SAMCRO08

I did some research on here and google about boost creep issues but i want to get some advice about my setup

Setup: Go-autoworks mini ram manifold
Comp t3/t4 turbo billet wheel
3 inch downpipe, 2.5" cat, 3 inch cat back
2.5 inch ic piping
new but old school turbonetics delta gate wastegate
Grimmspeed MBC
Built B18C1 with skunk 2 tuner stage 2 cams


I was street tuning it last night and on the boost controllers lowest setting which is turned all the way out, grimmspeed says that is stock wastegate setting or 7psi

From a dig or any kind of rolling start, the boost pressure will stay at 7 psi until right around 5,000 rpm and then start climbing, after vtec it gets higher and hondata will reach boost cut

so the questions come to mind?

1.) are the mbc vaccum lines close enough to the wastegate? the mbc is mounted on the driver frame rail

2.) is this wastegate efficent enough? I read stories about the turbonetics delta gate having creep issues last night

3.) is my boost source incorrect? I do have the turbo tapped on the housing for the boost source, should i use the manifold as a source instead?

any advice would be appreciated

kyden

why not remove the boost controller and see if your problems go away?. that would have been the first thing to do.

SAMCRO08

I had the setup running just off wastegate pressure before and i would hold boost at 7 psi and not go past. but i'm trying to run more boost pressure

Muckman

iTrader: (2)

If you get no creep without the MBC then the problem is clearly related to the MBC. How do you have it plumbed? And how much boost creep are we talking about?

SAMCRO08

Muckman: What do you mean by plumbed? im getting about 8-12 pounds of extra creep till 8000 rpm

tron_

He means how/where are the lines going to and from the MBC?

Muckman

iTrader: (2)

Hoses, pipes, tubes. Show us how its hooked up.

SAMCRO08

sry sry.. i dont have a pic with me right now.. but the mbc sits on the frame rail on the driver side. The bottom hose of the mbc goes to the turbo tap and the side hose of the mbc goes to the side of the wastegate. I have an edelbrock manifold with front mount intercooler tr8 from treadstone and 2.5 inch piping from turbo to tbody.

TheShodan

iTrader: (14)

Ah... The reference to the compressor cover might be a bit too strong.. that's happened before. Move the hose that's going to the compressor cover to another reference point like the intake manifold as its vacuum reference instead.

SAMCRO08

The Shodan: I was thinking that too, but im just leary on this wastegate

TheShodan

iTrader: (14)

I remember the Deltagates, as they were the only gates that actually were adjustable, and could go from 7-9 psi from the top adjustment nut.

It could actually be BOTH the reference point and the gate as the problem, as the valve may have experienced different fuels and because of its makeup (and age) may not be opening when it should.

1) Change the reference point to the Intake manifold.... Test on a drive, see what it does..


2) If no change, then make sure that adjustment nut on top of the Deltagate is down all the way. Test on a drive again, see what it does.

3) If STILL no change, look at the valve for a change in color in the wastegate valve stem itself. if it looks a bit cooper-ish in color, that means different fuels have been used (Race gas, Alcohol, etc from the previous owners) and may have affected the valve itself on a metallurgical level. If that's the case, throw it out, and get a TiAL or turbosmart in a 2 bolt flange. (Yes, TiAL still makes 2-bolts)

4) Being Leary won't solve the problem... Gotta make some moves to solve issues. Hop to it..

SAMCRO08

sir yes shodan sir lol

wantboost

iTrader: (2)

The mbc is the problem 9 times out of 10. It's basic, unintelligent boost control that can't control creep

Remove it and run a line from the compressor housing to your wastegate and see if it goes away. I'm betting it will. Also that 2.5" cat on a 3" system could cause some issues as well

TheShodan

iTrader: (14)

HUH? Its fine. Especially if its a Grimmspeed, GoFastBits or Hallman. (you must not know about that company in the Subie world). those are the most STABLE manual controllers ever. They hold steadfast and easily are used to make 30-40psi of boost pressure STEADY. Not like the TurboXS controllers in which the mechanism shifts while during boost.

