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I love sequentials!
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Discussion Starter · #1 ·
I know I'm not the first to do this, but I haven't ever read about it on the forums ...

Since I went BPU a few weeks ago, my car would spike to 18 pounds and then fall to 15, it also would have a lull in transition. After I put my SP manifold on, it became more pronounced, so I started eyeing up the wastegate.

Instead of allowing boost to just dump into the atmosphere, I decided to add vacuum to the wastegate to actually help KEEP it closed. I thought I was going to have to run a vacuum line from somewhere near the compressor housing entrance, but it ended up just being able to bypass the solenoid that bolts to the front compressor housing to have the same effect. The car now holds 17 pounds all the way to 8,000 rpms and runs like a raped date :D .

Has anyone else done this, something like it, or any BPU tricks to try and make things a bit more efficient? It would be nice to have a compilation post with all of the small tricks people have discovered over the years.

I think I'm going to shim the wastegate next.
 

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I Solve Problems
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Sounds like the equivalent as the "spring mod" basically.
 

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"SP manifold" and "Dump boost into the atmosphere"?

I don't understand, BPU doesn't include an aftermarket exhaust manifold and external wastegate.
 

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I love sequentials!
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Discussion Starter · #4 ·
You could have PMed me, but in case someone else is confused. It's an intake manifold, I'm still using the stock twins in sequential.

Most people, when the pull the hose to the number one turbo, are just dumping boost into the atmosphere


crossways said:
"SP manifold" and "Dump boost into the atmosphere"?

I don't understand, BPU doesn't include an aftermarket exhaust manifold and external wastegate.
 

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Sorry for the confusion turbosupra.

Neat idea. But is there a way to do this and incorporate a method of boost control also.
 

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It may be just as effective as the spring mod depending on how sensitive the diaphragm is to vacuum. And I suspect this method would help keep the wastegate firmly shut as long as possible for great spoolup. The only difference is that you can still retain some level of adjustability with the sping mod (assuming you have a boost controller attached). Either way, I would advise paying close attention to boost and A/F readings up top when doing this.

mifesto drop me a line. I'll hook you up.
 

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maybe im wrong but that sounds like the bleader T mod. or, its called somthing like that
 

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Discussion Starter · #11 ·
You could still run an electronic or manual boost controller and have it tapped into the short 4" rubber line that runs from the compressor housing of turbo #1 to one of the wastegate nipples ... at least this is what I am going to try, I can post results if anyone wants.
 

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Brad,

Are you planning to dyno anytime soon. Are 264 cams in the future for you? I'd just like to compare graphs to when i was BPU with cams/VPC/GCC and front mount.
 

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ahhh the good ol' days of stock twins...put a heavy ass spring as ur wastegate spring mod, n ull be fine, but ur idea is still a good one. i ran 22pnds on mine on a cold night n it would hold 21psi no problem...
 

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Discussion Starter · #14 ·
Hey Alex,

I actually am going to dyno pretty soon, and yes I do want to use 264's. Where abouts in MD are you?


Alex D said:
Brad,

Are you planning to dyno anytime soon. Are 264 cams in the future for you? I'd just like to compare graphs to when i was BPU with cams/VPC/GCC and front mount.
 

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Discussion Starter · #16 ·
Alright, well I may be using a dyno as far away as MSP's, but you are welcome to go if you like. I have yet to get my cams and I'll probably be using a fields controller instead of an afc, but that shouldn't present any difference.

Do you ever head over to Northern Parkway?



Alex D said:
Northern Baltimore County.
 

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turbosupra said:
Alright, well I may be using a dyno as far away as MSP's, but you are welcome to go if you like. I have yet to get my cams and I'll probably be using a fields controller instead of an afc, but that shouldn't present any difference.

Do you ever head over to Northern Parkway?

Every once in a while. I haven't been there in about a year now. I'll be looking forward to hearing the results back from your dyno. I'm not too familar with the Fields controller but i'm sure you'll have similar results as the AFC.
 

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sngledsupe said:
ahhh the good ol' days of stock twins...put a heavy ass spring as ur wastegate spring mod, n ull be fine, but ur idea is still a good one. i ran 22pnds on mine on a cold night n it would hold 21psi no problem...
I've heard allot about the spring mod. Does anyone know if it will make you boost over the boost controller setting? someone thought it might so they didn't recomend it.
 

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turbosupra said:
You could still run an electronic or manual boost controller and have it tapped into the short 4" rubber line that runs from the compressor housing of turbo #1 to one of the wastegate nipples ... at least this is what I am going to try, I can post results if anyone wants.

I'm not sure how this is going to work, because you will be introducing pressure on one of the wastegate nipples and vacuum on the other nipple which should reduce the resulting pressure. So this will in fact raise boost higher than normal because the effective pressure the wastegate sees will be lower than with a boost controller alone. But you won't have an effective vacuum to keep the wastegate closed at higher RPMs like you would by a pulled wastegate hose +vacuum connection (like in your initial post). Correct me if my thinking is wrong.
 

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Discussion Starter · #20 ·
I'm not 100% understanding what you posted, but let me reitterate what I said and see if I can make more sense of it.

Right now I have a baseline boost curve, it's a result of the boost/vacuum combo I have, but none the less it's there. Then I have a device inline that will modify that curve and will use a reference to compare what I set it at, to what is the intake manifold is actually seeing.

Regardless whether the solenoid in the boost controller unit stays completely closed until the last second (fuzzy logic) or if it works more along the lines of a bleeder valve, the other source will still see vacuum ... so in actuality it may even work better, if the solenoid stays closed (say until about 15 or 16 psi) and then opens. During that build up, the vacuum is going to keep the wastegate closed by pulling the diaphram closed and then when the solenoid allows boost into the equation, it will help balance that out.

This is theoretical, I'll let you know real world results when I get the chance.
 
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