manual boost controller question????
 

ok i bought this manual boost controller from ebay
http://cgi.ebay.com/ebaymotors/ws/eB...m=280119453721
i cant figure out how to install it. so i installed the t into the line from turbo to actuator. the off the third nipple i have a line running to the controller unit. as i open it it raises the boost but there is an open nipple. it just doesnt seem correct. please help me out. also as i take the control unit and try to blow threw one end i can easily blow threw it with it set at max boost when the boost is set at lowest boost i cant blow threw it at all.
my boost is turned up to 8-9 but only peaks there then drops to like 7 would that be normal ore is it maybe the boost controller?

let me draw a diagram...sit tight.

https://www.miataturbo.net/braineack/random/mbc.jpg


its a bleed type MBC....the small sqaure is just a tee...and the large valve is just a needle valve...

ummm well thats what i was thinking but she is running 9 lbs of boost and noot so jumpy now that i put it inline. i dont know. its only gotta last for a bit im gunna get an electronic 2 stage boost controller soon.

Whats the grey portion of the diagram represent?

the port on the intake manifold, throttle body to be more precise.

Actually the grey part is the MBC bleeding off pressure, so Grey=Air Flow.
The boost source is coming from the compressor itself instead of the intake or throttlebody.

wtf, that setup is too complicated.... If it were me I would just stick the mbc between the boost source and the actuator.

I stand corrected.

I think the T has the restrictor pill in it as well. The feed from the turbo outlet can supply more cfm then you can vent which is why a restrictor is used. For example. 1/16" pill with 1/16" bleed drops pressure to the wastegate 50% (about) and it takes 20lbs of boost at the pill to make 10 at the wastegate if your bleading off 50%. I hope I made that make sence. If you know electronics it works like a resistor divider.

Brain loves ms paint ?

too much anti aliasing for it to be paint.

Yeah thats a little weird compared to what I'm used to.
Long as it works though.

that was adobe illustrator....(using laptop with no mouse :( )

its a basic bleed type MBC....the tee restricts the airflow and probably is a one was check valve on the blue port (that way it doesn't cause vacuum leak at idle) then when boost enters the wastegate so of the air gets bleed out of the line before it reaches the wastegate so the boost goes higher.

http://www.gusmahon.org/images/turbobleed.jpeg

the other end of the contorller its self (orange) can be left open like that with no vacum on it?

hence the check valve. losing the slightest bit of vacuum in that location under boost will do nothing to your A/F mixture. The check valve prevents it from leaking at idle.

Um....Sorry If im dumb. But, so your saying with the one way check valve you can leave the other end open?

boost can leave, vacuum won't get pulled in.

Braineack, So is that a yes? You can leave it open? I dont understand the "boost can leave" part. Sorry for being difficult.
Thanks :D

yeah, there's nothing wrong with it...it's how the BEGi FMU works as well.

Ok cool thanks. Thanks for not being harsh : / lol

what would be bad is the vacuum leak at idle.

But I mean....it would be at idle. I dont see what would be wrong, as long as it doesnt leak when you throttle it...Right? Or would it give a lag

the whole point is to reduce the amount of boost into the wastegate.

say the wastegate opens at 7psi. a way to control that is to reduce the amount of boost the wastegate sees. If you bleed the boost to just the wategate it won't open at 7psi because you've reduced the amount of boost in just that small section of vacuum line. When you adjust the amount of leak, you control the level of boost.

the check valve ensures that when you are idling or cruising you do not have a vacuum leak, as that will screw up your AFR. In boost, the very small amount of boost you are bleeding off does little/nothing.

Ohh Ok. I somewhat understand that. Thanks again. :D

typically people now use the ball-and-spring MBC:

http://www.rev2red.com/images/cars/faq/mbcdiagram.jpg

the idea here is keeping the wastegate closed as long as possible to increase spool, all while being able to maintain control of your boost level.

the way it works is completely sealing the boost from entering the wastegate. keeping the wastegate shut helps increase your spool-up rate. the bleed-type MBC always allows some boost to slightly open the wastegate more and more adversly affect spool.

you set your boost level by the pre-load on the spring inside the MBC. once the boost overcomes that pre-load then ball lifts out of the way and boost will enter the wastegate and it will open the flapper.

The piece in the last post looks easy enough to make from various Home Despot parts.

I assume the in comes from the turbo and the out goes to the wastegate?

What sort of spring do you end up using? Is there a measure for tension that it holds? Am I thinking about this too much?

My bad, found this by searching some more.

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