Does anyone have a picture of their installation on an Audi 5000?
I read on http://www.gtquattro.com/boostin.html: "By use of a pressure regulator you can bypass the frequency valve which regulates pressure to control the wastegate. A pressure regulator is installed in place of the frequency valve to permit addition of regulated boost pressure on the top side of the WG diaphragm... The input pressure is taken from the boost side of the Pressure transducer, and the output side is directed to the wastegate control port."

I'm assuming the wastegate control port is the top nipple on the wastegate in the picture... Is this right? I bought a Voodoo III MBC on ebay (http://cgi.ebay.com/ebaymotors/ws/eB...ht_2520wt_1161) and I just want to know how to throw it in the mix. Do I just disconnect the boost control solenoid entirely (block off the lines and leave electrically plugged in) and run intake manifold boost pressure to the MBC then run the MBC to the top wastegate nipple?

Thanks all.

 

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I see from ETKA that there is a reference to the fatter intake manifold line ("pressure controlline") going to the bottom of the wastegate. Is that the line I need to use the Manual boost control with, you reckon? It gets boost and SJM states that you should pinch it off and do a test drive to check for max boost and fuel cut-out. Sounds like the right idea to me. The line I was referring to previously was #40 known as "hose" which both WG lines use...

Just looking for input thanks


PS The barb fittings are 6mm (.2362 inch) on the voodoo III and the steel banjo for the control line is .488 inches but it was a bit tight for the dial calipers so it may be off. The top nipple on the WG still seems more logical if going on hose sizing alone.

 

I finally found the answer...

On a totally separate forum from audi, post #14:
http://www.forums.turbobricks.com/sh...ad.php?t=48461


"The nipple on top of the thing is so that you can apply boost to the topside of the diaphragm holding the gate closed to the point when your boost controller says 'enough' and the gate is allowed to open. This is very effective and smooth."

 

in this post at least...

I have created a diagram using ETKA images and the MBC installed on the wastegate. Please check my image and let me know if it looks proper....as I'm still a bit unsure of the routing of lines. The factory setup had both #34 hoseclamps on the same hose from the wastegate lower port to the intake manifold. Thanks.

 

which I believe is the correct set up. I got the idea from Autospeed's writeup. I'm just not entirely sure that the top nipple should be open to atmosphere but it seems proper I guess. I welcome any input AT ALL, WHATSOEVER, please. Haha thanks.

The write up comes from
http://autospeed.com/cms/title_The-A...8/article.html

 

"I am an engineer..."

Yah, I can tell - you're thinking about this way too hard!

Right now the three hoses on the N75 valve are regulating boost pressure, one goes to the manifold, one to the intake boot, and one to the top of the wastegate.

Manifold pressure = WG opens against spring plus boost pressure.
Intake boot pressure = WG opens against spring only.

I'm pretty sure you connect the manifold and wastegate lines to your schrapnel ****, and plug the one to the intake boot and twist away, but then again I've never messed with stock setup to find out.

Get a real boost gauge before you put it in, run premium only from there on out, and don't go over 6 PSI on a stock ECU.

 

Thanks rally, ya ur right I've been trying to wrap my mind around every possible setup ever since I ordered the mbc hah. I appreciate the info. I have an aftermarket gauge in already. The car is TAP chipped and the gate has the spring too. I don't have the n75 but an older boost solenoid with a different p/n I've seen the mbc diagram for the n75 and I will take another look at it. Thanks again.

 

EBC's or MBC's just read on...
---------------------------
Trust me Paul #1, I have done alot of research on this and I have a brand new TIAL 44 from Extreme PSI sitting right in front of me with instructions to use only the side port and VTA the top port with MBC, on the top of the instruction sheet there is a *NOTE* For electronic boost controller installation, use the manufacture's instruction.

Let's break it down into different situations for better understanding.

1. With both ports open, much like leave the fitting on an internal wastegate fitting open, the wastegate is suppose to hold approximately 2x the spring pressure (its ability to hold back exhaust pressure). Example, 14psi spring = 28ish psi of intake pressure.

2. No boost controllers but both top and bottom connected to straight intake pressure, the result is the same as #1, 28psi.

3. No boost controller but with side port connected to intake pressure signal and top port VTA, much like running no MBC with an internal wastegate, the wastegate will hold exact the spring pressure. Example 14psi spring = 14 psi of intake pressure.

4. EBC or bleeder MBC, side port sees intake pressure (which will result in #3), the outlet of EBC or bleeder connects to the top port, for every psi the top port sees, there is one PSI increase in intake pressure. Note, a bleeder MBC will work in reverse in adjustment as in an internal gate environment, the more pressure you bleed off, the less the top port sees, the lower the boost level.

5. Ball/spring MBC, top port VTA and outlet of MBC connects to the side port. No pressure will be sent to the side port until the spring pressure in the MBC is overcomed, just like an internal setup. The reaon a ball/spring MBC doesn't work with the top port is because you have no control over exactly how much pressure to send, either you get nothing or you get everything, unlike an EBC or bleeder MBC. Let's put it in examples of running a ball and spring mbc using the TIAL instruction, assuming the wastegate spring pressure is 14psi.

A. MBC all the way out (no pressure on the ball), top and bottom port sees the same pressure, you get #2, 28psi.

B. MBC all the way in (max pressure on the ball), nothing gets sent to the top port, you get #3, 14psi.

So far so good but the problem is contolling boost pressure in between.

C. MBC set to anything between 0-14psi, as soon as the ball gives, the top port will immediately see the same pressure as the side port, you'll always get #2, 28psi.

D. MBC set to anything 14psi+, the top port will never see anything at all because the side port will open the wastegate before the ball is overcome, you'll always get #3, 14psi.

Hope my explanation isn't too confusing.

Lastly, to get away with using a smaller wastegate spring while trying to run higher pressure, you leave the side port open, 28psi, then for every psi you add to the top port, you get 2psi more in intake pressure.
---------------- Post #2 @

http://www.dsmtuners.com/forums/bolt...e-install.html

As you can see, Autospeed was right on the motherfreakin money. This dsmtuner post is like gold. I will use my "Option B" layout for the installation.

 

I'm not sure how kindly CIS will take to having pressure bled off to atmosphere instead of back into the intake. Let us know how it goes.