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.

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.

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.

Not hitting 10psi until 3800rpm sounds laggy for a 2554r. Sounds like there is not a proper preload on the wastegate.

Definetly seems to be the next obvious solution. The one i completely failed to check.......gun barrell in mouth....pull trigger.

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.

Try disconnecting the wastegate, and securing the flapper closed. Be careful, obviously, for a boost overshoot.

I like that idea.

A lot.

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.

:rofl:

5.5 years on mt and I finally help someone.

:blushing:

Your checks in the mail. Skidude's also.

Yay, I have 2 props!