hey,

ive got a vibrant MBC on my machine and no matter how much i turn it "up" i cannot get much more then 10psi, if cap off the waste gate feed the turbo hits like a freight train to 20psi before i have time to get off the throttle. obviously the turbo is working well and building boost, the waste gate is obviously staying shut, so the only thing i can think of is the boost controller. I have double checked the line orientation to make sure its correct and it is.

im thinking about porting the orifice on the side of the body that lets the pressure bleed off to hopefully remedy these issues, anyone else had problems like this with a MBC of any kind?

http://vibrantperformance.com/catalo...Path=1022_1278

 

how do you have it plumbed in? is it between the turbo and WG or is it Teed in between the turbo and WG?

 

pressure signal is fed in from the bottom and signal to the WG is on the side via vibrant instructions. its plumbed in via port on the compressor housing on its own boost circuit

 

If this is on a stock engine and turbo then I wouldn't worry about it.Stick with 10.
You will have to worry about the engine if you keep hitting 20 psi though.

 

Stupid question... do you have the right spring inside?

 

stock s5 JDM keg with a 60-1 to4b hybrid, ideally i'd like to run 17-18psi, 23psi will come later with a billet compressor wheel, 360 thrust bearing, standalone, engine build, and water/meth injection

 

it doesnt use a spring

 

so its not in place of the S5 boost control solenoid?

 

..On your wastegate....lol!

 

no the engine is running stripped down s4 harness, s4 ecu rtek 1.8, and apexi neo w/ 800/1kcc injectors backed by an AEM 320

 

?

 

With the valve fully tightened, can you still blow through it? At anything other than 'fully sealed' you're going to get some pressure bleeding through the controller. It takes very little pressure to operate the stock wastegate.

I'd suggest either an electronic boost controller or a generic, adjustable t04b wastegate actuator.

On a side note, I think a 60-1 wheel efficiency at 17psi would be pretty poor. Is the turbine clipped and are you monitoring AIT's?

 

how do you have it plumbed in? if its like the top, you need a boost controller, if its like the bottom then you should consider redoing it.

t/c = turbo charger
b/c = boost controller
act = wastegate actuator

 

get a spring type mbc those bleed off ones are crap. i'd recommend a hallman mbc they are awesome quality i've been using mine for years. they might be a little pricier than some others but you get what you pay for. if money is no object get an electronic bc

 

for some reason i doubt it is installed per the instructions.

or

the internals are defective. remove the adjustment screw and make sure the needle is undamaged and actually present as in the picture.

 

fully closed it runs 5-6psi of boost

i've been thinking about swapping on a t04b actuator just because the current actuator is very old, i think i'll be switching to a ball-spring MBC for the added boost response

i have not been monitoring IAT's

 

checked and cleaned it yesterday

 

I wonder if i could make my own homebrew electronic boost controller....

Parts list:
pressure switch
air solenoid
relay
potentiometer

 

Now I see how it works. The design is complete garbage for boost response, though. As you mentioned before, opening up the "exhaust port" might allow it to work better. To definitely make it work, you'd need to open up the top half of the vertical pathway and re-make the pin to seat in there. Hardly worth the effort.

An EBC or ball/spring MBC will hold boost better. Upgraded actuator won't be necessary if you have a better boost controller.

 

It's a simple system and pretty much identical to one on the stock S5 turbo. You're just trying to change what pressure it actuates at.

If you're building one yourself, the difficult part is finding an accurate pressure switch that operates on 12vdc in the pressure range you're looking for.

Maybe a PWM controller for the solenoid so the wastegate doesn't do this during every pull.

 

ever thought about using a pressure switch from a aux injection kit (or just buy the switch outright

PWM controller?

 

http://www.ebay.com/itm/AUTO-METER-3241-WARNING-LIGHT-PRESSURE-SWITCH-18-PSI-NO-RESERVE-/320878922542?pt=Motors_Car_Truck_Parts_Accessories&hash=item4ab5dfcb2e&vxp=mtr
http://www.ebay.com/itm/Boost-Control-Solenoid-valve-BCS-MAC-35A-AAA-DDBA-1BA-turbo-PWM-EMS-ECU-/230925205680?pt=Motors_Car_Truck_Parts_Accessories&hash=item35c43700b0&vxp=mtr
http://www.ebay.com/itm/New-12V-DC-40A-AMP-Car-Auto-AUTOMOTIVE-Relay-Socket-4Pin-4-Wire-Harness-Black-/190803516133?pt=US_Relays_Sensors&hash=item2c6cc69ae5
not adjustable, you'd just have to change the pressure sensor for one with a different value

 

Ditch that crappy boost controller. Get a hallman if you want an mbc...better yet, I will sell you one if you want.

 

i don't know if i'd trust an engine to a $4 relay that is acting as a duty cycle solenoid actuator, talk about points burning out in short order followed by an overboost condition.. i suppose you could just change the relay every oil change and you might be ok.

 

If you have a solenoid that is 'normally open', losing power won't be completely devastating. Unless you're racing for pinks. But I agree with your point about the relay not being meant for that duty cycle/number of cycles. Wonder how many people trust their pump to the same relay.

It's something to smooth out the wastegate signal by regulating how the solenoid opens and closed. The switch is on/off, so the wastegate would keep getting full pressure, open the wastegate 100%, switch turns off and closes 100%. Repeat multiple times during a full throttle pull. Reminded me of the monkey.

Maybe that's why the S5 wastegate arms wear out so much faster?

My point, which I didn't actually say, was that by the time you cobble something together, you easily could've bought a good EBC. They already have functions like multiple settings and gain control that are a lot hassle to design from scratch.