Its simply a boost reference point. the controller itself is fine. I've bet my life on the Grimmspeed before. Has never failed yet.

wantboost

iTrader: (2)

I know about hallman and gfb. I have a few gfb parts laying around

The problem is mbcs aren't "intelligent" boost control. You can set it for a certain psi but it cannot control creep and keep boost at the target level if creep occurs

TheShodan

iTrader: (14)

Yes, but that's what makes it so nice and simple. Change your boost vacuum reference point and problem is solved. No electrical solenoids or other nonsense to worry about..A case where ignorance is bliss.. *sigh* ahhh the good ole days.

hybrdthry911

I completely disagree and would say the exact opposite. Boost controllers don't "control" creep. If you didn't have any boost creep problems running on the wastegate spring then the only creep a boost controller would need to control is the boost creep it is causing itself.

9 times out of 10 a MBC causes boost creep problems? I've never seen someone install a manual controller and suddenly have boost creep issues. If you want to run one single boost level then you don't need "intelligent" boost control, MBC will work fine.

wantboost

iTrader: (2)

The problem is a lot of people using mbcs use the compressor housing as the pressure reference. There's a lot of pulsation and fluctuations in the compressor volute which causes issues not only with mbcs but with ebcs as well.

All I'm saying (like you) is that if you had no creep issues running off the wg spring then install an mbc and then at some point have creep (mostly weather related, i.e. very cold temps) then the mbc has knoe way of "knowing" what its targrt boost level is and cannot lower boost should it "creep"

Ebcs, especially ones run by ecus and standalones take a lot of data into account to control target boodt pressure and the boost pressure ramp up time to targrt boost. Things like barometric pressure, iats, engine load, tps, rpm and some even measure humidity. This leads to overly precise control of the target pressure and should pressure levels exceed target boost then the ecu knows what measures to take to try and lower. Like modulating the solenoid cycles, modulating solenoid frequency, and in some cases closing the solenoid all together, like if the boost pressure reaches the boost cut value

TheShodan

iTrader: (14)

Yeah, but if that was the case where it worked in a perfect world, you wouldn't be seeing all these "boost creep" threads using a MAC solenoid and Hondata S300 like we have been the last few months.

MBCs work for their particular purpose. Its like what Mr. Scott on Star Trek said once: "The more you overwork the plumbing, the easier it is to stop-up the drain.

wantboost

iTrader: (2)

That's simple. The boost tables were tuned at warmer temperatures. Now that it's cooling off the tables are off. We'll see more threads like this pop up as it gets even colder

Kinda like when summer is in full swing overheating threads pop up like stds. I can always tell what time of yesr it is by the threads people post on HT lol

TheShodan

iTrader: (14)

Touche'. many of even the EBCs people don't readjust for the cooler, denser air.

wantboost

iTrader: (2)

Yea and they don't know why all of the sudden they have overboosting issues

It's even worse with mbcs as the boost will just continue to climb until eventually you hit boost cut(if you have one setup, which everyone should) (just like the OP is describing)

To the OP, the compressor housing is a bad spot for a boost signal. There's a lot of turbulence in the compressor volute as it compresses the air, which causes varying pressure waves and pressure levels. Move the signal to the intake manifold after the throttle body, you'll notice a much smoother boost curve and the mbc will better control boost because it's not getting a random pressure signal like it does at the compressor housing.

Another thing is does your mbc have a stainless steel or ceramic ball? Sometimes swapping to a ceramic ball will help with creep as the reduced weight of the ball allows it to respond much quicker to fluctuations in boost pressure. Sometimes it will even eliminate creep but that varies from setup to setup and with things like elevation, temperature, and humidity.

TheShodan

iTrader: (14)

Grimmspeed already uses a ceramic ball. The MBC is good. trust me.

wantboost

iTrader: (2)

I know. I might suggest the OP pull the mbc apart and clean all of the components, if any oil or debris gets inside the controller body it could block off the bleed port and cause issues with the ball travelling inside the unit. Leading to a failure of the units ability to accurately regulate boost pressure. All of which could be causing some of his issues

Especially since he had the pressure source on the compressor housing, it could of ingested oil, debris, etc. Especially if a proper filter wasn't being used

SAMCRO08

i took you guys advice and the intake manifold source seemed to help issues alot more. I pluged off the source on the turbo and called it a day