[Muffnbluff]

UPDATE:
Thanks to 06SpecC for finding this video, it's very informative.

YouTube - Wastegates - GCG Turbo's


What is a wastegate?

A wastegate is a valve that diverts exhaust gases away from the turbine wheel in a turbocharged engine system. Diversion of exhaust gases causes the turbine to lose speed, which in turn reduces the rotating speed of the compressor. The primary function of the wastegate is to stabilize boost pressure in turbocharger systems, to protect the engine and the turbocharger. The wastegate is controlled by a wastegate actuator in which the actuator is controlled by pressure coming from the intake manifold.

What is an external wastegate?

An external wastegate is a separate self-contained mechanism used to divert exhaust gas before it can enter the turbo. An external wastegate requires a specially constructed up-pipe with a dedicated runner going to the wastegate. External wastegates are commonly used for regulating boost levels more precisely than internal wastegates in high power applications.





Why is an EWG better than an IWG?

External wastegates can be much larger since there is no constraint of integrating the valve or spring into the turbocharger and turbine housing. Therefore an external wastegate can more accurately control the amount of exhaust that enters the turbo, hence controlling boost pressure more effectively.

What does an EWG sound like?

The clip in the following thread from IWSTI member TurboQueef provides an excellent example of the sound of a 38mm Tial EWG dumping to atmosphere.
HD & SD video of an Ultimate Racing Gated Up-Pipe

Oh $#!& that clip sounded pretty loud! Is there a way to make it quieter?

Yes, the dump tube from the EWG can be routed back into the exhaust system, eliminating much of the noise. However, the consensus among many people is that this will cause you to lose some power due to the turbulence and increased backpressure of the gas from the EWG running into the gas coming from the turbo.

What are the benefits of an EWG?

First and foremost the purpose of an EWG is to control boost more accurately. Say goodbye to the days of your turbo creeping out of control in the winter.

However, in certain applications the addition of an EWG can help to "free up" power not only by controlling boost, but by reducing the exhaust pressure in the turbo. For an explanation of this, see Clark Turner's writeup on EWGs and tuning.

NASIOC - View Single Post - External wastegates and tuning.

*Disclaimer: You must be tuned for the EWG to reap the benefits. Any time you make a mechanical change to your setup that will affect the way boost is controlled you should have a tuner tune/retune your car. Also, if you decide to install the EWG yourself, make sure you reconnect all of the vacuum lines correctly. Not doing so could lead to overboosting or other problems which you don't want to have on the dyno. Not every turbo setup will see the same results as described in Clark's thread above.

Who makes EWG kits for my STi?

Ultimate Racing
TurboXS
P&L (Modified TurboXS)
Element Tuning

The most common brand of EWGs run is TiaL, as well as a few people running TurboSmart. The two most common sizes are 38mm and 44mm. One benefit to a 44mm setup is that the EWG uses V-band clamps that will guarantee no exhaust gas leakage. There are several reports of the paper gaskets that come with the Tial 38mm EWG blowing. However, many people have installed "Fire Ring" gaskets on 38mm EWGs without anny issues.

What do I need to do to run an EWG on my IWG turbo?

The IWG will have to be sealed shut. There are two options available:
1) Welding - you can weld the actual wastegate door shut or you can weld the wastegate arm to the turbo.
2) Bracket - you can use some type of bracket/bolt/clamp to hold the wastegate arm in place, for example this custom bracket from IWSTI member jasv11:


Discussion of Tial Wastegates and Springs

http://www.iwsti.com/forums/2979700-post484.html

[Muffnbluff]

This was in response to the frenzy of EWG questions lately. If anyone believes any info in here is inaccurate feel free to respond. If the consensus is I'm totally wrong on something, let me know and I'll update my post.

[Loubaru]

Thanks. Great post, I'm sure that will help a lot of people out.

[CenCali07STI]

Originally Posted by Muffnbluff

I know how they work but one thing I have always wondered is would it be better to mount the wastgate runner tube from the up-pipe pointing down. The reason I ask is because if the exhaust hits up against that wastegate valve it has to create backpressure hitting that valve head on whether its open or closed. Now maybe pointing it down wont release the air as easily and the valve might have to open even further to be able to bleed off enough exhaust since the exhaust pressure is not pushing right against the valve but I assume it would still work. What do you guys think?

[Turninconcepts.com]

Originally Posted by CenCali07STI

I know how they work but one thing I have always wondered is would it be better to mount the wastgate runner tube from the up-pipe pointing down. The reason I ask is because if the exhaust hits up against that wastegate valve it has to create backpressure hitting that valve head on whether its open or closed. Now maybe pointing it down wont release the air as easily and the valve might have to open even further to be able to bleed off enough exhaust since the exhaust pressure is not pushing right against the valve but I assume it would still work. What do you guys think?

If you point it down then the gases have to do a 180 to exit. Gas does not like to do an about face like that, and since the goal is to divert air from the turbine wheel via an alternate pathway you need to make it as smooth a transition as possible.

[Turninconcepts.com]

Originally Posted by Muffnbluff

This was in response to the frenzy of EWG questions lately. If anyone believes any info in here is inaccurate feel free to respond. If the consensus is I'm totally wrong on something, let me know and I'll update my post.

My hat is off to you, sir! You are absolutely correct that the info and discussions are getting much too scattered to be any good.

[CenCali07STI]

Originally Posted by Turninconcepts.com

If you point it down then the gases have to do a 180 to exit. Gas does not like to do an about face like that, and since the goal is to divert air from the turbine wheel via an alternate pathway you need to make it as smooth a transition as possible.

Gotcha just figured I would ask

[06SpecC]

Very nice job! Someone make this a sticky!

[Muffnbluff]

Originally Posted by CenCali07STI

Gotcha just figured I would ask

By all means, questions like that are the point of this thread. I hadn't even thought about that question before!

Originally Posted by 06SpecC

Very nice job! Someone make this a sticky!

If others want it to be a Sticky I'll go ahead and Sticky it. (I'm a mod now, yay. )

[13onesti]

nice thread..

Just by adding EWG doesnt mean you gonna gain power. tuning plays a big roll on power gains.
EWG is basicly a super advance boost controller. The only real benifits from it is VERY BADASS SOUND, and smoother flow on the exhaust.

VF39 with EWG --- FTMFW.....