does an MBC do the same thing as a wastegate? how is an MBC used in conjunction with a wastegate, or is it??

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>does an MBC do the same thing as a wastegate?

No.. not even remotely close.

>how is an MBC
>used in conjunction with a wastegate, or is it??

A wastegate gets a pessure signal from the turbo. The pressure signal pushes up on a diaphram, which is attached to a valve. The upward motion of the diaphrams works against a spring. The heavier the spring, the more boost pressure it takes to open the wastegate valve. When the wastegate valve opens, exhaust gas bypasses the turbine housing, which controls turbine speed and thusly boost pressure by controlling the compressor speed.

All an MBC does it add an extra spring between the turbo and wastegate, which the boost signal must force open. Once it forces open the MBC's spring, the pressure signal goes through to the wastegate, which opens and limits the compressor speed, and thus boost.

make any sense?

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actualy yes it does. (i think) So i can run the MBC on the line from the compressor to the wastegate and, for example, set the MBC to open at 6psi so that when it does it will let the siganl thru to the wastegate and allow it to open? is that it?
if thats correct, then what would the wastegate be set to in order for it to open once the signal got to it? if its 6psi also whats the need for the MBC?
sorry for all the questions..
tim

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basically a MBC limits the amount of boost pressure the wastegate acutaually sees. Lets say your wastegate acuator spring is set to open the wastegate at 8 psi. So when the boost pressure of 8 psi reaches the wastegate actuator, it opens the wastegate and bypasses some exaust gas to help the turbo not spool up any more boost pressure. Now if you put a boost controller on, since that lets you adjust how much pressure comes out of it(its really a pressure limiting valve), then you can run lets say 15 psi, because then only 8 psi is coming out the boost controller, but you have more pressure because you really have 15 psi on the turbo outlet. It really "fools" the wastegate actuator to think its running its spring presure setting. Hope this makes sense.

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Don't forget Tim. You will NEED to modify your wastegate actuator. Otherwise it will boost like 11 lbs and blow your shit up...the T25 spring is set for around 11 lbs...you need to fool it into thinking it is lower. Either that or buy an wastegate actuator that is set for 5 lbs. Or get an external WG. I think you can get them as low as 3 lbs. But a boost controler will not let you boost lower than the initial setting on the wastegate spring. Only higher.

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