Tell Buschur Racing they're been wrong for years, then. I have my boost source tapped at the compressor housing as well. I'm using a Hallman MBC, and its pretty much spike free. I never routed back up to the BOV on any of the three turbo cars I've owned.

FWIW, installing under the car was much easier for me. All you have to do is pull that small center access panel and use a flathead screwdriver to coax the factory lines off (hardest part of the whole thing). I followed the main line back, disconnected it at a T, and capped it there.

 

I only removed the overflow hose.... It dripped a few drops of coolant but that was all. What I did was to remove the electrical part that's bolted to the fan housing so the fan could come out and go back in easier....

 

In high psi applications you are supposed to tap into a pressure source after the throttle body (like between manifold/bov). You would most likely hold more boost to redline if you tapped into the bov hose instead. But go ahead and ask buschur if you don't trust me

 

The AMS instuctions say:

1. disconnect vacuum lines and plug nipples of stock MAF and turbo outlet

2. cut line between intake manifold and blow off valve insert the supplied "tee" and connect to the bottom of the MBC with vacuum line.

3. use vacuum tubing to hook up the side port of the boost controller to the open nipple of the waste gate actuator

Unfortunately their pictures do not really show these steps or even use the same nomenclature to identify the various lines, nipples, etc. They also used more words than I did and no bold or italics to make things clear enough.

Anyway, after reading these over and over and identifying all the components, I hooked it up so it would work and sketched the installtion I posted above. Hey, it might be wrong, but it does seem to work and it matches the instructions from AMS (after careful consideration)

peace

 

Here is a picture of the waste gate & turbo nipples/hoses

 

I have installed a joe-p mbc on my car both ways and found that with it off of the turbo nipple my boost would not hold steady and would fluctuate. I then t-ed off of the bov and it would shoot right up to 19psi and stay right there, very solid. By redline it would be at 18psi.

 

I did not try it with the connection direct to the turbo outlet nipple, but I looked at it again this morning and it's holding rock steady 20 p.s.i. This a.m. was ideal turbo weather, cool and slightly misty, light rain.

Noize & evoinit: you guys ought to try the hookup the way I show it in the sketch. It matches the directions by AMS and seems to work very well.

 

I called the people at AMS today and asked specifically the question about where to hook up the pressure line. His answer was definitely to hook the bottom of the MBC to a "tee" inserted in the line between the intake manifold and the BOV.
The other line goes to the wastegate actuator.

I was told not to hook up the pressure signal to the turbo housing......

I hope this clarifies the question about installing the MBC (at least the AMS MBC)...

 

As others explained, there is a lot more room to work with the fan out of the way. Here is what It looked like with the fan (and all the stuff that has to come out first) out.

 

Silver Evo8 great pics hope it is still working flawlessly for you I know it sucked when we where trying to get the directions correct in.Best of luck I also might go this route but I seem to be hitting 21psi then falling to 17 psi I guess I have good stock curve or my boost gauge is garbage?

 

Hm, I have a Greddy ProfecII, and I connected directly to the turbo outlet and and the actuator, as per the instruction that came with the controller.

Boost seems to hold relatively steady, with the exception of changing weather now, which requires me to play with the duty cycle % to keep from hitting the limiter..

Do you think it would make any difference to "T" it off instead?

 

It might make a difference because of the higher boost pressures that the EVO uses. Why not try the setup I explain above (tee off the intake to BOV hose)? It will not result in any sort of problem and it might cure the variations you are seeing....

 

I just got back from a great vacation from the British Virgin Islands (check out the picture, that's where we sateyed) . I'll let you know how the boost controller keeps working. BTW, I think you can still expect the boost to drop off because the car will not make boost once it is not under load... In other words, you'll make boost up to a point and then it drops off regardless. OTOH, you might be having some sort of problem. Which boost controller do you have?

 

Once you've disconnected the two hoses that go to what I'm guessing is the solenoid, do you just cap the solenoid off or remove it entirely? (This is on a car dynoflashed for the MBC.)

 

no need to remove or cap the solenoid nipples, except perhaps to avoid some trash from some how getting in there. After the hosea are disconnected and the MBC installed, the solenoid is totally out of the system.....