MBC underboosting
05-07-13, 04:07 PM
#1
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MBC underboosting
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
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
05-07-13, 04:23 PM
#2
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how do you have it plumbed in? is it between the turbo and WG or is it Teed in between the turbo and WG?
05-07-13, 04:30 PM
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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
05-07-13, 11:10 PM
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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.
You will have to worry about the engine if you keep hitting 20 psi though.
05-08-13, 08:47 AM
#6
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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
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05-08-13, 09:44 AM
#8
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..On your wastegate....lol!
05-08-13, 01:04 PM
#12
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?
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?
05-08-13, 01:20 PM
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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
t/c = turbo charger
b/c = boost controller
act = wastegate actuator
05-08-13, 01:33 PM
#14
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
05-08-13, 01:42 PM
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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?
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?
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
05-08-13, 02:34 PM
#18
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I wonder if i could make my own homebrew electronic boost controller....
Parts list:
pressure switch
air solenoid
relay
potentiometer
Parts list:
pressure switch
air solenoid
relay
potentiometer
05-08-13, 02:48 PM
#19
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.
An EBC or ball/spring MBC will hold boost better. Upgraded actuator won't be necessary if you have a better boost controller.
05-08-13, 02:57 PM
#20
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.
05-08-13, 06:57 PM
#21
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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.
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.
PWM controller?
05-08-13, 07:11 PM
#22
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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
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
05-09-13, 04:27 PM
#24
Auto Meter 3241 Warning Light Pressure Switch 18 PSI No Reserve | eBay
Boost Control Solenoid Valve BCS Mac 35A AAA Ddba 1BA Turbo PWM EMS ECU | eBay
New 12V DC 40A Amp Car Auto Automotive Relay Socket 4pin 4 Wire Harness Black | eBay
not adjustable, you'd just have to change the pressure sensor for one with a different value
Boost Control Solenoid Valve BCS Mac 35A AAA Ddba 1BA Turbo PWM EMS ECU | eBay
New 12V DC 40A Amp Car Auto Automotive Relay Socket 4pin 4 Wire Harness Black | eBay
not adjustable, you'd just have to change the pressure sensor for one with a different value
Last edited by RotaryEvolution; 05-09-13 at 04:30 PM.
05-09-13, 04:56 PM
#25
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.