DIY MBC boost controller

kidwired · Post by **kidwired** » Sun Apr 17, 2005 6:02 am

I found this for those wanting to build your own MBC as I may do.

http://www.geocities.com/chmwatson/FAQs/mbc.html

order everything here.
http://www.mcmaster.com/

they might even have the stuff for coffee cups.

Warp3 · Post by **Warp3** » Mon Apr 18, 2005 9:36 pm

That's the instructions I used to build the MBC that my RX currently has installed (which will be making its way to the Legacy at some point).

The only difference I would suggest is to go to the plumbing department and buy a brass "bushing" which is pretty much the exact same thing they have you making from the male-to-male coupler and tap set in those instructions and the bushing costs about the same as the coupler does anyway (adjusting the size of the bolt to make sure it matches the inside threads of the coupling of course). In fact, in my build, I used the brass bushing that came with one of my Autometer gauges that I didn't end up needing for my gauge install, but happened to be the right size for this.

vrg3 · Post by **vrg3** » Mon Apr 18, 2005 9:53 pm

I usually just solder a nut to the end of the tee.

And I actually also had success just retapping the 1/4" NPT threads to a regular parallel thread... I think it might have been 1/2"-20 or maybe 7/16"-20.

IronMonkeyL255 · Post by **IronMonkeyL255** » Mon Apr 18, 2005 9:54 pm

And I believe that someone mentioned that you could put another ball bearing at the other end of the spring for added safety. That way, it would keep the car from boosting uncontrollably if the bolt backed all the way out.

I have that page saved. I plan on making one once I get a boost gauge.

gustavohuber · Post by **gustavohuber** » Tue Apr 19, 2005 12:11 am

hmm, maybe I can use that to control the rate of freon leakage from my AC system. damned n/a engine really minimizes my chances for making cool gadgets.

Project_Legacy · Post by **Project_Legacy** » Tue Apr 19, 2005 2:33 am

kool. thanks for the info yo. ill probably be doing this sometime soon as well. i have a question on this though. does the MBC only replace the Boost Control Solenoid and not the other 2 sensors that are on the passenger side strut tower? or does it replace all of it? im wondering because i bought those three sensors all together and the wires were cut.......... any help would be appreciated. thanks

vrg3 · Post by **vrg3** » Tue Apr 19, 2005 2:53 am

It replaces the boost control solenoid only.

Project_Legacy · Post by **Project_Legacy** » Tue Apr 19, 2005 3:20 am

ok kool. thanks a lot.

kidwired · Post by **kidwired** » Tue Apr 19, 2005 3:26 am

yea, it replaces but doesnt the 3rd (elevation thingy) not work anymore once you remove the other lines? may as well just cap it off both on the black box and the selenoid.

vrg3 · Post by **vrg3** » Tue Apr 19, 2005 3:33 am

Elevation thingie?

http://www.graphics.cornell.edu/~v/vacuum/

You're talking about hose J, right? You can either leave it or remove it and cap the stuff off. It doesn't really matter.

You should cap off the now-unused fittings on the solenoid though. One 3/16" cap and one 1/4" cap should fit neatly.

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DIY MBC boost controller

DIY MBC boost controller