boost creep
Thread Starter
Teching In
Joined: Oct 2016
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Likes: 5
boost creep Hi everyone,
I'm having some issues with boost creep on a 5.3 L33 with a 76mm precision turbo. I'm having trouble controlling boost with a 38mm Tial wastegate. The gate is on the bend of the crossover from non-turbo side of the motor, so it's only venting exhaust from one side of the motor. I do see a lot of people putting their WG's in this spot successfully. It's dumping to atmosphere through a short straight tube. With a 8.7 lb spring I'm at 11 lbs in 1st gear, 12 lbs in 2nd gear and creeping to almost 14lbs in 3rd on a 1/4 mile run. I can definitely hear the gate opening. I;m not currently using any boost control, just running spring pressure.
Any suggestions on a best course of action? I'm honestly just looking for 15 psi steady across the board. Is it as simple as just a larger WG? Or do I have to re position it? I know 15 lbs should be easier to control than 8.7 lbs but it seems I'm not even close right now. I did try a 11.6 lb spring setup in the WG previously and had similar creep up top.
I'm having some issues with boost creep on a 5.3 L33 with a 76mm precision turbo. I'm having trouble controlling boost with a 38mm Tial wastegate. The gate is on the bend of the crossover from non-turbo side of the motor, so it's only venting exhaust from one side of the motor. I do see a lot of people putting their WG's in this spot successfully. It's dumping to atmosphere through a short straight tube. With a 8.7 lb spring I'm at 11 lbs in 1st gear, 12 lbs in 2nd gear and creeping to almost 14lbs in 3rd on a 1/4 mile run. I can definitely hear the gate opening. I;m not currently using any boost control, just running spring pressure.
Any suggestions on a best course of action? I'm honestly just looking for 15 psi steady across the board. Is it as simple as just a larger WG? Or do I have to re position it? I know 15 lbs should be easier to control than 8.7 lbs but it seems I'm not even close right now. I did try a 11.6 lb spring setup in the WG previously and had similar creep up top.
Thread Starter
Teching In
Joined: Oct 2016
Posts: 30
Likes: 5
i guess my other question would be - considering my current boost, could I just put in a stiffer set of springs in the WG to get to 15lbs consistently since it's only creeping to just under 14 lbs now? I don't fully understand if WG's open progressively or more like an on/off switch? It seems to me like it's either open or closed but I may be wrong....
Single 38mm is a bit on the small side for a 5.3 if your trying to run lower boost numbers. You should be running dual 38mm or a single 44mm at minimum. Stepping up to a 50 or 60mm wouldn’t be needed but would be worth it on bigger setups. I bet adding another 38mm to the other side would help. Or block off the 38 and run a 44mm where the 2sides join before the turbo. I have a 5.3 with a billet 78/75 and I can run 6psi no problem with a 60mm HKS clone which has a smaller 2” outlet even tho the inlet is 60mm.
TECH Enthusiast
Joined: Feb 2020
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Sounds like a good traction control strategy the way it is now - lol
I think if you raise the spring pressure you're going to just raise all those numbers -over 15 lbs in 3rd
I second the relocation of current gate or add a second one
I have a single 44mm vs gate on a 6L with no problem controlling boost down to 5 psi (haven't tried lower)
I think if you raise the spring pressure you're going to just raise all those numbers -over 15 lbs in 3rd
I second the relocation of current gate or add a second one
I have a single 44mm vs gate on a 6L with no problem controlling boost down to 5 psi (haven't tried lower)
Sounds like a good traction control strategy the way it is now - lol
I think if you raise the spring pressure you're going to just raise all those numbers -over 15 lbs in 3rd
I second the relocation of current gate or add a second one
I have a single 44mm vs gate on a 6L with no problem controlling boost down to 5 psi (haven't tried lower)
I think if you raise the spring pressure you're going to just raise all those numbers -over 15 lbs in 3rd
I second the relocation of current gate or add a second one
I have a single 44mm vs gate on a 6L with no problem controlling boost down to 5 psi (haven't tried lower)
TECH Fanatic
Joined: Dec 2019
Posts: 1,129
Likes: 478
Hi everyone,
I'm having some issues with boost creep on a 5.3 L33 with a 76mm precision turbo. I'm having trouble controlling boost with a 38mm Tial wastegate. The gate is on the bend of the crossover from non-turbo side of the motor, so it's only venting exhaust from one side of the motor. I do see a lot of people putting their WG's in this spot successfully. It's dumping to atmosphere through a short straight tube. With a 8.7 lb spring I'm at 11 lbs in 1st gear, 12 lbs in 2nd gear and creeping to almost 14lbs in 3rd on a 1/4 mile run. I can definitely hear the gate opening. I;m not currently using any boost control, just running spring pressure.
