Cant build boost over 15psi in 2nd

[techghost]

I'm also almost similar issue as well after upgrading to a 3076r. the boost starts to build up at 4k or so but even with the External WG disconnected i dont reach anything higher then 15/16psi in 2nd gear in third i reach 18psi or so

i'm stumped on my issue as well, i've removed BOV, there isnt any boost leak anywhere, Manifold is ok as well; no exhust leaks, WG diphagram is ok too, i've also removed the airfilter. i dont know what is causing the delay and limited boost

TUrbo spins freely at idle (its a dbb garrett GT3076r turbo), car idles very nicely and sounds healthy.

what could be causing this issue??

 

[skatershawn]

have you checked for exhaust leaks?
and do a boost leak test?

 

[techghost]

@skater
Yes, no exhust leaks or boost leaks till 25/26psi.

Another thing to add here is that my turbine housing says 1.06ar (T3) and compressor is 0.70ar.

 

[RadDsm]

That is a really large turbine housing, I wonder if that could be your problem.

I'm guessing the reason you are reaching higher boost in 3rd is because 3rd gear will put more load on the motor than 2nd does.

 

[techghost]

Yes! i understand that i will push more boost in 3rd and much more in 4th compared to 2nd as engine has much more load on it
but i initially thought i will push 20psi or so easily on 2nd and 24/25psi in 3rd..... but if i go on with 18psi boost i'm not even close to the turbo efficiency.... i'm just flowing around 26/28lbs which is much lower then my last Big 16g (where i pushed 37lbs)

 

[aero_sallee]

Yes! i understand that i will push more boost in 3rd and much more in 4th compared to 2nd as engine has much more load on it
but i initially thought i will push 20psi or so easily on 2nd and 24/25psi in 3rd..... but if i go on with 18psi boost i'm not even close to the turbo efficiency.... i'm just flowing around 26/28lbs which is much lower then my last Big 16g (where i pushed 37lbs)

With that large turbine housing I'm not surprised at the late boost. What spring is in the wastegate? A too low pressure spring will blow open even with the boost source disconnected.

Is the fire ring/valve seat installed properly?

To test for the spring being forced open you can connect the boost source to the top port and take it for a quick pull. The boost will force it closed even with a weak spring. Just make sure to watch the gauge carefully an be ready to let off. Assuming that is your issue boost will go wild. Its a good test for that problem though.

 

[techghost]

@aero
Thats right, i was thinking about doing the same. Connecting the top port of WG will push boost and force the diaphagrm down and will make sure its closed to maximize boost. Currently neither top nor side port is connected although i have a custom spring (which opens up at 20psi or so, its tried and tested on another EVO8)

I assume that wastegate is not opening up as i dont hear WG shouting but i would still do this test to eliminate issue.

Infact i will test out another wastegate in few days (as soon as i get my hand on it) and mean time i'm planning to open up my intake plenum to check its gaskit as well.

Fire ring is seated perfectly, i doubt there will be a leak there.