I've searched for the past 45 min....

[Jazzie604]

Just to make sure I wasn't going to be asking too stupid of a question, I've been searching for the last 45 min to get a detailed description and still havent found one yet, so here it goes..

How exactly does a boost controller work? and does it always hold boost til the preset limit is reached or does it allow for little or no boost at light throttle? and just to double check the thought that I have, is the blow-off valve only for releasing pressure when the throttle closes? Like it says I'm a newbie, so help me out would ya?

[bluedragondsm]

im under the impresion that it slowly builds boost until the preset limit at full throttle

[imoore]

A boost controller works as such:

When the intake gets pressurized by the turbo, the source for the MBC too gets pressureized. Once the pressure reaches a set point, it has enough force to move the ball inside the MBC and therefore go through to the wastegate and then open the wastegate. The pressure required to move the ball is adjustable through a bolt/screw at the top of the MBC. The harder it is to move the ball, the higher the boost pressure will be achieved.

I'm sure there's something I'm missing but it's something that, after a few years, I take for granted knowing.

Refer to this diagram (available here (http://www.darklightning.com)):

http://membersites.namezero.com/jogauthi.nmu.edu/gi/mbc.jpg

[imoore]

I forgot about the BOV. The BOV opens when the pressure difference between the intake manifold (behind the throttle plate) and the intake track is great enough for the intake track pressure to overcome the spring in the BOV and vent the intake around. The BOV works under the same principal as a diaphram valve (I believe that's what it's called), which is the style valve used in high powered potato guns :D

[scotthidley]

In English:

The boost controller allows as much pressure to build as you set it to (of course the turbo doesn't go up to 12,224,343 psi). Regardless of throttle position (you can boost at partial throttle). Once the pressure hits the set limit, the controller will hold the pressure at that level (provided your still boosting).

The BOV just releases pressure, which most commonly is when you shift. It releases the pressure, momentarily lowering the engines power, making it easier on the clutch.