External Wastegate After the Turbine??

[kylush]

Ok I'm a little confused. My turbo is making alot more noise then usual and I have a feeling it might be going bad so I was just looking around at new turbos. If i did get a new one it probably wouldn't be internally gated and would probably be running an open dump. Now most of the external wastegate setups that I've seen have the wastegate mounted to the manifold with an open or recirced dump tube coming off of it.

I was looking around for Dp's, downpipes, and dumptubes made up for this kind of setup but was having a hard time finding them for open dump setups so I'm assuming most of them are custom fabbed although i did find this....

EXTREME PSI : Your #1 Source for In Stock Performance Parts - Punishment Racing M/S 38mm Ext. Atmosphere O2 Housing: Mitsubishi Eclipse 90-99

Now..... how does this work?? Here is what i'm thinking... It's meant to be used with a manifold without wastegate provision and a turbo without an internal gate, and then the gate just mounts right after the turbine and the open dumptube mounts right to it?? Not sure how this works, I suppose if the pressure changes on the backside of the turbine wheel it can slow it and control it too right??

Anyone know anything about this or have any experience with a setup like this??
How do they compare to having the wastegate mounted to the manifold?? That is assuming my assumtions are right.

 

[turboking15]

that style uses an internally gated turbine housing but you would remove the actual internal wastegate and put that at the end of the passage to control boost.

 

[No_Skillz]

You have two option when running an external wastegate. Before the turbo, or after the turbo. You only weld shut the flapper hole when you are running a wastegate before the turbo (on the manifold). This is due to the fact that the wastegate controls the amount of boost by letting exhaust gas escape a different way than through the turbo's fins. If your wastegate is before the turbo, the gasses are already escaping via the wastegate and out through a dump tube (or custom recirculation to your downpipe) so there is no longer a need for the wastegate flapper hole.

If you are running an external gate after the turbo (on the O2 housing), you will still need that hole but not the flapper, since that is the passage where the external wastegate lets the exhaust gasses escape. However, you will need to weld shut the small hole where the flapper arm of the internal wastegate originally passed through, since you want to seal the turbine side from the wastegate side.

The main reason for switching to external gate is for those running large turbos and want the best exhaust flow possible without the turbulence caused by recirculation. Some also switch to control boost creep (but in my opinion they're just creeping because they haven't turned the boost high enough ).

 

[kylush]

Ok then.... but basically everyone that is running the gate on the manifold and an open dump has a custom dumptube and downpipe made..... or i would have to have a custom O2 housing made to bolt up to my current dp right... Because all the O2 housings i can find are for a recired dump tube, or for having the gate after the turbine...


Here is the turbo I'm planning on upgrading to...

EXTREME PSI : Your #1 Source for In Stock Performance Parts - Precision T & E SCM5031R Ball Bearing Turbocharger : Mitsubishi Eclipse 90-99 : (460 HP)

Edit* I am an idiot, I forgot to add the link and then when I looked it up I noticed that you can order it specially for an O2 mounted wastegate! So that should have all the passages needed for that setup right?

Also, not sure if i should even ask this here or start a new thread since it's kinda going OT in my own thread but how much boost do you think you could run through that with the stock IC?

 

[No_Skillz]

Yes, either option for wastegate on that turbo either plugs the wastegate hole or leaves it open accordingly.

Stock sidemount IC is not good for much boost over stock. You will need to upgrade to see any benefit from the larger turbo. I would say ~10psi on the 5031RE is reasonable for now.

 

[kylush]

Sweet! Thanks for the help dude

As far as the IC... looks like i'm gonna be spending even more money.... but it should be worth it!

Good thing I have about 4k to throw at this car...

 

[gstjeff11]

Hey if your looking for a new intercooler set-up, my friend runs pricematchedparts.com hit him up. they have some of the best prices around.