EWG Questions

asc_up · Post by **asc_up** » Fri Nov 13, 2009 1:54 am

Ok, I've been reading information all over the internet about external wastegates for about 2.5 hours now and I still haven't found the answer I'm looking for.

I'm planning on buying an EWG + U.P. setup for my future setup (FP Green). I'd also like to use it with what I have right now, which is a VF39. The car is currently tuned for 17 PSI.

Would I be better off buying a 9 PSI spring for the EWG (which is what the WG duty cycle is tuned for on the Revtronix chip) OR is it possible for me to just buy a 17 PSI wastegate spring and run the EWG off of wastegate boost?

If I go with the latter of the two options, I should NOT have to worry about any sort of boost creep, correct?

Thanks for helping me understand all of this.

206er · Post by **206er** » Fri Nov 13, 2009 2:33 am

i'm kind of a noob with turbo stuff, but isn't boost creep more related to the size of the wastegate ie it's ability to bleed off exhaust pressure?
also if you run a 17lb spring you are stuck at 17 as your lowest pressure that you can run. no ability to turn it down without swapping out the spring.

asc_up · Post by **asc_up** » Fri Nov 13, 2009 10:51 am

Haha thanks for your reply. I think I just needed to take a break to think things through; it's pretty obvious to me that I need to stick with the 8-9 PSI spring.

NOW my question is, how do I hook up an EWG to our stock 3-port BCS?

Post by **Legacy777** » Fri Nov 13, 2009 7:21 pm

Quick question....Maybe I'm not getting the whole picture, but don't you need a turbo without an internal wastegate to run an external wastegate setup?

That or some method to keep the internal wastegate closed?

asc_up · Post by **asc_up** » Fri Nov 13, 2009 7:27 pm

Yes, you do. The FP Green has a welded IWG. My friend went this same route before he put a Green on his STi, so he has a IWG bracket (hold the WG shut) for a VF39 that I'll be taking off of his hands.

I think this is how the vacuum hoses need to be setup with our stock BCS. Can someone confirm this?

Post by **Legacy777** » Fri Nov 13, 2009 7:35 pm

Do you have a diagram of how the internal diaphragm is setup on the EWG?

asc_up · Post by **asc_up** » Fri Nov 13, 2009 7:39 pm

I don't, but here's the site for it: Click Me

Post by **Legacy777** » Fri Nov 13, 2009 7:51 pm

Based on Tial's drawing & Vikash's drawing,

http://www.tialmedia.com/documents/w3_t ... nstall.pdf
www.surrealmirage.com/vrg3/vacuum/ej22t_vacuum.png

I believe the diagram you posted above to be correct.

You would leave L & M (referenced from Vikash's drawing) where they are supposed to be connected to the turbo & boost control solenoid, and then connect K to the top side of the EWG, and leave J connected to the intake resonator, or pre-turbo piping.

Then the only thing you need to do is tee into M or L, and run a line to the bottom side of the EWG.

Clear as mud?

asc_up · Post by **asc_up** » Fri Nov 13, 2009 8:04 pm

Heh, just about.

Now I'm starting to think that I might have to hook up the BCS to the side port of the EWG if I want it to work 'right out of the box." This is because when the BCS is hooked up to the top, it is supposed to CUT the airflow when maximum boost is reached, that way the pressure from the side port can force the WG open.

Although, on our cars, the BCS is supposed to ALLOW all of the air to go straight to the WG so it can open.

Does that make sense?

Therefore, if I hook it up to the side, the BCS will act just as it does with the IWG. It holds back boost until maximum PSI is reached, and then injects it in through the side port, effectively opening the wastegate.

Basically, the top port is made to help keep the WG closed and the side is to open it. The DC of the stock BCS would need to be totally remapped for it work on the top port.

Oy, so much to think about. Haha.

Post by **Legacy777** » Fri Nov 13, 2009 8:31 pm

I think you're right.....I believe I had the "default" or non-energized ports mixed up.

Doing what you described above should work with the factory BCS and boost control mapping. It may not be ideal, but should work.

I'm going to check the spare BCS I have laying around at home to make sure I'm thinking correctly

asc_up · Post by **asc_up** » Fri Nov 13, 2009 8:50 pm

Awesome, thanks for doing that Josh.

Now I just had a thought. When referring to the diagram above, would the stock BCS work IF I switched the hoses on the solenoid that go to the intake and top of the WG?

That way, it would think it was bleeding off boost into the intake BUT in reality it would actually be helping to hold the WG shut as it should be. Then when the desired boost level was reached, it would click over and think it was supplying pressure to the factory WG, but it would be relieving pressure on the top port, thus allowing the boost from the side port to open the WG.

93forestpearl · Post by **93forestpearl** » Sat Nov 14, 2009 4:19 am

You typically run a spring that is half or more the pressure of your target boost. It all depends on how hard your wastegate has to work to bleed off sufficient exhaust pressure. A larger wastegate could get by with a lighter spring.

I prefer the "interrupt" method of plumbing, but that type of routing will leave in a fail bad mode. A bleed type will fail safe, but, depending on your boost control, can spool slightly slower in certain conditions.

asc_up · Post by **asc_up** » Sat Nov 14, 2009 4:46 am

Thanks for the info Dan. I went with the .6 bar spring which is just a little more than half of the boost I'll be running. How would you recommend running the stock BCS with the EWG (if at all)?

