Heres the setup first:
96 ex civic D16y8
Srp pistons 9:1, Eagle rods, Port and Polished Head(<<Stock)
t3/t4 .50/.48
Revhard DRAG manifold
2.5 DP and 2.5 custom exhaust
Tial 38mm wastegate
Rfl BOV
TurboSmart single stage MBC
550cc injectors
Hondata
I had this setup tuned at 245whp and 202wftq at 15 psi. We were havin some troubles with boost, I actually wanted about 19 psi but the wastegate gasket was blown. So I fixed that and still only 15 psi. My question is why? I think that it could be several things, but not sure. The MBC might not be able to raise boost that high? I have a 10 psi spring(It only reads about 8-9 with the controller switched off) in the wastegate. A friend said that some controllers only raise it about 5-6psi over base wastegate. Should I get the 13psi spring? Or could it be the head? The dyno sheet showed my HP fallin off about 6500-7500 rpms. The tuner said the car was running out of air in the top end. Does any of this sound right or is there something im missing.
oh yeah, no boost leaks anywhere. I have fixed them ALL.

 

You're losing power because you're running the stock cam and valvetrain. I wouldn't rev the stock single cam valvetrain past 7100 or so, and the cam definitely won't be making power up there.

 

Why not just get a larger trim T3/T4 and run less boost?

The restrictions I see in your setup that could pose a problem are the downpipe, exhaust, turbo, and/or manifold.

 

try doing a couple runs open down pipe, with a .48 your not gonna have an agressive top end, even on a d16 so you should only expect a strong midrange. I dont think your head is the issue, my friend is making 450hp on a stock head, youve got problems else where. The fact that your not getting 10 psi on your 10psi spring leads me to believe youve got a leak somewhere. might be in the manifold, or its the lines or charge pipes and you just havent found it

 

I will check again for leaks, but I dont think there is any. I rebuilt the turbo a fews weeks ago from .63 down to .48, because the lag was really bad and 12 psi was all I could make. Now I can make 15ish about 4500-5000, but I built this engine for 300, and 245 is a little short of that. Is there a way I can bypass the wastegate to see for a second if it can boost higher than 15-16??

 

yea disconect the vacuume sorce to the wastegate and be carefull. I can tell you that ill be making 300hp or around that at 20psi with my 50 trim 63 turbine, so 240hp at 12psi actually sounds about right. That .48 is gonna have a hard time getting to 300, so good luck

 

Well I found 2 leaks . One at the charge pipe after the intercooler,and one at the boost controller tee. I tested to 15psi with my boost leak tester and I didnt hear any leaks. The leaks were VERY audible at only 7 psi and pressure dropped fast. Now it holds 15 psi for a while. I will test drive it tomorrow and if it still doesnt boost past 15-16, then I will try to bypass the wastegate.

 

Get some better clamps and couplings.

 

what are you using to test? your gonna notice that some leaks only show up at different amounts of pressure, so make sure your tester can go as high as 20psi or so. Your gonna wanna get some really soapy water and a spay bottle and start spraying all the couplers and vacuum lines.. You might not hear it, but this will help you see a leak. The soapy water will bubble up once you start adding pressure to system. Do a search because Jafro did an awsome write up on making a boost leak cheker and then how to check the system out.