I was thinking today...

The MBC might be able to be used as an adjustable "restrictor pill" on the turbo outlet side, before it goes to the T.

Do you think it's possible to use an MBC in this way instead of messing with different pill sizes?

 

I guess it would sorta work in theory but then again why bother? Just remove the pills and the BCS and just run with a MBC.

 

I've had better results holding boost with the BCS than with my Hallman

 

I've thought about doing this myself. Mostly to be able to go to race gas boost without reflashing. Let us know if you try it. I no longer have an MBC and dont want to buy one just for this purpose. I'm considering putting back on my Tru boost although the car seems to make less power at the same boost levels (spike), I really need to do some back to back logging though.

 

I will be running a MBC on top of the GM 3 port. I have heard from my tuner that this will act, as you said, a basically adjustable pill. It is a lot smoother since the MBC is faster then the BCS. This is how he runs it on his suby and it works great. Plus at about $40 for a used MBC, it isnt expensive either.

 

Just use an MBC. The holding boost thing makes next to no difference. Just because you run your turbo harder trying to hold 21psi at redline doesn't mean its helping to make more power.

 

Well the turbo will taper by redline for sure, no matter what you're using to control boost. But there's a big difference in mid-range power that's to be had with boost control adjustments.

I saw a massive increase in mid-range power when tuning the stock solenoid over my Hallman, both with 24psi spikes and 18psi at redline. The difference is definitely noticeable and the logs show it as well.

 

I'm using the BCS with #65 pill so I understand the RPM based boost control. But in all honesty you can only get soo much out of pump gas. Most people set the BC so they get 21-23psi in the mid range.

There is no reason to install an MBC inline with BCS.

 

There are numerous advantages of the 3-port. And holding 21psi at redline, even on pump, is better than holding 19psi or so with a MBC

I see no real issue with this, I'd rather just properly tune different maps with a 3-port unit however

 

If you're running a MBC without a tune, won't you run lean at the top of the power band? My guess is that the ECU expects a drop in boost pressure, and the stock fuel map is designed to deliver less fuel accordingly.

Can anyone validate/invalidate this?

 

The fuel map takes into effect how much load the engine is under (more boost = more load).

The ECU is smart enough to know that more load means more fuel, and it adjusts accordingly.

Either way, an MBC & pump gas on an otherwise stock Evo will definitely not make you run too lean. It could, however, put you into negative timing very easily

 

I used this setup on my VW, but it was a little different from the Evo. The MBC limits the flow to the solenoid just like a pre-solenoid bleeder or pill would.

 

A MBC in line with a BCS would not really be adjustable without readjusting the BDEL tables. You can adjust the MBC for less/more restriction but then your BDEL+Error correction would just bring it up/down, defeating the purpose.

 

I've seen 20whp differences from MBC to BCS. I would say that is a difference.

 

^^ You are lucky and I agree that one or the other may be better but running both is sort of .... well trashy. Might as well buy an RPM based EBC.