MBC won't let me boost past Spring Rate

AZN MK3

AZN MK3

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I was driving the other day, and to be honest I've never really looked at my boost gauge that much to see where I was at on my big single. Well I finally got around to look at it and say I was only boosting 10Psi. So that was my External Wastegate spring rate. Now I made my own Boost Controller from pipe fittings w/ a spring and ball bearing. I then went to go turn up the boost on the BC, took it for a spin and still say 10psi. I stopped and turned it up some more and took it for a spin. Still 10psi. I got the pressure source from the Compressor housing going to the Ball Bearing side of the BC and the other end to the wastegate, I left the top off for the vent just like I saw in the diagrams so what could be wrong? I inspected the BC that I made and tried blowing into the ball bearings side and a little air comes out, I go to tighten it and it shuts so I know I the BC is fine. A little help here guys would be much appreciated.. Thanks.
 
AZN MK3

AZN MK3

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bioskyline;1700452 said:
odd. faulty and or leaking boost gauge?
Click to expand...


I don't really feel a power increase, I did noticed it spooled quicker though. It's like the wastegate just want to keep opening at 10psi every time. I did almost have it completely closed at one point during my runs and it still says 10psi thus meaning the wastegate is opening at 10psi. Could it be the wastegate?
 
AZN MK3

AZN MK3

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bioskyline;1700477 said:
id say someting is wrong at the gate. unplug the gate completly and very carefull take it for a spin and see if it boosts more.
Click to expand...

Ok, so I drive it w/o a wastegate just to see if it will go beyond the spring rate? Should I plug up the nipple on the comp housing?

Also won't I hit FC since I don't have a wastegate.
 
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bioskyline

bioskyline

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powell river bc
yes plug the nipple on the comp housing. as for fuel cut yes and no, this is just to see if it will boost, not trying to set a record here, if you rev to high yes you will hit fuel cut, but a 4000-4500 rpm run should produce more than 10 psi on a large single.
 
AZN MK3

AZN MK3

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bioskyline;1700497 said:
yes plug the nipple on the comp housing. as for fuel cut yes and no, this is just to see if it will boost, not trying to set a record here, if you rev to high yes you will hit fuel cut, but a 4000-4500 rpm run should produce more than 10 psi on a large single.
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ok, it went past 10psi, I stopped it at 11.8 psi. It's digital btw. So it's the wastegate I believe is the culprit?
 
AZN MK3

AZN MK3

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MDCmotorsports;1700609 said:
Ugh.

Ill say it now and I'll say it again: IF YOU DON'T KNOW, DON'T POST.

Azn MK3... can you show us how you have the vacuum lines ran for the wastegate?
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Sorry about that, but yea I can post how I have it connected. It's similar but the vent tube is on the top of the wastegate, BC is T'd in between the pressure source and the wastegate. Again, the ball bearing is on the pressure side and the spring end is on the wastegate.
 

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AZN MK3

AZN MK3

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Feb 12, 2006
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MDCmotorsports;1700699 said:
So you ran a line WITHOUT the controller straight to the wastegate? Did the PSI go up or down?
Click to expand...

Before I got a boost controller I had a vaccum hose straight from the compressor to the wastegate. And it's a 10psi spring. Now when I go to put a boost controller and turn the dial it still says im boosting 10psi. I go to turn it up some more and still I get 10psi. The boost controller is almost fully closed and I still can't get past the spring rate.
 
AZN MK3

AZN MK3

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^^^ Weak spring? So I should go higher than a 10psi spring? I have the vac hose on the bottom half of the wastegate port. Left the port on top open for the vent like it shows in the diagram. So I know it's connected right, now why would a weak spring do that if I want to boost more?
 
AZN MK3

AZN MK3

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Ok, I tired swapping ports still did it. I took the wastegate off and decided to add another spring to it. Now it says I'm boosting at 13psi, so I guess I'll leave it there since fuel cut is right around the corner... I still don't know what could have been the problem, so I'll just not run a boost controller now since it's at 13. well thanks again guys... When I tune it for more Psi's I'll see if it was because the spring I had was too weak or not... Thanks
 
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