I was putting metal locking nuts on my turbo studs (they work great btw! a lot better than lock washers or star washers) and took the external wastegate off (it was doing this before I took the wastegate off, just explaining why the vacuum line was off), when I put it all together I forgot to attach the vacuum line. I suspected I might have forgotten, but I took it for a ride and it was opening at 12-13psi like it was supposed to, so I didn't worry about it (might been getting to 15psi at one point which is fine with me). I eventually double checked the line and it was off, so I attached it, and boost stayed about where it was.
My question is, why is the wastegate opening at 12-13psi without a vacuum line? It should be a 10psi spring. I have it dumped to atmosphere, so I know when it's opening. I can hear the turbo spooling fine at lower RPMs and the BOV will open if I accelerate kind of hard without getting in to boost, so it seems like the wastegate is shutting all the way.
One other thing, the turbo seems to spool late (and has been this way before, with both internal and external gates). It doesn't seem to start actually building pressure in the engine until about 3000RPM. It's a TB0348 (Grand National), which should be similar to a S60 on the compressor side, and it has a .48 turbine housing on it (the exhaust wheel looks like a fan compared to the scoops of the TD turbo, supposed to be a better design).
I have a 3" exhaust
+40s
Boost Button cal
12* base timing
Ported head (shaved .011 I think, and I have an offset cam key)
52mm TB with 2pc intake TB inlet ported to match (ish, I could go slightly larger honestly, there is still a slight lip, maybe when/if I go to a Holset)
5-speed
Walbro 255
3-bar map
FMIC
Ported exhaust manifold (not hugely ported, but ported larger than gasket for reversion, and the #2 runner bump ground out. I was using sanding rolls, so probably not as open as a vendor might have)
TBI Cam
PT Lifters
MBC (ball and spring, not bleeder)
So two issues that I want to address I guess:
1. Wastegate opens at 13psi with no vacuum line (I don't hear the wastegate open until then)
2. Turbo also seems to build boost late (although I can hear it spinning up before it builds boost). It has done this before the external gate too.