There has been a lot of speculation and misinformation regarding installation of a manual boost controller (MBC). Many people use the blow off valve (BOV) line as a pressure source. This is incorrect. Installing this way can cause many disruptions. Oldman originally posted this:
Quote:
Taking the pressure source from the j-pipe fitting has many benefits.
1. The main reason why alot of mbc instructions and some tech articles suggests to tap from the BOV line is because it's connected to the intake manifold, the argument is that this is more accurate because it's the same pressure the engine sees. In reality this is a non issue because the boost gauge is tap to the intake manifold no matter where you tap your mbc so there is no advantage in tapping the bov/manifold pressure as previously thought.
2. The proper functioning (opening and closing) of the bov depends greatly on the accuracy of the pressure in the vacuum hose you're thinking of tapping on or off boost so it's best to leave it connected directly to the manifold without any interference.
3. Tapping off the compressor/j-pipe offers the shortest vacuum hose route which greatly reduces the chance of boost spike.
4. In the case of boost leaks, tapping off the compressor/j-pipe will help prevent over boosting the turbo.
5. Hooking up a bleeder type mbc like the TurboXS standard mbc to the bov line will result in a vacuum leak as well as affect the working of the BOV.
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So basically, leave your BOV hose alone, and use the j-pipe nipple. For normal MBC's, the vertical nipple should be connected to the j-pipe. The horizontal nipple should be connected to the wastegate actuator. Remember to put the MBC as low as it can go, and adjust boost upwards as you go. Don't risk overboosting. Also make hoses as short as you can, to help increase boost response.
The spring (depending on adjustment) is in different states of compression. If it isn't compressed at all, it's not going to require very much pressure to push the ball up. Think of the ball like a door. The spring is holding the door shut. So depending on how much pressure is already on the spring, the ball is going to need just a hair more than exactly that exact amount of pressure to be pushed the opposite way. Once the boost overcomes the spring pressure, it enters the chamber and goes to the wastegate actuator. Here's some drawings I just came up with. Hopefully they'll help describe better visually what I cannot describe in words.
Depending on the type of boost controller you have, these specifics can differ. But basically the tighter the adjustment screw, the more boost needed to overcome it.
Tighter = You'll run more boost
Looser = You'll run stock boost
I understand my MS Paint skills are not too good, so here's some pictures of real life MBC hook-ups. The first picture is mine, excuse the silicone couplers. I'm redoing that whole compressor outlet pipe soon.
This one is easier to see the wastegate actuator hookup. This photo is supplied by DSMunknown. As you can see, it's a very simple install, it only takes a few minutes.
