Jetn3

You can try a different vac/boost source. I use my old brake booster line for vac/boost source for my wg,bov, and gauges since I did a hydro boost conversion.

timmay208

iTrader: (4)

im kind of fighting same thing. 11.6WG spring in my tial but its only making 9-10lbs of boost. however im pulling the source of my boost off the turbo housing before the IC so that is prob why im losing a little. Im going to try pulling the boost reference off my vac block that is showing actual manifold pressure

GRRR65GTO

Yeah Ive read about that before, the intercooler and pipes kill some boost before it gets to the manifold.

One would think the boost on either side of the throttle blade would be the same because my reference line is before the throttle blade

timmay208

iTrader: (4)

So does it hit 10 and fall to 7 or only hitting 7 no matter what?

GRRR65GTO

Its hits 7 no problem and as it revs up to shift it starts falling down to 4 or 5. I know an electronic controller can compensate for that buts its not a race truck

timmay208

iTrader: (4)

you have another problem if its not holding spring pressure. a BC would just be a bandaid.

if its a 7lb spring it should have no issues holding 7 from start to finish. Do you have a Vacuum block or anything. I would double and triple check the line to the WG and maybe run a new line from either the intake manifold or a vac block

Atomic

iTrader: (42)

Sounds typical really. Backpressure increases as RPM rises, forces wastegate open more. The spring rating is really only for one point, and is usually rated for smaller engines.

timmay208

iTrader: (4)

Yea without having a gauge to watch back pressure its hard to say, but it it should have no problem holding WG pressure to redline

Atomic

iTrader: (42)

Why do you think it shouldnt have a problem?

GMCtrk

iTrader: (27)

I think this is predominantly an issue with the small turbine on that turbo. I'm seeing a similar issue with my baby 74mm turbine, which isn't helped by the fact that I've got about a mile of 4" piping behind it. I'm sure a cutout would help tremendously. This issue seems to be boost controller independent in my case as eventhough I increase the overall boost, the boost curve stays the same.