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Old 09-07-2005, 07:53 AM   #21
ride5000
Scooby Guru
 
Member#: 32792
Join Date: Feb 2003
Chapter/Region: NESIC
Location: lincoln, ri
Vehicle:
2003 GGA MBP
12.9 / 105+

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Quote:
Originally Posted by MRF582
great thread. will any ball-spring MBC work? of course it won't be cockpit adjustable but that's ok. are the E-bay $20 MBCs a complete waste of money?
well, for <20 bucks you could go to home depot and cobble one together yourself. what is important is the seat of the ball which can be ascertained by attempting to blow through the mbc backwards, while closed. obviously a good seal will allow only a tiny (preferably zero) amount of reverse flow.

if you can't be bothered to DIY you can go for the ebay specials, but i have no experience with them so i can't help you much there.

Quote:
is it necessary to use a 1watt 10-ohm resistor in line with the GM BCS?
no i have not had any issues leaving the resistor out.

Quote:
if i were to use a cheap E-bay MBC, is there a chance of getting boost spikes? the protection against boost spikes is a result of a high-quality MBC or is it b/c of the inherent design of this system?
ball and spring mbcs are second only to bleeder types WRT spiking. if you use tubing/fittings that are too small in diameter, or too long in length, spiking is more of an issue, but generally only the most expensive EBC systems out there (avcr, oem ecu) will have a more stable/predictable response.

Quote:
what's better to use. open loop boost control or closed loop? i have an 04 and remember reading somewhere that open loop boost control was the way to go. any comments on that?
honestly closed loop boost control via the utec would PROBABLY be a little bit better as it attempts to more closely control the boost via feedback from the MAP sensor. thing is, it takes more time to set up and for the rough "ramp" curve that i have set up the open loop boost control was sufficient. it does vary more WRT ambient temperature than closed loop does, but the high level clamp provided by the MBC is surprisingly absolute. i dicked around with CLB for a while but i grew impatient.

as far as one being preferable to the other on the 04s, are you sure you're not confusing open and closed loop boost control with open or closed loop fuel control? the post bugeyes should DEFINITELY use open loop fueling to combat the crossover delay programmed in those later ecus

lmk if you have any more questions.

hth
ken
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