I have a 5.3 and I'm trying to run 15 pounds at the track. With my 15 pound spring in boost gradually starts dying off when I start getting into the higher rpms. Low rpm like when it first shifts it'll make 15 but then by the time it shifts is only making about 12 to 13. I have a trick stage three kit with the 76/68 turbo. I have looked and can't find a leak anywhere so my question is do you guys think it's a boost leak or do you think I simply have too small of a turbo to try and keep up with this amount of boost. Thanks in advance

 

Inter cooler restriction or to small for the power?

 

I would guess intercooler. Loss of boost after cooler.

 

I would spray some water around the welds just to make sure. Sounds like boost leak to me.

 

Are you reading your boost gauge and referencing your wastegate from the same spot?

 

No my wastegate is referenced right off my turbo and my boost gauge gets is signal from a line right off the intake...maybe I should reference my boost gauge and my waste gate off my intake?

 

Sounds about normal for a turbine that size.



Those horizontal lines (speed lines), you are basically riding it left to right. Notice how they go down.

 

you want your waste gate referenced from the turbo housing,

are you running a boost controller?

 

Try a boost controller.
Or
use more spring to start.
The fall off isn't boost leak.
It's the turbo is not able to feed that PSI at that engine speed at that spring setting.
Not that the turbo can't push more air.
But it will become smaller and smaller returns.

Next step up in turbo is a 74/75. Or 76/75CEA.

I like running the gate at the intake.

 

I have an ams 500. At the track just to see what happens tried to set the boost on 18 pounds. Same thing it would hit 18 then fall to 14 or 15 before it shifted. I'm with rick I think I'm simply running out of turbo