s. I have my desired set around 40, wasn't sure if I can raise it higher without hurting the valley turbo, wasn't sure if the atmospheric turbo pressure is added to the combination of the valley charger pressure to not over speed/over boost the valley charger.

 

[2004LB7]

The valley turbo boost that it sees is the difference between the incoming pressure and outgoing pressure. So if your large turbo is pushing 30 psi into it and the valley turbo bumps that up to 60 psi then the valley turbo is only doing 30 not 60 psi

If you have the table set to where it should be then it will prevent the codes and limp

 

[Bdsankey]

The valley turbo boost that it sees is the difference between the incoming pressure and outgoing pressure. So if your large turbo is pushing 30 psi into it and the valley turbo bumps that up to 60 psi then the valley turbo is only doing 30 not 60 psi

If you have the table set to where it should be then it will prevent the codes and limp

Correct. The target/desired should be actual not just the valley turbo's contribution tho since it's read off the MAP sensor.

 

[JoshH]

It's actually a little more complicated than that. If you look at a turbo map, you will see there are no boost pressures listed. They list total airflow and pressure ratio. You have to compare the total pressure coming into the turbo and relate that to the total pressure coming out. As a general rule of thumb, you can shoot for double whatever the atmosphere turbo is doing. If the atmo is doing 30 psig, then generally 60 psig from the valley turbo is safe. That said, you will have to disable overboost codes because you will max out the stock map sensor. You will also want to use the minimum vane position table to control total boost or the vanes will open up all the way in an effort to keep boost under control. It helps to have 2 boost gauges (1 between stages and 1 in the y-bridge) to get the tuning dialed in.

 

[TheBac]

Because of Josh's explanation, I've sticky'd this thread so we don't lose that (or any other) info.