Rb25 Slow To Build Boost

[TerribleOne]

I've got a mildly modded RB25 with a Gizzmo IBC and I noticed that for me to get full boost I really need to rev the guts out of it to see 11psi. Ive fiddled with the gain settings on the controller which makes it a little better but if I push the gain too much the boost isn't very steady.

Is it normal to have to push 5k+ rpm on a RB25 with standard turbo to see full boost? My friend has a RB25 with only cat back exhaust and Profec-B and his seems to reach full boost (11psi) at maybe 3k rpm and feels much more responsive than mine.

Has anyone else had problems like this with a Gizmo IBC?

My RB25 has:

Jazma 3.5" exhaust and unknown stainless dump

Yellow Jacket coils

FMIC

Standard airbox (I hate pods)

Upgraded Walbro pump

Custom alloy intake manifold with internal bellmouths and front facing TB

What looks like GTR BOV plumbed back

I might bypass the IBC and use a bleed valve to see if it builds boost any better if nobody has any other ideas.

Thanks!

I bought the car super duper cheap with all this stuff done to it so everything is a bit unknown. I only use it to drive to work and back.

Edited January 25, 2010 by TerribleOne

[Ultimategtr]

Sounds like 1 has the wastegate fully open, check your solenoid and see whether its hooked up correctly.. refer to the gizzmo's install diagrams..

If that fails, disconnect it and revert back to the solenoid to see whether its your ebc doing it (or lack of).

If you T the wastegate actuator directly off the J-pipe(pressure source) then you should see at least 5-7psi at like 2-3k.

[JonnoHR31]

if your using an ebc then bypass the stock solenoid, you dont need it.

[TerribleOne]

From what I can see the standard boost solenoid is not connected, I think its mounted in the passenger side strut tower still and the Gizzmo one is next to it.

Is it worth disconnecting it and using a bleed valve to see if it improves?

Judging by the horrible shit I had to fix in the engine bay when I bought it anything is possible.

The guy who I bought it off sold it cheap becuase it ran like an absolute dog. Wouldnt idle, wouldnt boost, had a horrible missfire, would stall, pump out black smoke on idle. I replaced the AFM which improved it 90%, fixed a few large vacuum leaks around the intake manifold and TB, replaced the 02 sensor and it runs a treat. Just need to get my head around this boost issue and it should really show the full potential of the car.

[soturi]

I have seen this exact sympton after a damaged intercooler.....my mate got his car towed and it got slightly damaged getting pulled up onto the truck...and after that it was really slow to reach 10psi