It's a 88TII and I have the RB turbo back, TID, HKS filter, FD fuel pump, FCON, GCC, EGT, and boost gauge. I recently installed a rebuild S5 turbo system with ported wastgate. Without a MBC the boost will creep to 10-11psi on third gear all the way up to 5500rpm (why is the creep still bad with a wastgate ported S5 turbo??) It will drop to about 8psi from 550rpm to 6600rpm (<--- is it normal??). If I don't install a MBC then it can't hold the boost at 10-11psi all the way to redline. If I do install a MBC then can it control the creep or I have to set the boost more then 11psi?? I only want 10-11psi all the way to redline. plz give me some suggestions.
Don't know why the previous post doesn't work.
Thanx

 

I am not sure as to why your boost drops to 8 psi but I can make a guess.

the turbo can only flow a certain # of cfm's. Boost is pressure, not cfm's. 500 cfm's at 4k and 500 cfm's at 7k will get you different pressures, because the engine is consuming different amounts of air. If you hit max flow before you run out of redline, then your boost drops. Does this sound logical?

boost controller will not control creep, only more porting will.

 

NO boost controller, whether a $5 DIY manual one or a $300 electronic one, can lower boost or control boost creep. Boost controllers can only RAISE boost. That's it.
The only way to solve boost creep is to improve flow through the wastegate port(s). Porting them is the first step, better downpipe design is the next.

 

how is a better downpipe design going to help boost creep unless you have it like the one in that thread you posted?

 

The stock downpipe design sucks. The back plate is blocking a lot of air even coming out of the wastegate. Fixing that would probably solve creep better than porting it lol.

 

I ported the wastgate already and I replaced the factory dp with the racing beat one (unless the racing beat dp is also a bad design). Don't you guys think that my boost creep problem is serious?? It is a ported S5 turbo wastgate. Any S5 turbo users have the same boost creep problems??

 

If you look at the wastegate, the air coming thru it must make a left 90deg corner to get into the downpipe, then a right 90deg corner to get into the downpipe. That would reduce airflow significantly IMO. Not one downpipe Ive seen fixes that.

 

That's exactly what I was refering to. Then you haven't been looking hard enough!

Click here

 

Hell, I'm having a problem keeping the boost down on my ported motor, I ported my wastegate, and matched the exhuast runners, right now I'm boosting to 7-8psi with my wastegate OPEN!!!!