DIY MBC works?

[DJYoshaBYD]

I just built a DIY MBC... I followed the instructions exactly and even put a bleeder hole where it told me to... but the MBC would not work right... finally I decided to tape the hole, and now it works fine.. holds at 10 psi and doesnt move... Why do MBCs have bleeder holes?

 

[turbosax2]

What psi were you running before you started using the mbc? Can you adjust the boost higher now?

 

[DJYoshaBYD]

yes... I had my stock BCS holding it at 7 psi... it wouldnt go any higher, and I know that is not stock boost... then I put in the MBC I made, set it almost to the lowest setting and it held SUPER solid at 10 psi... turned it up a bit and got 12, but I cant run it like that because I have no supporting mods... fuel pump rewire is next.....

I just dont understand why an MBC would need a bleeder hole

 

[turbosax2]

Then the boost signal rushes past the ball on its way to the Wastegate Actuator. The reason for that hole is to allow the "column" of charged air, or "boost signal", to drain or "bleed" out of the hose that sent the signal to the Wastegate Actuator. Without that hole, the charged air in the hose to the Wastegate Actuator would tend to "get trapped" and would slow the proper closing of the Wastegate. Technically, it is an inefficiency to allow some boost to escape, but it is a very small inefficiency that has a good trade-off. The inefficiency is relatively small so it really is not even worth mentioning... but that hole is a source of curiosity to many, so an explanation was warranted. Some ball-and-spring type controllers may not have such a hole and in those cases, the manufacturer may advise a small diameter "T" fitting or some other means of providing release hole.

http://dsmtuners.com/forums/showthread.php?t=113032&highlight=bleeder+hole

 

[DJYoshaBYD]

when the hole is open, it does not control right... When it is taped shut, it controls how it should.... man this is weird

 

[turbosax2]

Do you have the mbc on the bov line or between the compressor outlet and the wastegate?

 

[DJYoshaBYD]

compressor and wastegate... the right way

 

[turbosax2]

Sorry I can't help more - the only think I can think of is taking it apart again and just trying to make sure the bearings are fully sealing the holes at idle. Good luck

 

[xioca]

What size hole did you make? I'm asking this because the smallest drill bit i could ever find was one size to large. I ended up having to get a extreamly small bit for a dremel to do the job.

 

[DSMunknown]

Just a side comment - I started to build my own MBC, but finding all the right parts (including the ball and spring, which I think are the hardest to locate), driving here and there, not being sure if they would all work together just got me frustrated.

In the end, spending 38 bucks (shipped) for a proven MBC made me happy.

 

[xioca]

Just a side comment - I started to build my own MBC, but finding all the right parts (including the ball and spring, which I think are the hardest to locate), driving here and there, not being sure if they would all work together just got me frustrated.

In the end, spending 38 bucks (shipped) for a proven MBC made me happy.

If you have a small hardware store they often tend to carry the oddball springs and ball bearings. Lowes or homedepot has all the rest.

The hardest part for me was tapping for the knob.

 

[boostd92]

if you go to home depot, they sell this little valve, i will try to get a picture of 1, that is complete and ready to go on your car that can be used a a MBC. and its like $5

 

[xioca]

if you go to home depot, they sell this little valve, i will try to get a picture of 1, that is complete and ready to go on your car that can be used a a MBC. and its like $5

are you talking about a bleeder style mbc?

 

[boostd92]

thats exactly what im talking about, i used one for a long time and it worked great, i have an electronic now only because it came in the car, but i am actually thinking about unhooking that and taking a trip to home depot, the electronic is a pain in the ass

 

[luvmygst]

if you go to home depot, they sell this little valve, i will try to get a picture of 1, that is complete and ready to go on your car that can be used a a MBC. and its like $5

I would like to see that. I run hame made boost controllers on both my cars. I have even made 5or 6 for friends, they all work perfect. But if they have a valve that will work it would make it easier.

 

[kenamond]

The bleeder is crucial to the entire functioning of the MBC. As simple as this device looks and is constructed, it's operation is not nearly as easy to understand.

There's a 5-page thread on this:

http://www.dsmtuners.com/forums/showthread.php?t=236500

If you actually read all of that, good for you. If you still disagree with what Don and I are saying, I'd be happy to start another 5-pager. I've got an analogy that I'm dying to use!

 

[DJYoshaBYD]

well... I couldnt find the right size bit either, so I drilled until it just bbbaaarrrreeeellllyyy started break through.... I know I need one of these holes... but my MBC works just fine without one... sooo, I dont know..

BOOSTED92>>>> I want to see that home depot valve MBC that you are talking about... I wouldnt mind buying one of those as well...