Theory regarding boost taper problem:
09-02-2004, 06:29 PM
#42
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I'm "all about" exorcising the taper from my setup ;)
Thats why people like you need people like me. I don't hesitate to screw around with stuff, plus I share what I find out, good or bad 
09-03-2004, 01:33 AM
#45
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AMS to a local stage 5 owner to do the same thing
He had a shop tighten his wastegates atleast on 2 instances. It got to the point that the shop was uncomfortable making the adjustments even if Mark at AMS insisted it was ok. I believe they tighted the wastegates about 10 threads on each side.
09-03-2004, 07:45 AM
#47
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Thinking out loud .... --->
If the MBC maintains <b>constant</b> pressure on the WG actuator to set max boost, then the WG will be pushed open further as the TIP rises with increasing engine speed at WOT. If the actuator rods are shortened, the MBC must be reset to hold the same max boost, and the WG will again open further with increasing TIP. I don't believe this will solve the problem.
The above premise about <b>constant</b> MBC pressure is debatable, since ball valves typically require a higher "cracking" pressure to open compared to the flow pressure to just keep them open. And there will be some flow either through the MBC bleed hole or the N75, depending on the installation. I have the installation shown in the picture but haven't yet analyzed the observed pressure patterns. They're surely complex.
<img src="http://209.128.70.155/ManBoostCtrl2.jpg">
The above premise about <b>constant</b> MBC pressure is debatable, since ball valves typically require a higher "cracking" pressure to open compared to the flow pressure to just keep them open. And there will be some flow either through the MBC bleed hole or the N75, depending on the installation. I have the installation shown in the picture but haven't yet analyzed the observed pressure patterns. They're surely complex.
<img src="http://209.128.70.155/ManBoostCtrl2.jpg">
09-03-2004, 07:58 PM
#48
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Nice illustration! I already purchased an EBC...
Hopefully that, combined with the WG rod tweak, will greatly reduce this. If not Jacob has some higher rate actuators he's working on.
09-03-2004, 08:26 PM
#50
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I would exhaust all/most other tests before resorting to that. If N75 or other means can...
... maintain flat boost to redline, then the WG spring rate is not likely the issue.
Besides, I can't imagine it's easy to get in there and physically access those WG actuator arms, is it?!
Besides, I can't imagine it's easy to get in there and physically access those WG actuator arms, is it?!