How to run or set up external wastegate

[spooln4fun]

I got a t28 with an internal gate. I am wanting to get rid of that and run an external gate, I know a new o2 housing is needed in order for this work, along with the wastegate. What will i need to do with the internal wastegate thats built on the turbo its self? Is this possible? or will i just have to buy a new turbo and whole new set up

 

[4g63Powered]

If you want to use your T25 for some reason, you'll have to either:

a.) Weld the flapper shut and put a wastegate provision on your manifold or buy a new manifold

-or-

b.)remove the flapper, weld the 'pivot' hole shut, and buy a wastegate and a new o2 housing that will mount the wastegate.

 

[99gst_racer]

You'll have to modify your existing turbine housing no matter what.

Are you planning to mount the external gate on the manifold or the O2 housing?

 

[mtshores]

I would just buy a new manifold that had an external gate flange. It seems easier that way to me, and also if you plan to upgrade your turbo any time this should help spool or at very least look cooler than the old cast iron mani. I personally have a DN Performance manifold with a 44mm wg off of it. This manifold has worked very well for about 3 years and its had 2 big turbos hooked to it. I have stuck with the stock 02 housing just had it ported. If you were not going to do the work yourself an 02 mounted wg might be a little easier to put on and save some install $, but if you were going to do it all yourself than I would do the upgrade manifold. I think the long term benefits of doing an upgraded manifold would need to be factored into your decision.

 

[spooln4fun]

Well I will be keeping my manifold since I just bought the FP Race mani. I would be running the wastegate off the o2 housing.

What I got from everyone is if running it off the o2 housing which I am i just need to have my wastegate on the turbo taken off and the flapper hole welded shut and once I get the new o2 housing and my gate on everything will be back to running?

 

[No_Skillz]

What I got from everyone is if running it off the o2 housing which I am i just need to have my wastegate on the turbo taken off and the flapper hole welded shut and once I get the new o2 housing and my gate on everything will be back to running?

Not quite.

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.

Most members on here would say that an external wastegate for the t-28 is not necessary. It's a small turbo and you will gain no advantage by switching to external gate. 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 ).

 

[vanilla gorilla]

I bought an SBR cast manifold and bolted my TiAL 38mm wastegate to it. I took off the turbo and welded the stock internal wastegate flapper closed. I made an external dump tube for my wastegate. Running stock o2 housing.

 

[99gst_racer]

What I got from everyone is if running it off the o2 housing which I am i just need to have my wastegate on the turbo taken off and the flapper hole welded shut and once I get the new o2 housing and my gate on everything will be back to running?

You'll also need to enlarge the wastegate passage in the turbine housing so that more exhaust can flow to the external gate.

 

[spooln4fun]

Thanks so much for all the info. Prob going to take a look in to this