Caveat: I'm sure I'm not the first to ever try this. Full credit for this idea goes to Shane@DB Performance; he is always a bad influence

Theory: more boost = more power

Stock turbos taper. Aftermarket turbos taper. How do you try and cut down taper? A BCS seems to do the trick! However, they can be a tish inconsistent, and boost onset is not always as smooth or as early as a MBC. I tried the stock solenoids and they didn't work. So instead, I got a Pierburg 3-port BCS from CBRD (thanks chad! adapter fits PERFECT), ditched my stock solenoids, and mounted this on their little mount.



Here's JUST a MBC vs a MBC+Stock solenoid hybrid on my BBX. I tried both before the MBC and after it with pretty similar results. Maybe 1psi extra boost up top.



Now the 3-port. It is inline with the MBC, between the MBC outlet and the WGA, with the 3rd port 'venting' back to the intake. I'm only using 50% WGDC at 8000rpm so yea, there is some room to grow with this setup I think!


Note the kinda reverse taper, almost self-induced boost creep if you will. It will hold 28 flat or 26 flat or do this 26/27 going up to 28.5 thing pretty easily. This is like the perfect setup: the ease of adjustment of a MBC with the boost holding power of a BCS up top. Tunability is fantastic. I will have to report back on how consistent it is.

I just unplugged my secondary(passive) BCS and set all the tables to zero. No CEL yet.

Now, will it actually make more power? Stay tuned!

 

Been doing this with AEM cars and boost by speed, it works well. The thing is more boost out the top does not always equate more power. Its all relative to overall airflow from a given turbo.

 

God he is a bad influence

Interesting results though...perhaps this could help my massive drop from 37psi to 28psi at 9k.

 

can we have a schematic of vacumm/mbc/actuator piping etc

 

Aren't you already using a BCS? I'm guessing its already at 100% WGDC up there and if so there's not much a setup like this would do for you other than possibly maintain more consistent boost on your DD tune.

No schematic needed, it is simply inline with the MBC.

Turbo outlet pipe (boost) -> MBC -> BCS -> WGA. Just follow the directions for each and it is obvious (the 3port came with a diagram and every MBC on the planet is plumbed the same).

Good to know others are using this I know all too well that more boost up top does not necessarily mean more power, but it is certainly possible with the right parts combo. Even if it doesn't, this is (IMHO) a fantastic setup for those doing E85 or Alky kits with mapswitching; your low boost map simply would have 0% WGDC.

 

thanks for the feedback!!

cheers

cb

 

Thanks for the BCS recommendation! It works perfect! I want to get the most out of this little blue thing under the hood

 

pointless if you know how to tune 3 port solenoid boost control

 

^Yes because all the people talking about it in this thread can't tune a 3 port...sigh.

 

I desire logs of IAT, I found that when my GT35R wouldn't hold boost it was trying to tell me out of juice and the IAT would sky rocket when I tried to get it to hold the boost with my E-boost2
-James

 

Like I said, this will only work if your FMIC can keep up

 

I must be missing something?

But what the hell are you talking about?

At top end a 100% WGDC on a 3port will net you the most boost your turbo + setup can handle...

At spool if you tune the WGDC curve correctly you should again get the most boost your turbo + setup can handle..

 

I'm looking for three things: ease of dialing in base boost (mbc), consistency season to season (mbc--and if it doesn't, easy easy to bring it back inline), and no taper (BCS).

Yes, exactly! A MBC will taper a bit towards redline. Adding in some WGDC allows you to hold more boost to redline and thus more power. I'm only running 50% WGDC from 7000+ so this setup has more potential left on the table.


Huh? Didn't you write a mod in v7 to make wgdc hold 100% until certain load? The difference between a MBC and a normal BCS car is a BCS car will allow the wastegate to slightly crack open while the turbo develops full boost. Until it reaches the set value a MBC stays closed. If a bcs breaks past the wga pressure but not up to desired boost level, the bcs allows (example: 50% BWGDC @ 4000rpm?) 50% of the air to reach the wga and it will crack open slightly, slowing spool.

I can feel the difference driving a bcs car vs a mbc car. I'm basically looking for the best of both worlds!

On top of all that, you can use this for your base (pump gas) map on an alky setup and then use WGDC to set high boost on your alt maps.

Is this really tephra asking these questions? Are you just messing with me!? LOL.

 

yes and the wgdc hold was pretty useless mod once you started using gear based control.

even thou we dont have FULL gear control on the X - the crossover method is still pretty good...

if you run 100% WGDC during spool, set your cross over point right you should see the WG kept closed for most of the spool stage...

in summary - the MBC might offer a slightly better spool than BCS, but i would only think by a few rpm, nothing substantial..

 

I haven't tried the crossover method as I've ONLY ever used a MBC on my X. On my 8 though I had consistency problems from time to time. Whether it was because of the wild temperature swings where I live (-40°F to +100°F - Minnesota!) or because I was constantly dinking with the car (that is another issue entirely), I want a simple, solid setup and this will theoretically give me the best of both worlds