hello all,
i am having some problems with my boost deacreasing with rpm's. at about 5000 the system hits 18 psi then by 8000rpm drops to about 14-15 psi. the car uses AEM EMS. i have a manual boost controller (turboXS) and 44mm WG with a 13psi spring. i have checked both the manifolds for leakages but have found none. i am thinking it may be piping or something to that effect. after a bit of tuning and such the boost wont drop as much so now we are sitting at 18psi dropping to 15psi. any insight to the problem, etc. would be great. thanks

brett

 

we need more info, whats your setup, what turbo are you running? etc

 

Sounds like the problem I am having. I'd say turbo size. same thing happens to me with the t25. the turbo is to small to hold more than 15psi for long periods of time. You may be ready for a larger turbo. g/l

 

sounds liek boost spike. Id ditch that manual boost controller in favor of an electronic one. i coudl never get manual boost controllers to work properely, mine woudl spike as high as 14 psi then settle at 9 (this was with an ihi rhb5 though, with the 14b the boost is much more solid.

 

Yah im having the same problems, I can't raise up my boost on my 14b because I have lots of problems with MBC's boost spiking.

 

thanks for the replys. it was the boost controller. i got a ball bearing one from my brother and it holds fine...just needs tuning now. thanks again oh and go with a hallman and such if using MBC. peace

brett

 

Joe P mbc's

 

ok now here we go again. the boost is still doing it and it only happens when on the dyno. i have several logs when out on the street and the boost holds fine, but when on the dyno it falls off 2-3 psi (as described above). i am getting frustrted and think i may have something to do with air flow and passing air, any help again would be appreciated.

the setup:
ls/vtec, precision sc61, 8.5 c/r, trr exh. mani (equal length), jg intake mani, streetimports 650hp intercooler, 2.5" charge pipes, 2.75" downpipe, thermal 3" exh. anything else? AEM EMS, msd wires, box and coil...

thanks
brett

 

my dad's talon does that same **** with the turbo XS MBC, it is just the nature of it, atleast it seems that way.. It will go to 22 then fall to 20, then 18... what a pain.

 

going to try and do a EBC from apexi, just to see if it works...thanks

 

anyone, all comments are appreciated

brett

 

I have the same damn problem. TurboXS mbc, wrx turbo, 38mm tial wastegate with 8psi spring. When i try raising boost it will hit 10psi and then settle back around 8psi . F*ck this mbc crap. I'm just going to get a damn 10psi spring

 

way to be, that is what I did.. just played with the waste gate untill I got what I wanted out of the stock one.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93turbo16 &raquo;</TD></TR><TR><TD CLASS="quote">way to be, that is what I did.. just played with the waste gate untill I got what I wanted out of the stock one.</TD></TR></TABLE>
i wish the springs weren't so expensive though

 

springs are only 25 bucks (add 25 more for 1.1bar+), and be sure to specify which wategate it is you are runnig when ordering.

 

$25 from where?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOHC_MShue &raquo;</TD></TR><TR><TD CLASS="quote">$25 from where? </TD></TR></TABLE>

i think viren b18bturbo has them for that much

mbc=trash

 

cool

 

we've tried the GM solenoid and have had to much difficulty in setting it up/getting it to work properly...i am not wasting money on the controllers, they are donor's.

the mbc source is from the turbo then connected to the side of the WG.

 

Everyone runs MBC's with success, probably has something to do with not ramming as much air into your intake on the dyno as you would while driving....

I have a 14.7psi spring and am only gonna use the mbc to bump it to 16-18

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by brettII &raquo;</TD></TR><TR><TD CLASS="quote">we've tried the GM solenoid and have had to much difficulty in setting it up/getting it to work properly...i am not wasting money on the controllers, they are donor's.

the mbc source is from the turbo then connected to the side of the WG.</TD></TR></TABLE>
try connecting it to the intake mani and not to the compressor nipple. That way it will be opening at the actual boost your motor is seeing...otherwise its not taking into acount the pressure drop across the intercooler. It should hold your boost a little more steady if its attached to the intake manifold.