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Kjott21 03-24-2009 06:05 PM

Aftermarket Boost Control Solenoids
Factory boost control relies on a flimsy, inefficient solenoid. When boost levels are increased over stock, the factory actuators fail to properly meter boost. The resulting spikes, dips and erratic response can damage your engine and spoil the performance gains. An upgraded electronic boost control solenoid allows a much lower waste gate duty cycle to produce higher boost levels giving tuners better control and decreasing spool time. Now lets discuss why.

Stock 2-Port Operation
The stock solenoid is part of the stock bleed-based boost control system. When the solenoid is off (closed), pressurized air from the compressor is fed straight into the wastegate control. Any increase in compressor pressure beyond the rated pressure of the wastegate control results in the wastegate being opened, preventing buildup of boost.
When energized (opened), air is allowed to bleed off the compressor-to-wastegate line by way of a “T” connector. This prevents the wastegate from seeing the full compressor pressure, allowing boost to build. Most model years include a restrictor pill in the hose connecting the compressor to the “T” which meters the air for the stock ECU calibration.
While the stock system operates adequately, it can lead to problems at higher-than-stock boost levels. Since the bleed system is sized for the stock turbo at stock boost levels, it is typically incapable of correctly metering air at higher boost, allowing the wastegate to see pressure and open before intended.
Additionally, since the wastegate is never completely cut off from seeing compressor pressure, it can open at low boost levels and inhibit boost buildup. Ideally, the wastegate should remain entirely closed for fastest boost buildup (as all exhaust is then forced through the turbine).

Aftermarket 3-Port Operation
A 3-port solenoid does away with the bleed-based system, explicitly shunting air from the compressor to the wastegate, or compressor to vent (or back into the intake post-MAF, OEM-style). Drawbacks of the bleed-based system are thus eliminated, with the wastegate seeing literally no pressure when the solenoid is energized, to seeing all of the compressor pressure when the solenoid is de-energized.
Now able to totally control the opening and closing of the wastegate, the ECU is able to control boost with greater precision and reduced response time.

This modification will make your current boost map OBSOLETE. You MUST retune boost. If you have no way to tune your boost control tables, you should NOT do this mod.

There are a lot of options out there. Some are a little easier to install than others, but all perform the same function. I have done some research in the solenoids available. If you do a little looking around you can find reviews for each of them:

GM 3 Port ~$65:
GM boost solenoid for Typhoon, GM Part # 1997152($48.89) Pigtails, GM Part # 12102747($15.40)
[url=]Full DIY: GM solenoid install (56k warning) - NASIOC[/url]
Alternately: ACDELCO solenoid part # 214474 and ACDELCO ABS modulator pigtale part # PT374

Prodrive BCS ~$125:

Perrin 3 Port ~$100:
[url=]Perrin Performance - Boost Control Solenoid[/url]

IxizConcept IxizEBCS ~$68:

Grainger 3 Port ~$30:
[url=]Pneumatics & Hydraulics > Valves > Solenoid Air Control Valves > Valve,Solenoid,1/8 In : Grainger Industrial Supply[/url]

Grainger 4 Port (for EWG) ~$57:
[url=]Pneumatics & Hydraulics > Valves > Solenoid Air Control Valves > Valve,Solenoid,1/8 In : Grainger Industrial Supply[/url]
[url=]NASIOC - View Single Post - Full DIY: GM solenoid install (56k warning)[/url]

GrimmSpeed 3 Port ~$110:

MAC 3 Port ~$26:
MAC valve part # 35A-AAA-DDBA-1BA

I took info from various sources including the installation instructions from GrimmSpeed and Perrin, and put it together for this article. I put it together because I couldn't find a good article that told why the boost control solenoid was a good modification.

[SIZE="4"][color=red]**** This guide is my made up of my own opinions and the knowledge that I have gained in the past 3 years of WRX ownership and modification. I take no responsibility for damages or legal issues from following this guide. The decision and responsibility to proceed is yours and yours alone.****[/color][/SIZE]

dumdum 03-25-2009 08:50 AM

Nice write up!Maybe they will make it a sticky so none of the ADHD kids will read itROFL:DAlso this has some info on using 3 solenoids on EWG's and lots of pictures:
[url=]How Subaru’s Factory Boost Control System Works - COBB Forums[/url]

mosc 03-25-2009 09:07 AM


metroscub 03-27-2009 04:08 AM

Just to add, Next month Ixiz has a really top notch MANUAL EBCS coming out, so that may be a good option for everyone!

wrx9wagon 03-27-2009 11:27 AM

Nice write up +1

pimmeh 09-14-2011 12:37 PM

One thing im not completely clear on...
im buying a 3port and i'm running the AP V2. It seem that some people are saying the AP will recognize the 3port but does that mean i need to re-flash with it on? or have someone completely redo my maps?

i guess what i'm saying is exactly what is required to run a 3 port bcs when using the AP as far as maps are required!? it doesnt seem that there are any CObb maps on the site for use with a 3port?

pzr2874 09-14-2011 02:15 PM

No, no OTS maps are available.... you need a specific tune for YOUR car.

turmic 09-14-2011 05:55 PM

What paul seek out a professional tuner to have them make a custom map for your 3 port bcs.

Btw, which 3 port are you using?

pimmeh 09-14-2011 06:14 PM

i havent purchased it yet. i was going to do it today but i'd like to have a conversation with my local tuner shop and make sure they're good with AP custom mapping first. other wise i'll put it off for a bit. the car is running great, if the load changes the boost can be a little fluttery but other than that its good. the grimmspeed 3 port is likely the one i'll go with. i'm pretty happy with the power the car makes right now so i'm looking to do some good support mods just to ensure she's healthy! ie 3 port, fuel pump, maybe an intercooler. then next summer drop a 16g and some pinks in..

turmic 09-14-2011 06:33 PM

I use the Grimmspeed 3 port and the only other one I'd suggest is a prodrive 3 port. Unless you can get your hands on a GM 3 port.

Check here: [url=] - Dealers [Country][/url] and see if they are certified.

psinuse 09-14-2011 08:36 PM

I have been using the GMBCS for 2 years now and honestly I would go with Grimmspeed. The ones I have tuned were much easier to dial in than the GM one.

turmic 09-14-2011 09:31 PM

Nice to know Keith

psinuse 09-15-2011 05:14 AM

Well I know of a few tuners that would rather use the Grimmspeed one and they will say the same thing. Ask your guy Kirt and see what he says?

turmic 09-15-2011 10:06 PM

My tuner won't touch it...I know some guys say its great. My tuner prefers Prodrive's 3 port bcs and Grimmspeed's 3 port bcs.

psinuse 09-17-2011 04:02 PM

Wonder if we should throw in the GMBCS/MBC hybrid boost control. I have been thinking about this, but haven't found much on it. Anyone here doing this, likes, dislikes and tuning issues?

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