Gm Boost Control Solenoid

It's the part sitting in my car currently doing nothing causing me to be boost challenged :crybaby2:

It controls boost by blocking the pressure from the turbo outlet to the wastegate opposed to bleeding it out to the intake like the stock one. Since it's directly blocking pressure and isn't reliant on restrictors and t fittings it provides quicker response, a wider level of adjustment, and the ability to hold more boost and longer. Ralli has one successfully installed and I went for a ride last night (after giving up on mine for the evening) and it really is a nice upgrade.

 
It's the part sitting in my car currently doing nothing causing me to be boost challenged :crybaby2:

It controls boost by blocking the pressure from the turbo outlet to the wastegate opposed to bleeding it out to the intake like the stock one. Since it's directly blocking pressure and isn't reliant on restrictors and t fittings it provides quicker response, a wider level of adjustment, and the ability to hold more boost and longer. Ralli has one successfully installed and I went for a ride last night (after giving up on mine for the evening) and it really is a nice upgrade.
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It is a quite impressive upgrade, especially for the 2.0, but should make a difference on all tubro Subarus using a bleed type solenoid (all of the ones I know of). Its essentially the same thing as the Perrin BCS or the prodrive one, only cheaper. It was actually used on the old Typhoon I believe. It does require extensive tuning however.

If it was something you were interested I can help you out. I do know that XPT tuning as some OTS maps for purchase for with GM BCS, but not sure if there are any for the STI.

Yeah, we are problem solving Gabe's right now, it doesn't appear to be functioning... it was installed exactly the same as mine...

 
Im getting a custom tune very shortly so im trying to throw everything on at once that might help before I go. Yea I am running xpt but they dont have anything at the moment for the sti and a bcs.

 
If you decide to install before the tune just hook the wastegate up to the turbo outlet, and then hook it up properly for the tune to avoid boost issues. People have hooked it up on the stock STi running the stock map without issues, but better safe than sorry. Don't run it on a more aggressive map that is not setup up for it though.

We'll get it all figured out Sat. Troubleshooting sipping beers and eating BBQ seems like a lot more fun than troubleshooting in the cold and dark starving for dinner :thumbsup:.

 
honestly as i told ya nate its a waste of time... I had one on my car and decided I got way better boost response with a turbo xs hp mbc... dont get it, i wont help you work on your car. :pottytrain2:

 
honestly as i told ya nate its a waste of time... I had one on my car and decided I got way better boost response with a turbo xs hp mbc... dont get it, i wont help you work on your car. :pottytrain2:
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IMO (nothing against yours pat) I feel more comfortable using the factory ECU boost controls, and I just personally dont like using a MBC on something that has electronic boost control from the factory.

But, at the same time, Pat, I do believe you had a UTEC for tuning to go with that, am I correct?

Essentially the GM BCS is basically a better working 'factory piece' (obviously requires tuning), the MBC is seperate from that.

And to Pat's defense, there have been people that have succesfully tuned for a MBC and had great gains overall and in response.

I've found that with mine on my 2.0 that I've been able to build a ton more boost, and been able to hold much more boost longer. I've actually maxed out the stock injectors and have had to turn down the boost while I wait for the used 06/07 injectors (they are 565cc (ish) vs the 2.0's 420cc). Once I get those and tune for them I'll be able to turn the boost back up for the top and and not run out of injectors.

 
So we figured out the issue this weekend :headbang:. It wasn't that the GMBCS wasn't working it was that my stock bleed system was barely working. For whatever reason the wastegate actuator was never seeing much boost pressure. After tightening the wastegate arm a couple of turns and actually upping the WGDCs over stock boost was right on target. And like was said boost builds quicker, they system is more responsive, and it looks like I will be able to hold more boost to redline. Nice improvement over stock and a good add on for anyone looking to use the stock boost control system.

This does help explain some of the quirks I ran into trying to tune boost using the stock system and my issues with the car surging and continuing to build boost after I let off the gas.

 
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