93forestpearl · Post by **93forestpearl** » Sat Nov 14, 2009 5:22 am

What are you controlling the stock solenoid with?

With the MAC 3-way solenoid valve I could configure it in a ton of routing options. I'm not sure what the stock solenoid is like, so its hard to say.

I will say that using the interrupt style made my turbo come on sooner, but that could have been partly due to my open loop boost control from my setup.

asc_up · Post by **asc_up** » Sat Nov 14, 2009 5:35 am

I'm using the stock ECU with the Revtronix Chip set at 17 PSI to control everything.

asc_up · Post by **asc_up** » Sat Nov 14, 2009 6:06 am

Ok guys, I have it about 98% figured out now.

Here is the stock boost control solenoid vacuum hose configuration:

Use the letters to refer to the diagram below.

I think it will work if I have it setup this way:

I will keep the existing pressure source to BCS line in place. The BCS to WG line will go to the bottom port of the EWG. I will then cap off the intake nipple on my coffee cup mod and route that hose to the top port on the EWG.

This way, while the BCS is trying to bleed boost away from the WG, it will be supplying pressure to the top port (instead of the intake), effectively helping to keep the WG shut. Then when max. PSI is reached, the BCS will function just as it normally would and close the intake/top port and supply pressure to the bottom port, which would open the WG.

Sound like it'll work? Anyone see any problems with this?

93forestpearl · Post by **93forestpearl** » Sat Nov 14, 2009 7:28 am

So where does the excess pressure go? The outlet of the BCS will reach the inlet pressure after a given time depending on duty cycle. No matter the duty cycle, the system will equalize at some point and your wastegate will be shut.

The stock configuration lets the pressure go a vacuum source, and isn't a closed system like the last diagram you posted, which doesn't make any sense.

93forestpearl · Post by **93forestpearl** » Sat Nov 14, 2009 7:32 am

Basically, you either run boost to the bottom port and bleed that, or run boost in parallel to both ports and bleed the top side.

asc_up · Post by **asc_up** » Sat Nov 14, 2009 8:07 am

Ah shoot! Good point, Dan! Thanks for catching that. So maybe what I'll do is run line K to the bottom port of the EWG and leave lines L/M and J in their stock configuration and just leave the top port of the EWG VTA.

Do you think there would be any problem with leaving the top port VTA?

asc_up · Post by **asc_up** » Sat Nov 14, 2009 10:43 am

Ok Josh, Dan and anyone else who can help, what if I had it configured like so....

If my logic is correct (which so far it hasn't been

), this configuration would sort of 'trick' the ECU into thinking it was doing its job. When the turbo is building boost, the ECU tells the BCS to bleed boost to the intake, but in reality it would actually be providing pressure to the top port. Then when the ECU realized that full boost had been achieved, it would tell the BCS to pressurize the line going to the IWG, but this line would actually be going to the intake, thus alleviating the pressure at the top port and allowing the EWG to open up.

This could definitely work as long as the ECU sets the BCS to 100% DC when full boost is reached. Now what would happen if the DC was at, say 80%? Would that still allow enough pressure to reach the top port and hold the EWG closed?

93forestpearl · Post by **93forestpearl** » Sat Nov 14, 2009 7:07 pm

That is how I ran mine. IIRC, I was up to about 55% duty cycle to reach 23 psi on my setup, but there are a lot of variables. The turbo, size of the wastegate, how the wastegate is plumbed, vented to atmosphere or routed back in, are all factors in how hard the system has to work to keep the turbo under control.

In that setup, pressure is fed to the top and bottom of the wastegate diaphram until the solenoid bleeds off the top side allowing the wastegate to open.

asc_up · Post by **asc_up** » Sat Nov 14, 2009 7:48 pm

Interesting. So even though the BCS wasn't at 100% duty cycle, it still alleviated enough pressure on the top port to allow the WG to open?

Do you see any problems with just running the IWG line to the bottom of the EWG and leaving the top port vented? From what I've read, that would work, but it won't give me as accurate control over boost.

93forestpearl · Post by **93forestpearl** » Sun Nov 15, 2009 2:26 am

Well, if you vent 100% of the pressure to the top port, you end up with boost pressure equal to your wastegate spring.

I ran both styles, and both were plenty accurate at holding a desired boost level. The interrupt method kept the wastegate closed at spoolup better, so I got more torqueout out of it. My stock STi clutch didn't slip until I used that method.

asc_up · Post by **asc_up** » Sun Nov 15, 2009 3:26 am

Forgive me, but what style is the "interrupt" style?

Judging by the name, I would assume it's: Compressor nipple ---> MBC ---> Bottom Port of EWG

If that's it, then I should be able to just use the stock solenoid in the stock vacuum line configuration, like this:

So, just to clarify, you HAVE run an EWG without the top port connected to anything and it controls boost perfectly?

93forestpearl · Post by **93forestpearl** » Sun Nov 15, 2009 5:32 pm

The "interrupt" method is the previous arrangement, where you bleen odd the top port. The "bleed" method is like your above post, bleeding the pressure off of the bottom only.

Both methods were plenty accurate. The interrupt style keptt he wastegate closed at spoolup better, but both had the same effectiveness at target boost.

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