Varying boost on turbo'd 4L
After recently rebuilding my motor, i have been driving my car around for a couple of weeks without a boost gauge on, i had noticed that i had losed a little bit of power in first gear, but second and third felt the same.
Today i stuck the boost gauge on a went for a drive, i have 9psi in first gear, and 13psi in second, now previously i was running 13psi all gears and not changing.
Anybody got any idea why?
My thought was that i did have the turbo off and had changed the angle of the outlet slightly and also therefore varying the wastegate position, i have a rather bad designed dump pipe, whereby the wastegate doesn't flow properly into the pipe, and i think that when i have altered the position i have lowered the wastegate pressure, and the dump pipe is causing this inconsistent boost pressure, could this be it?
The turbo is a IHI RHB6 VJ23 with internal wastegate, it is factory high flowed and flows 450hp.
I pulled the car right out in the revs to 6500RPM, and it doesn't back off from 13psi, and the minute i nail it in second it has 13psi.