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Salutations:
Much appreciated info and detail - thank you. Hope you don't mind dumb conversation on this (I've got a ton of questions). I'm running Trionic 1993 Aero with fly-by-wire (motorized) TCS (switched) throttle body - which you seem to be saying isn't a good application for MBC+A(?).
I'm not so sure because while you are using it to better hold boost without bleed - my interest would be to use the regulator to stage boost over the range while protecting from overshoot. I'm probably missing something, but can't the regulator allow you to better adjust the rate at which pressure is applied to the wastegate over a given boost run as well?
Personally - I think that the basic spring and ball is a pretty dodgy way to control boost. The spring ages, assuming you don't bind it up on a hard push along the way and even then, the ball and seat corrode and collect grits pretty quickly. But mostly - unless you have some serious access to some sort of mini-progressives - the internal spring is going to control the wastegate harshly. And that is fatal to the 9000 on a lot of really expensive levels.
The (now only) appeal of the 9000 Turbo factory BPC in everyday use is not the testicle return when the turbo snaps on strong - but more the smooth escalation of truly remarkable power as the Turbo comes progressively on.
As Mr Yankton proved, the 9000 can be made into a serious race monster (again cudo's) - but it just isn't likely toss around like either generation 900 with equal treatments (as I hope Mr Yankton will shortly prove with his very exciting new project). That said, I sold out a perfectly sound NG900 to buy our 1993 9000 Aero for the above noted testicle return when needed. It's a family hotrod, if that makes any sense.
Anyway - if you read my link, you will have noted that I ended up reversing the internal BPC solenoid so that the control disk is now providing limitless boost instead of base boost - but it is metering it out using the OEM air circuits so it doesn't snap power on or off anywhere in the range. However, it also stands a good chance of blowing out the engine as it no longer opens the waste gate - ever. At least that is what I am guessing.
Normally, as installed, the internal control disk is drawn to the upper coil by basic magnetism if the lower coil fails - it defaults to base boost by locking off the air channel. This is why there is no difference in boost when you pull the loom connector off on a bad BPC unit.
Currently - it is still delivering boost progressively through the range and now somewhat earlier because I have removed the wire covering about 1/3 of the rear facing vent inside the BPC collar. However - the only protection for over boost is a good needle based Audi BOV which I think is set to release a little earlier. It starts to release some pressure in the slotted red/yellow zone - but eventually reaches it's max flow well before the turbo is finished added more pressure of course.
So, given I want to remove the BPC from the circuit (it's damaged enough that I worry about it throwing metal or plastic into the lines) - I was hoping that I could use the MBC+A to provide some of the features of the OEM BPC - but in a more reliable mechanical fashion than a simple MBC.
I'm now sort of worried that I'm on the wrong trail. What are your thoughts?
Dexter J
posted by 24.222....
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