EWG + EBCS Vacuum Plumbing Confusion - Subaru WRX Forum
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post #1 of 7 Old 09-21-2016, 01:02 PM Thread Starter
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Question EWG + EBCS Vacuum Plumbing Confusion

Hello all,

I'm putting on an EWG to help with boost spikes (and of course for other various reasons) but I'm perplexed by the plumbing recommendation from COBB (and probably others) on how to run the vacuum lines and how that works.

Here's the picture from COBB:


So in an IWG setup, port 1 goes to boost source (compressor outlet), port 3 is the bleed off back to intake and port 2 is the Wastegate.

When you add Wastegate duty cycles in the map, it effectively bleeds off some pressure back into the intake to prevent the WG arm from opening as much as it would without.

BUT

An EWG is reversed no? With the T in the diagram splitting off the boost source, the lower port (under the diaphragm) receives full boost all the time but the upper port only receives what's left after some pressure is bled off. That doesn't make sense to me, because wouldn't this make it run on spring pressure?

I can understand how the lower pressure area during boost that goes to the top port creates a sort of soft resistance to the spring but at the same time the lower port is getting even more pressure added and has the same spring force pushing right back.

Spring + boost < Negative spring + partial boost!?!? Maybe I'm just not visualizing the physics here. Maybe someone can chime in and fry my noodle.
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post #2 of 7 Old 09-22-2016, 05:42 AM
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skip the first part about IWG. at abut 1:50 he stats explaining the two ports on the EWG

you are essentially running a 4-port system.

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post #3 of 7 Old 09-22-2016, 05:44 AM
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ps: Brett is the leading engineer at Go Fast Bits (GFB) in case youre wondeirng of this dudes credibility.

im my opinoin, one of the top manufacturers or these products.

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post #4 of 7 Old 09-22-2016, 06:29 AM
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Well if you get a Tial that is not the correct set-up. This is another pic but if you go to Tial's Website an go here TiAL Sport - Wastegate Tech

This is pic is how I have mine set-up and approved by my tuner.
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post #5 of 7 Old 09-22-2016, 06:49 AM
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And the port 1 on the EBCS doesn't have to go back to the intake if you are running a SD based tune as told by my tuner. I have tried in run into the intake an vented an there is absolutely no difference. The port 1 is a pressure release so a only a MAF set-up needs it.

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post #6 of 7 Old 09-22-2016, 08:44 AM
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Quote:
Originally Posted by titter View Post
ps: Brett is the leading engineer at Go Fast Bits (GFB) in case youre wondeirng of this dudes credibility.

im my opinoin, one of the top manufacturers or these products.
Sorry, off topic, but MCM FTW! I love watching those guys and I really like their new Go Fast Brett segments.
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post #7 of 7 Old 09-26-2016, 12:03 PM Thread Starter
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Hey guys thanks for responding.

I watched the video and there's a lot of good info. However I already knew the stuff in it (I understand how EWG's work and how they're different from an internal). I also know there are other ways to plumb it up and those make sense to me. It's that particular way that has me perplexed.

I'm trying to understand the physics behind what actually happens in every chamber in the original setup and how the pressures work with one another to control the valve.

Thanks for all the input!
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