ok guys how many of you have your mbc inline? How many of you have the non ball bearing side going to the wg and the ball bearing side t'd off between the intake mani and BOV. Finally how many of you have the ball bearing side t'd off between the turbo outlet and the wg with the non ball bearing side vented off into the atmosphere?

I always under the impression you could only put the MBC on one way?

Yeah, a ball/spring MBC can only work properly one way. The ball end of the MBC, usually the directly opposite end of the adjustment knob/screw, ect, goes to the manifold pressure source, turbo compressor housing, ect.
Then the other barb goes to the wastegate actuator.

Your last way of conneting that up would be like using it as a generic "bleed" type boost contorller. This pretty much defeats the purpose of the ball/spring type MBC. Bleed type controllers create boost lag by prematurly opening the wastegate. The ball/spring type keeps pressure away from the wastegate until the desired pressure is reached to push the ball off the seat. After this happens, the ball acts as a pressure regulator going to the wastegate.

Yup that is how i have mine. Ball towards the source.

well I went back to an inline setup, where as the ball bearing side goes to the turbo outlet and the non ball bearing side goes to the wg. It worked and I can control boost again. Anyone else have it hooked up differently? I know Dan does and it works for him.

Well that was your problem then...Ball/spring MBC's are not intended to be used as bleeders..Once the "set" amount of pressure lifts the ball off of its seat, pressure exscapes to the wastegate. But after that happens, the ball needs to see some pressure on the wastegate side of the line, to keep a more "regulated" flow of air passing the ball. If there is no resistance on the spring side(ie open to air), then it will just pop open and be very, very hard to regulate air pressure, eg boost pressure, because it makes it very sensitve on the adjustment screw. I suppose if you could try different springs with varying tensions, you could prob get it to work a bit better. A really simple bleeder boost control setup is just to use a really small plastic vac T fitting in the WG line..The open end of the T is going to nothing(open air), and bleeds off air to the WG. Doubling up or using a larger hole in the T end, gives more boost. Bleeder type BC's are def not the best way to do it. YOu can get bad spikes, turbo lag, and boost drop off in higher rpm. I never had really good luck with MBC's when running higher boost on a lower psi wastegate spring..Generally, when going 7-10 psi over the WG spring setting with a MBC, spiking can get worse..and generally more sloppy boost control. This is where an electronic BC is much more reliable.

YOu know if you wanted to you could just put a restrictor in there. Take the nipple off of a spark plug and jam it into the line going to the wastegate. You will get higher boost level. Totally gheto, but does work.
Subaru uses a similar setup on thier FBC. It is obviouly not a spark plug restrictor, but it is the same concept. The wastegate on a wrx is set at about 7-8 psi, with the restrictor out FBC working the car will still only see like 10 psi. With the FBC and restrictor out, they see about 7 psi, with the restrictor FBC out and restrictor in they still only see like 10 psi. Everything installed correctly they see 14.xx psi. The only reason I know this is my buddy has a wrx we had been fighting with this problem. He was only seeing at max 10 psi, we changed out everything from the FBC to the actual lines. Turned out to be the stupid restrictor that we were missing.

Originally posted by DSMRoadster
well I went back to an inline setup
Anyone else have it hooked up differently? I know Dan does and it works for him.

I always used RRE MBCs. I don't think they're ball-and-spring type, pretty sure they are bleeder type. However, I really don't think it matters? The important thing is that the ball faces the turbo outlet nipple (if installed inline), or the tee (if installed in bleeder format), and that you use a restrictor.




This is how I have done it with a BLEED type MBC. With an electronic boost controller, I just replaced the tee and the line to the MBC with the EBC's boost solenoid. You'll notice the solenoid has a tiny hole in it which allows it to bleed off air just like an MBC. I never had any creep, spiking, or lag, it was always rock solid to 0.5 psi no matter whether I set it to 5psi or 22psi. YMMV, especially if you use cheapo MBC's, and the wrong size restrictor.

well I realized the turboxs boost controller is a bleeder type, and I hooked up exactly like Dan's. Let me tell you that this is the best way to hook it up. No creeps and no spikes. Holds steady and strong.