my setup:
B18a with greddy SOHC kit (td04h-15g)
FMIC, 450cc injectors, ghettodyne powered
2.5in high-flow cat, 2.5in cat-back w/ dynomax super turbo muffler

my problem is when boosting, my boost drops to 3-4lbs when I get past 5000rpm, whatever boost I set with my MBC

example: I'm in third @ 2000rpm, I floor it and I get 6-7psi by 2600-2700rpm (depending on my mbc) then, as I accelerate, my boost slowly decrease down to 3-4psi @ 5000rpm and up ...

this is really annoying, I feel more power at 4000rpm @ 7psi than 6000rpm @ 3psi

my turbo seems to be in good shape, as there isn't any oil leak, shaft play and it spool fast

how can I see if it's a leak in my charge pipe?

also, I had to make a 90degrees bend in my charge pipe just after the turbo
could it create restriction? It isn't mendrel bent or anything, it's really a straight pipe that I saw at 45 degrees and welded it so basically it looks like this: L

thank you for your help!

 

also, could it be because my b18a is burning 1qrt of oil every 500km when I floor it alot? (maybe loosing pressure in a bad ring land ..)

 

ya, try a compression test. but my guess is the turbo it too small if its meant for a 1.6l sohc civic motor.

 

no it's not the turbo. if you have a boost leak then you should be able to hear the leak somewhat if you listen hard...i know when i had a boost leak on my GSX i could hear the air rushing out. i would doubt the rings being the problem. just check all your connections and get them all tight and snug. on a boost leak like that whats probably happening is you hit that 6-7 psi and it's just enough to open up a small enough hole somewhere in your connection to let pressure bleed out until you hit vacuum again...

 

in fact I can hear a whistle when I boost that is about the same sound as when the BOV opens but I tought it was the turbo spooling (I can't figure where it comes from)

it's like a Shhhhhhhhhhhhhhhhhh(accelerating) PSHHH(BOV opens) (kinda hard to explain)

and I'm not hitting vaccum or 0boost, just dropping slowly to 3-4 lbs

I looked at turbo charts and the 15g is bigger than a T-25, about the size of a 14b, so I don't think (well I wish) this is my problem

if it can push 14psi through a D16z6, it should be able to at least push 8-9psi in a B18a

 

check all the hose clamps and couplers then.