Please do. I wanted to do that myself but I don't have an air compressor to play with.

 

Hook up your vacuum cleaner hose to the exhaust port and get out some Jesus tape.

Theres quite a few uses for a vacuum cleaner other than just cleaning you know!

 

OK here is the deal. I played around this weekend with the hybrid setup using my new (to me) TurboXS BC-HPBC MBC. I used my shop compressor regulator to create various pressures between 7-20 psi and ran several tests using my turbo's wastegate (set to about 8-9 psi). The connection going to the bottom right is what I had the shop air connected to. The long and short of the test is this:

FTW - Hook up the connection on the vent side of the EBC to the incoming air, which is the opposite of how the NASIOC guy has it in his picture. This way it works. When the solenoid is off (no power, 0% DC) the wastegate responds normally. When the solenoid is on (powered, 100% DC) the MBC controls the wastegate and it takes more pressure to open.

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FTL - Hook up the connection on the vent side of the EBC to the outgoing air, which is how the NASIOC guy has it in his picture. This way it does not work. When the solenoid is off (no power, 0% DC) the wastegate responds normally. When the solenoid is on (powered, 100% DC) the wastegate will not open at all.


FIXED: Skidude try plugging the vent port (see below).

What seems to be going on in the FTL configuration is the EBC is venting too much air (at 100% DC) for pressure to build and open the wastegate. Even when I increased pressure it still would not open. Why this is not also the case in the FTW configuration is strange since the EBC is still venting air from the system. But whatever, on the bench top it works.

 

Even I can understand that!

ZX Tex

 

It gets better. So it occurred to me to try a third configuration, that is, with the vent plugged. And, it works, even in the FTL configuration.



Though I thought about plugging the vent before, I kept thinking the vent had to be left open because the system needs a way to bleed off the air in the wastegate diaphragm; this allows the wastegate to close when boost is released. But, then it occurred to me... When the EBC is in 0% DC, the wastegate acts just like it is connected directly to the manifold, and thus the pressure just vents back into the manifold like it normally would. No problem there. When the EBC is at 100%, the air is vented out through the bleed port in the MBC when boost is released, so no problem there either.

So the answer is, just plug the damn vent port and it should work!

And, blankity blank blank, wouldn't you know it, but I went back and read the NASIOC thread more carefully. It turns out the vent is plugged in his setup. You just cannot see it in the picture, and he only mentions it after someone asked about it. Easy to miss

EDIT: Attached is a corrected connection diagram.

 

makes sense it works in that configuration.

 

I must say I am quite disappointed in this thread.

Here I thought I had a new idea that nobody else was doing and then I'm directed here. It's funny, my emails to a few friends actually lay out the exact same reasons and benefits of the different setups and why it made sense to go this route. It almost looks like I plagiarized. That'll teach me to stop reading up on mt.net.

Anyway, I didn't have any concerns about the GM solenoid not working, I knew I could just cap off the vent from the beginning. Wasn't concerned about that boost pressure not being vented afterward and keeping the wastegate open since the ball&spring MBC I purchased had a small vent for this very same reason. What did concern me was the vent(on the MBC) being too large and bleeding off too much pressure when the solenoid was open for the wastegate to be pushed open. Well I set it all up today on the Machine(begi cold air box was in the way on the daily and I didnt feel like getting too into it). Turns out it's fine, the ~1/32" only made a small difference which I wanted anyway. Straight wastegate pressure went from 9 to about 10.5 which is perfect for me.

Here is how I am running it.

It's plumbed the same way as in the FTL pic above except the vent is capped.
The EBC is still connected to my MS with a toggle switch in line. Toggle switch off gives me wastegate pressure, about 10.5psi. On gives me MBC pressure, ~16psi. I am using the Boost duty target table to give me throttle sensitive boost control assistance. It's set up as follows:



This way in low traction conditions such as rain or snow I don't have to worry as much about the thing getting squirrly, I just flip off the switch. And by using the boost duty target table the transition from wastegate pressure to mbc pressure is much less abrupt. So now I have a boost controller that actually does what I expected the EBC function of MS to do. BRING ON THE VARYING AMBIENT TEMPS! I'm very happy with the setup. I already purchased for all 3 of our squirted turbo miatas, actually I did a group buy for 8 of them from NXS for a few friends. $14.75 each instead of $20. To me that beats visiting a few Home Depots and Lowes to source the parts $12/ea and then spending an hour or so making them.

 

See I couldn't run a MBC after I went with a 3" exhaust because I had such horrible boost creep. This is an interesting concept, in the least i could bleed the EBC to control the creep as well. I might give it a try.

 

My 3" dp/exhaust setup caused mad over boost till we ported the wastegate. I mean the thing would make 15 with the flapper door held open. I could make 6-7 revving in neutral.

 

I already ported mine, but I should have done more when it was off a few weeks ago. I still hit 10-11psi at redline on a 6psi wastegate.

 

Mine wasn't quite as bad as Paul's, but with the 3" Absurdflow and puny wastegate on the IHI turbo, I easily made 12-13 psi with no boost controller and an elongated actuator rod. Then I swapped the turbo for a BEGI ported version. Non-boost-controlled pressure dropped to 10-ish.

 

Realized there is no need for the 2nd T/Y if you route like this



Turns out a little cleaner.

 

I'm really sorry Paul, but .... you just posted the exact same diagram as the OP's "current" configuration in post #1.

 

If all you do is toggle it on and off, then whats the point of having the table have different DC%? Just make it all 100.

 

Because even when you do want full boost, you don't necessarily want it immediately upon pressing the gas pedal. That's the whole point of using an EBC at all -- variable boost based on throttle position. Having a middle row of 30 or 40 percent smoothes the power delivery.

Duh.

 

wait

isn't the single port on the GM solenoid the "common" port? ie should go to turbo?

 

Yes, it is. But in this configuration we're using it backward on purpose.

 

Typically I have the metal port to the boost source. That's the one thats alone on one side. But You can't use the solenoid as a switchable Y in that direction. Power off it flows through. Power on it's blocked, it doesn't flow to the vent side. Now if you swap the thing around and put the boost source to the port that typically would go to the wastegate it works perfectly. With power off it flows through to the metal port on the other side. With power on it closes the metal port and directs air out the vent port. Perfect.

At least that's the way it works in my house with as much pressure I can blow through the line.

 

I just looked at the OP's diagram and no I have it different and that's why mine works. He has the solenoid in the typical orientation which works fine if you just want to open and close a single path but does not work if you want a switchable path through the solenoid.

 

Paul, what's the MBC you buy?