External wastegate 02 mounted w/31mm flapper?

[firebirdvert305]

Has this ever been suscessfully completed? I have an Evo 3 16g and im having a real hard time dealing with boost creep. I originally planned to run high boost with it, hence why I opted for the 31mm flapper option, but I cannot get it below 26psi before redline, it will creep that much. Im curious to know about people who mount on the 02 housings (which im sort of against) did they port out the wastegate flapper hole? I really want to plumb back the exhaust gases back into the exhaust, i dont like the sound of an externally dumped wastegate, which is another reason why im leaning towards mounting this wastegate on the 02. Plus it looks alot cleaner and no cutting or welding will need to be required. Im open to suggestions on maybe which would be the cheapest and most effective way to go?

 

[GVR4592]

I'm sure you've probably heard it before, but if it's ported properly it won't creep. Have you done any porting?

 

[firebirdvert305]

The car has always crept, it has 3" exhaust no cat, no muffler, just straight thru exhaust. It was ported by FP. I think external is my only resort to solve it, and or methanol injection and just eat it.

 

[GVR4592]

This seems to be a common misconception, porting will cure the problem if it's done correctly.

 

[daren_p]

The car has always crept, it has 3" exhaust no cat, no muffler, just straight thru exhaust. It was ported by FP. I think external is my only resort to solve it, and or methanol injection and just eat it.

Porting done by vendors is usually just turbine inlet to remove the step & sometimes turbine outlet, both of which do absolutely nothing as far as boost creep is concerned. If you want to get rid of the creep you will need to port it yourself. I have properly ported several evoIII turbos & they can all hold 14psi without creep & some were on straight through 3" exhausts. If you looks straight down the turbine inlet you need to remove additional material above the WG enterance so it is atleast parallel with the bottom lip as there is an overhang from factory. Depending on how bad the creep you may have to remove more material so the bottom sticks out further then the top. Another area to concentrate on is the divider wall on the outlet side of the WG flapper. If you look at where the exhaust will tend to flow through the WG hole you will see it runs right into the bottom corner of the divider wal which has a big jet out which will block alot of flow. Some grind this right off while I just made it smaller & angled the wall for a smooth exhaust path instead of hitting a flat wall. Depending on which O2 housing you are running you can open up the stocker a good amount on the WG side. There is a tech article on here which covers most of this.

What do you call high boost, I have run 22psi on mine with the 34mm flapper & it holds with the internal. If your going to run an external off the O2 housing you will more then likely run into the same creep issue. To prevent the creep even with an external you will have to do the above porting & enlarge the WG hole as well.

 

[DSM90AWD]

The car has always crept, it has 3" exhaust no cat, no muffler, just straight thru exhaust. It was ported by FP. I think external is my only resort to solve it, and or methanol injection and just eat it.

Properly porting will solve most of the problems out there, but the more open the exhaust is, the worse the creeping will be. As said above, I highly doubt any vendor would actually port the inlet to the WG passage, instead just mill the "step" on the inlet and possible "bell-shape" the outlet to match the gasket.

I ended up going with a Tial44 off my O2 housing (SBR modified an old VP O2 dump I had in my parts bin) and with the proper porting of the WG passage inlet, I've rock-solid boost control no matter what I set it at. I also get quicker spool as the external is much quicker to respond.

Nice thing is that I can use this on any future upgrade using a Mitsu housing, or if decide on a FP30/35XX turbo, already have the external to go with it