Boost spike after MBC install

[kris_pran]

Its been a while since ive been here :-X

Just recently bought a V5 STI w/ a rebuilt Fully Forged V7 Short block and V4 Heads/VF24 Turb.

Apart from the engine the car has an aftermarket 3 inch exhaust from the mid section but still running the restrictive factory downpipe, HKS Bov and a shitty pod flilter with a decent heat shield beside it.. Apart from that everything else is stock.

Before the installing the mbc, factory was holding boost up till 18psi constantly. This is my 2nd sti and i have fitted a mbc a few times. After the install took it for a spin

1st - 18psi

2nd - 18psi

3rd - 15psi after 4000rpm spikes to 20psi

Stopped testing after that lol.

Checked for leaks and loose hoses. Nudda nothing everything was tied up.

[subieboy]

What are your settings for the EBC?

Is the solenoid's vacuum hoses hooked up the right way round?

Is the solenoid correctly hooked up to the EBC?

Cant think of any other reasons atm...

[Kiwi_Fozze]

he's using a manual boost controller.

theres the issue, right there.

[subieboy]

 kwi_fozze said:

he's using a manual boost controller.

theres the issue, right there.

Yeah saw that hence my not so good an tender hint of EBC...

Spend all that money forging a motor then skimp on the controller...

[kris_pran]

MBC is the problem?

They work perfectly fine, i have never seen any defects to them. Had them hooked upto my previous 360hp evo 8 held boost at 24psi all day long. Before that i had one on my version 4 sti that held 18psi.

For some odd reason this one decides to spike on 3rd and after, 1st and 2nd are holding up fine.

Ill upload a picture of how its hooked up soon.

[Kiwi_Fozze]

a properly set ebc shouldnt spike. ever. a manual boost controller is basically a spring attached to a boost leak. an ebc is a hell of a lot more accurate. more reliable, etc etc etc.

but hey, if you like mbc's, by all means, knock yourself out.

[G-unit]

 kris_pran said:

Its been a while since ive been here :-X

Just recently bought a V5 STI w/ a rebuilt Fully Forged V7 Short block and V4 Heads/VF24 Turb.

Apart from the engine the car has an aftermarket 3 inch exhaust from the mid section but still running the restrictive factory downpipe, HKS Bov and a s***ty pod flilter with a decent heat shield beside it.. Apart from that everything else is stock.

Before the installing the mbc, factory was holding boost up till 18psi constantly. This is my 2nd sti and i have fitted a mbc a few times. After the install took it for a spin

1st - 18psi

2nd - 18psi

3rd - 15psi after 4000rpm spikes to 20psi

Stopped testing after that lol.

Checked for leaks and loose hoses. Nudda nothing everything was tied up.

so why did u install 1 when its already holding 18psi?

[kris_pran]

Reason why i installed one is because im planning on getting it tuned next month.

If MBC really is the problem then i might as well invest in a EBC :-\

[G-unit]

please tell me thats not a $25 trade me job?

[kris_pran]

Thats before i took it for a drive. Its just temporary sitting there in the photo..

[G-unit]

id just go with the stock set-up or a EBC

[ADIKT]

Ditch the cheap crap. Fork out for a decent controller.... You can get a mint EBC under 250-ish. And you wont have any spiking

[Kiwi_Fozze]

i had that exact same boost controller. in cabin, i reboved the breather hose so it was venting in cabin. suspect? yes. unstabe? yes. it actually came on full boost slower than the ecu control. personally, i'd leave control to the ecu or with an ebc....

[Pappu1]

that is a sh!t boost controller

get a decent mbc

i bet u had a better one in the 24psi evo??

i have had a older turbosmart boost tap and it didnt have issues like that

yes there was a slight overboost but maybe like a pound or so

compared to a electronic controller it wasnt too bad and near the same results (boost curve measured on torqu performance dyno)

anyway...get a better controller man

that one is sh!t...

[resurrection.inc]

you my aswell be open boosting it with one of those.

[Guest]

hey man were about is that top hose going to?looks like everything else is right

also sometime the taps are the wrong way round.so mayb do abit of swaping n stuff.

btw internals wastegates are crap for holding boost.

go external or buy a decent ebc

[xsvpwr]

 sti8u said:

hey man were about is that top hose going to?looks like everything else is right

also sometime the taps are the wrong way round.so mayb do abit of swaping n stuff.

btw internals wastegates are crap for holding boost.

go external or buy a decent ebc

Internal gates are fine, stop trying to cause an argument

[vorigan]

sounds pretty normal for a MBC

[WRXONP]

lol who would buy a boost tap for 20 bucks and think its got some uber boost holding power LOL

[WRXONP]

so you want more than 18 when u get "tuned"??

how it getting tuned? if it was reflashed i would just use the electronic solenoid

[soopersubaru]

control your hi performance engine with a proper computer (link,motec)

These cheap bits designed to increase boost just lead to premature engine failure..

Of course if you have heaps of cash and would rather buy or repair engines than have a proper computer tuned for the best performance.......Fit the cheap bits!!