need a little help with boost issue
Thread Starter
On The Tree
Joined: Jan 2015
Posts: 123
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all I'm wanting to do right now is run this little 9lbs and be able to keep that 9lbs all the way to 6500. I was hoping I could accomplish this with just spring pressure but from what you guys are telling me I need a controller on this thing, likely due to back presdure. so now I wondering how all the factory setups keep their boost until redline without a controller
Last edited by boostedxs; Jun 24, 2017 at 07:27 AM.
all I'm wanting to do right now is run this little 9lbs and be able to keep that 9lbs all the way to 6500. I was hoping I could accomplish this with just spring pressure but from what you guys are telling me I need a controller on this thing, likely due to back presdure. so now I wondering how all the factory setups keep their boost until redline without a controller
TECH Apprentice
Joined: Nov 2016
Posts: 371
Likes: 18
From: switzerland
"so now I wondering how all the factory setups keep their boost until redline without a controller"
they dont. that used to be a very typical situation on turboed cars. boost would typically drop from 0.8 bar to 0.5 bar at redline. thats why they were so easy to tune. if you took them to 1.0 bar and kept it there you had a 0.5 bar difference.
they dont. that used to be a very typical situation on turboed cars. boost would typically drop from 0.8 bar to 0.5 bar at redline. thats why they were so easy to tune. if you took them to 1.0 bar and kept it there you had a 0.5 bar difference.
many old turbo cars use a solenoid that is computer activated to increase wastegate duty% after some rpm. Not necessarily because the exhaust gas pressure was high, but it certainly helps to make sure boost goes up and not down no matter what.
The exhaust 'valve' of the wastagate has a face diameter that directly influences the applied force from exhaust gas. Larger faces of larger valves allow more of the exhaust gas to apply a force to the valve and open it. A gate can open based on exhaust gas pressure alone. Think about this- if you left the spring out of the gate and didn't connect it to anything, would it still open? Of course common sense tells you that the exhaust is going to open the gate, because there is no force coming down from above. The same thing happens when there is a spring holding it shut- but now you see that the spring force might be overcome by exhaust gas pressure. There are all kinds of calculations online about how much force a given size face wastegate valve would take vs spring pressure rates and so forth, if you are interested it should not be difficult to find.
The exhaust 'valve' of the wastagate has a face diameter that directly influences the applied force from exhaust gas. Larger faces of larger valves allow more of the exhaust gas to apply a force to the valve and open it. A gate can open based on exhaust gas pressure alone. Think about this- if you left the spring out of the gate and didn't connect it to anything, would it still open? Of course common sense tells you that the exhaust is going to open the gate, because there is no force coming down from above. The same thing happens when there is a spring holding it shut- but now you see that the spring force might be overcome by exhaust gas pressure. There are all kinds of calculations online about how much force a given size face wastegate valve would take vs spring pressure rates and so forth, if you are interested it should not be difficult to find.
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On The Tree
Joined: Jan 2015
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Im just using a 1 piece conical filter attached directly onto the turbo. and as you can see last winter I got bored one day and half *** assembled my kit when my old lady wasn't home haha but it gives you a good idea of how my setup is
Thread Starter
On The Tree
Joined: Jan 2015
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talon I understand how a wastegate works, I just assumed it would hold pressure more evenly through the rpms than what mine seems to be doing. if I didn't know any better I'd say my gate is cracking at the right psi but it's being blown open further than it really should, causing boost to leak off more than anticipated. If you read my post I suspected this front the very beginning but you guys helped she'd some further light onto it. Im going to just go ahead and hook up my eboost2 and see what she does. thank you guys for the help, that's why I enjoy this site a ton of good info here depending on who you talk to
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
all I'm wanting to do right now is run this little 9lbs and be able to keep that 9lbs all the way to 6500. I was hoping I could accomplish this with just spring pressure but from what you guys are telling me I need a controller on this thing, likely due to back presdure. so now I wondering how all the factory setups keep their boost until redline without a controller
And as others say, more often than not OEM will allow higher boost in mid range, tapering off at higher rpm. But as with everything...there are many many variables.
Thread Starter
On The Tree
Joined: Jan 2015
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I'm good with the variables, that's to be expected with any build forced induction or not. this isn't my first build, but it is my first build trying to run off just spring pressure so this threw me off a bit. my last build i hooked up a manual controller before i ever started the car.I guess my only other question is should I reference my boost controller from the manifold or is it best to just reference it from the nipple on the turbo or does it matter and why? instructions on the wastage say use turbo for reference but peoplease are telling me different. I understand the loss of boost through the system but with a controller it seems it would make up for that loss no matter how I reference it. if I'm wrong please tell me, I don't claim to know everything in the world I just wanna know the proper way to go that way if I teach someone else down the road I actuslly know wtf I'm taking about lol
Last edited by boostedxs; Jun 24, 2017 at 11:37 AM.
9 Second Club
Joined: Nov 2003
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From: Norn Iron
I'm good with the variables, that's to be expected with any build forced induction or not. this isn't my first build, but it is my first build trying to run off just spring pressure so this threw me off a bit. my last build i hooked up a manual controller before i ever started the car.I guess my only other question is should I reference my boost controller from the manifold or is it best to just reference it from the nipple on the turbo or does it matter and why? instructions on the wastage say use turbo for reference but peoplease are telling me different
But as you're experiencing a drop at higher loads, you could reference close to the throttle but on the boost pipe side.
But ultimately if you have a lot of EGBP or some other build limitation, then it will need a different fix which could be a different plumbing configuration for the gate, or a programmable controller.
I suspect that if you are using wastegate, andboost frops off, then it will do the same with the controller. Most controllers use a solenoid with a commanded duty cycle. Since the commandedduty cycle is fixed, whatever is causing your drop off with just wastegate will be seen with the increased boost as well. Now, if the controller had the ability to increase duty cycle during the pull (scramble mode), then you could mask the boost falling off by increasing duty cycle.
9 Second Club
Joined: Nov 2003
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From: Norn Iron
I suspect that if you are using wastegate, andboost frops off, then it will do the same with the controller. Most controllers use a solenoid with a commanded duty cycle. Since the commandedduty cycle is fixed, whatever is causing your drop off with just wastegate will be seen with the increased boost as well. Now, if the controller had the ability to increase duty cycle during the pull (scramble mode), then you could mask the boost falling off by increasing duty cycle.
Thread Starter
On The Tree
Joined: Jan 2015
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I have verified that fire ring is installed and looks to be seating properly. what I need to do it build a rig to test my wastegate that would probably solve this issue pretty quickly. bov is on exit side of intercooler, this is how all the huron speed t4 kits are set up and I've never heard of this issue. I will check on all my lines though and make sure nothings leaking. I'll keep you guys updated on the fix. I don't have my car at home it's at my shop but I'll jump back on it this week at down point. thak you guys for the input