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Old 04-25-2012, 11:35 PM   #1
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Default can't make more than 10lbs boost

Title's pretty straight forward. i have a few ideas what the problem might be but I'd like some educated input as where to start first. the 1.6 is pretty wore out and compression is suffering. Using a gt2554r, turbosmart bov and manual controller. 550 injectors and a megasquirt. Homemade log manifold with full 3" exhaust no cat. 2.5" piping with intercooler.
Ran it on the dyno a few days ago and made 203hp. What i know is that my bov is not leaking and that when i hit 10psi at around 3800rpms it holds it nicely throughout the rest of the rpm range. BUT, no matter how much boost i try to dial in i can't make anymore.
My initial thought is that i might have too much backpressure on the turbo. Despite having 3" exhaust my downpipe does not make a curved 90 degree bend but rather a straight right angle 90 degree bend like an "L".
Maybe i've given enough info to stir up some theories. Thanks.
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Old 04-25-2012, 11:56 PM   #2
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Sounds dumb, but all the couplers good and tight?
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Old 04-26-2012, 12:18 AM   #3
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Sounds dumb, but all the couplers good and tight?
Yes. Everything after the turbo has been checked and monitored thoroughly. And just to throw it out there, when i crank the boost controller way up i get a spike up to 12-13lbs but quickly drops back down to 10. Datalogging confirms my autometer gauge btw.
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Old 04-26-2012, 08:03 AM   #4
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Does the wastegate stay closed? It's possible the spring is tired/weak so the pressure is forcing the wastegate to open a little even though it is not getting the signal to open.
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Old 04-26-2012, 09:37 AM   #5
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Not hitting 10psi until 3800rpm sounds laggy for a 2554r. Sounds like there is not a proper preload on the wastegate.
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Old 04-26-2012, 05:55 PM   #6
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Does the wastegate stay closed? It's possible the spring is tired/weak so the pressure is forcing the wastegate to open a little even though it is not getting the signal to open.
Definetly seems to be the next obvious solution. The one i completely failed to check.......gun barrell in mouth....pull trigger.
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Old 04-26-2012, 06:55 PM   #7
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Not hitting 10psi until 3800rpm sounds laggy for a 2554r. Sounds like there is not a proper preload on the wastegate.
It might be kinda laggy, but i have no basis for comparison on this old wore out motor. Aside from it''s dying compression i could think of a handful of reasons why it might be slow to spool. But i don't think any of those reasons are related to my current problem.
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Old 04-26-2012, 07:13 PM   #8
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Try disconnecting the wastegate, and securing the flapper closed. Be careful, obviously, for a boost overshoot.
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Old 04-26-2012, 07:35 PM   #9
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Try disconnecting the wastegate, and securing the flapper closed. Be careful, obviously, for a boost overshoot.
I like that idea.
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Old 04-26-2012, 07:36 PM   #10
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A lot.
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Old 04-26-2012, 08:11 PM   #11
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Well we can go ahead and bring this thread to a close. Close hangar wrapped around wastegate, simply put, freakin' rocked my world. Last time i had a hardon like this was when i was watching justin bieber play the flute.
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Old 04-26-2012, 08:24 PM   #12
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Old 04-26-2012, 08:28 PM   #13
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5.5 years on mt and I finally help someone.

:blushing:
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Old 04-26-2012, 09:20 PM   #14
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5.5 years on mt and I finally help someone.

:blushing:
Your checks in the mail. Skidude's also.
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Old 04-30-2012, 08:10 AM   #15
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Yay, I have 2 props!
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