i have done boost leak checks on my car and i have always had alot of air coming out of the valve cover (port that goes to the intake tube). i usually have to plug the line to get it to hold. when my cams were installed i had replaced my valvesprings so they pressurized each chamber and they all held great no leaks.


the BBK is great at holding that boost. im going to retune at 28 and im hoping it will have minimal taper as well if it can hold 25psi by redline i'll be stoked

 

When I mentioned MBC "set-up", I was not referring merely to the simplistic task of connecting the two vacuum hoses to the ports on the MBC body. I stated MBC set-up, not merely the hooking-up of two vacuum hoses. FYI, just as there is a right way and a wrong way to "set-up" an EBC, likewise there is a right way and a wrong way to set-up an MBC.

By setting up an MBC properly I was alluding to certain related adjustments that go beyond the simple process of connecting the hoses and the equally simple act of turning the adjustment knob. There is considerably more to it than that. Just because you hooked up the hoses and turned the knob, doesn't mean that you set it up properly. You sure won't get the best results doing it your way. Your analysis oversimplifies a problem(boost taper) which could, in fact, very well be caused by several factors other than and independent of the choice, installation and employment of any one particular type of boost control device.

Again, IMO, you may be steering the OP off course by suggesting with such certainty that his MBC is the cause of his turbo's boost taper issues. Agreed, under certain circumstances the MBC may sometimes be among the possible contributing factors in some boost taper scenarios. But, it is not, as you seem to be implying, the ONLY possible cause of boost taper issues under any and all circumstances.

Furthermore, I don't agree with your advice that simply installing an EBC, will a priori, cure his boost taper issue. The EBC is not by any means a universal cure-all for this type of boost taper issue. Ergo, the MBC is not the only possible, nor even the most likely root cause of his boost taper. I think that you are, at best, ill informed. But, of course, you are entitled to your own opinion.

Actually, I was not arguing about MBC's vs. EBC's. I don't champion MBC's at all. I just don't happen to agree with your generalizations that a MBC will always cause boost taper up top and that alternately, the EBC is a miracle cure for the MBC's supposed deficiencies. I am not really arguing. I simply choose to differ with you on this topic. I happen to be of the opinion that the OP's issues may not be related to his choice of boost control device at all.

Finally, EvoM is an open discussion forum. Divergent opinion is encouraged, as long as it does not lead off topic, or become disrespectful.

 

make sure to keep the oil cap off when boost leak testing so you dont pressurize the crankcase

 

Does your TD06 exhaust housing have a larger than stock wastegate flap?
If so, this could be the problem.
EBC will help, you can reduce the amount of boost that the wastegate actuator is seeing - closing the flapper which increases boost.

Cheers, Mike

 

Yes, the td06 does have larger than stock wastegate flapper.

I have atp gtx3076r now and so far boost can hold flat at 25 psi till redline on same boost controller.