Here's my experience with the Hallman (which I had in my Talon for almost two years and my Stealth for four months. I never got any boost spikes in my Stealth but that could be partly due to the fact that stock turbos aren't capable of maintaining boost at higher RPMs. My 15G turbos will be in any day now so it remains to be seen if boost spikes will appear with the bigger turbos. On the Talon (which had a pretty big turbo stock), the guage would hit 16 psi for a split second before settling down to the 15 psi I was aiming for.
I too have heard talk about atmospheric conditions causing the need for constant adjustment but I never experienced this. I set it and forget it. If you understand the way the Hallamn works, I don't see how atmospheric conditions could affect it. There is basically a ball which is held against a hole by a spring, and when enough boost pressure builds on the other side of the hole to overcome the spring pressure the boost moves the ball allowing the pressure to go to the waste gates. The tension on the spring is adjusted by a bolt which you turn in or out to raise or lower the amount of boost pressure which is necessary to push past the ball and open the wastegates. Think about it: How could humidity or barometric pressure affect the tension on that spring? I guess temperature could affect how resilient the metal in the spring is but I've never noted a difference on my SPI boost gauge. I don't know how the Extreme XBC works so I can't comment on it other than the fact that most of the DSM guys prefer the Hallman over the Extreme.
Maybe what people notice with changing atmospheric conditions is the way their car REACTS to changing atmospheric conditions under higher boost. I had the Hallman in my Talon, which is more susceptible to fuel cut than the Stealth. I would notice that when it was cold out the car would hit fuel cut at a lower boost pressure than when it was warm out, so I would have to back off on the boost a bit to compensate. This again is a condition of the CAR'S reaction to the boost, not that the Hallman wasn't holding the boost constant.
Oh yeah, I'm not a Hallman salesman, just a satisfied customer!
Make sure you check out their web site for more info.
Let me start off by saying that I'm not sure about the Hallman, so someone with experience with that particular BC step up...
I have the Extreme XBC installed right now (waiting on the Apex S-AVC-R to show up) and I have 1 major problem with it. It is basically a glorified bleeder valve, albeit one that won't leak or change settings unless you make it. I don't have problems with the quality of the unit, but the main problem with the XBC is its dependence on external variables. That is, you can spend all day tuning in the XBC to actuate the BS at exactly 15 psi, but as soon as external variables change you have to tune it in again. By external variables I mean air temp, humidity, barometric pressure, elevation, etc.
The problem is that all the BC does is bleed off pressure from the actuator. It doesn't actually sense boost and react (like most EBCs). I heard somewhere that the Hallman uses a regulator of some sort instead of bleeding the pressure to the actuator, but I have no experience there and hence no comment.
My suggestion is to do a lot of research before you purchase a manual boost controller, cause if you get rather serious about tuning the car you may find yourself in the market for an EBC when you get fed up with the MBC (oh and BTW: I will be selling my XBC for practically nothing).
'93 RT TT
That has experienced overboost to 20psi with a manual boost controller (extreme xbc)
It is a pain to feather the accelerator while keeping your eye on your boost guage the whole time.. I don't remember the last time I had the car at WOT in 1, 2, and 3..
Thanks for the info.. The Hallman and the XBC are completely different from my experience and what you said. The XBC just bleeds off pressure of the line (like a bleeder valve). So say it takes 9psi for the actuator to actuate the wastegates, you can bleed some of that pressure off and effectively change the amount of pressure needed for the actuator to see 9psi. This is very different than the Hallman from your information as the Hallman actually senses boost (by ball and spring) and then actuates the BS at the right time. This is more like a manual EBC (because it isn't just bleeding pressure like the XBC and others).
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