Any suggestions on a best course of action? I'm honestly just looking for 15 psi steady across the board. Is it as simple as just a larger WG? Or do I have to re position it? I know 15 lbs should be easier to control than 8.7 lbs but it seems I'm not even close right now. I did try a 11.6 lb spring setup in the WG previously and had similar creep up top.
I'm having some issues with boost creep on a 5.3 L33 with a 76mm precision turbo. I'm having trouble controlling boost with a 38mm Tial wastegate. The gate is on the bend of the crossover from non-turbo side of the motor, so it's only venting exhaust from one side of the motor. I do see a lot of people putting their WG's in this spot successfully. It's dumping to atmosphere through a short straight tube. With a 8.7 lb spring I'm at 11 lbs in 1st gear, 12 lbs in 2nd gear and creeping to almost 14lbs in 3rd on a 1/4 mile run. I can definitely hear the gate opening. I;m not currently using any boost control, just running spring pressure.
Any suggestions on a best course of action? I'm honestly just looking for 15 psi steady across the board. Is it as simple as just a larger WG? Or do I have to re position it? I know 15 lbs should be easier to control than 8.7 lbs but it seems I'm not even close right now. I did try a 11.6 lb spring setup in the WG previously and had similar creep up top.
You'll always have trouble controlling boost there. You can upgrade to a larger gate, but it won't be as simple as clamping it on.
A larger fitting will need welded onto the piping if you want it to actually make any difference.
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9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
Please tune your car to 100 psi, make it creep to that number, and report back. Not everyone has the fuel system, etc. to tune for higher boost levels. Simply tuning for all higher boost is a bandaid, not a solution if you want to run less boost.
9 Second Club
Joined: Nov 2003
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From: Norn Iron
his creep of 14psi, isnt quite 100psi though.
TECH Apprentice
Joined: Nov 2016
Posts: 371
Likes: 18
From: switzerland
i think turbo guys get too much obsessed with boost creep for some reason. for centri guys its how it works. there sure is a benefit of having less boost at toque peak than at redline and usually you dont get full boost with a well mached turbo much before torque peak anyway, so you dont loose anything there.
the same for the gears. one of the benefit of turbos is less boost in lower gears.
the same for the gears. one of the benefit of turbos is less boost in lower gears.
TECH Fanatic
Joined: Dec 2019
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i think turbo guys get too much obsessed with boost creep for some reason. for centri guys its how it works. there sure is a benefit of having less boost at toque peak than at redline and usually you dont get full boost with a well mached turbo much before torque peak anyway, so you dont loose anything there.
For a Centri-blower, you size the pulley around how much boost you want, and boost increases to that point with almost zero possibility of excess boost. Its expected and controlled.
With turbo boost creep, you size the spring around how much boost you want, and then you end up with excess boost that you had no way of expecting and zero way of controlling.
Its uncontrolled boost. No amount of money spent on a boost controller will prevent or control it, the root cause itself must be fixed.
And not getting peak boost before torque peak with a well matched turbo? You've never driven a well-matched turbo V8 combo I take it? My Nova made 20 PSI at 3600 RPM.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
i think turbo guys get too much obsessed with boost creep for some reason. for centri guys its how it works. there sure is a benefit of having less boost at toque peak than at redline and usually you dont get full boost with a well mached turbo much before torque peak anyway, so you dont loose anything there.
the same for the gears. one of the benefit of turbos is less boost in lower gears.
the same for the gears. one of the benefit of turbos is less boost in lower gears.
And you would never have peak torque at a lower boost....higher boost will almost always yield more torque...that's the whole point of boost !
And there is nothing set in stone to say you will have less boost in lower gears vs higher gears. With good boost control on a well matched setup, you can have whatever boost you want in any gear.
TECH Apprentice
Joined: Nov 2016
Posts: 371
Likes: 18
From: switzerland
why would boost creep be "ucontrolled" boost? because your controller doesnt control it? its as inherently build into the system as on a centri. i have driven my turbo car for many years with intentional boost creep i got by limiting wastegate valve travel.
and if you got full boost at 3600 your choking the engine at 7000 for sure. (unless we were talking an electronically contolled variable turbo as on the late model cars where you get flat torque from 2000 on.)
op, if you get 11 psi in first and "creep" up to 14 psi in third, i consider that an ideal situation. think about it. (i had my car set up with about 5 psi of "creep".)
and if you got full boost at 3600 your choking the engine at 7000 for sure. (unless we were talking an electronically contolled variable turbo as on the late model cars where you get flat torque from 2000 on.)
op, if you get 11 psi in first and "creep" up to 14 psi in third, i consider that an ideal situation. think about it. (i had my car set up with about 5 psi of "creep".)
Last edited by Dian; Feb 25, 2020 at 10:22 PM.