Type C and I made two different mbc's for my car,
the first one, (ball and spring) would either run of the wastegate spring, or boost whatever the turbo could boost.
the second, (bleed type) actually moved the boost up to .9 bar, but then it fell back down to .5 bar after hitting the peak, and then never would spike back up to .9bar in any gears afterwards. WTF !!!!
I can't just drive around at .5 bar boost, and i don't have the money for an ebc.
Could the waste gate arm be getting stuck after it opens? Has anone ever had this problem?
BTW, the turbo is a stock garret t-25 on an sr20det
Thanks-Billy

 

sounds like the ball and spring one was not adjustable enough...not sensitive enough i mean. how was it made?

 

2 little bits from home depot. various soft springs from true value, and a ball bearing from true value. It should work. I guess i can mess with it more, (diff springs)

 

with a threaded housing that can compress the spring, you should be able to adjust preload close enough. i havent done this myself so i guess it takes a bit of fiddling. i am probly going to break down and get a $15 grainger valve.

 

A stiffer spring solved my problem. I also made a tiny hole on the WG side of the MBC. It relieves the pressure when the ball is closed. The MBC acts as a check valve in the opposite direction. Fiddling is the only way to tune it, lots of fiddling....

 

WTF is a grainger valve?
I also had a bleeder with the ball and spring to actaully hold peak boost, if i didn't have it on there the boost would fall off.

 

Something like this...
http://www.grainger.com/Grainger/pro...mId=1611729925

 

so that is basically like the bleeder i have just a valva, what is so special to make that worth $15 instead of $.99??

 

Your bleeder + relief valve is actually the best you can do with MBC madness. The ball/spring would hold boost until a certain pressure is reached and the bleeder holds peak pressure. You had it all along, just need to tune the bleeder first then the ball/spring....
http://www.autospeed.com/A_0670/page1.html

For your reading pleasure....

 

i just dont get it...whats the point of that guy having a pressure relief valve AND a pressure regulator? you can set the boost pressure with just the relief valve, no?

 

I too was going to try the home made MBC for my turbo setup. but a pal of mine is using pressure switches for his (his are NOS switches to be exact). they are like $60.00 canadian, so like maybe 35 USD. Anyway je uses it with a stock honda selenoid a a vacume tester to set, real simple.

check it out




So basically its fool proof and accurate and safe. The waste gate see's no boost till the boost switch lets the selenoid see it.

I think all of that makes sense.

This is all with the internal waste gate on mitsu turbos, I think the stock springs are 5.5 or 6psi?

 

oh yeah there are two there, one for boost control and one for his alcohol injection for intake cooling pruposes.