Internal Wastegate Hole Porting - HOW TO W/PICTURES

[Swinger13]

I originally read the sticky thread on IWG GT turbo's creeping like hell by @Lex; and how notorious these turbo's are for creep with an IWG set up. One of the solutions is porting the wastegate hole so I decided to snap some great iphone pics and show you guys how to do it.

I intend this thread to be possibly a STICKY; if not then I'm sure it'll be useful to some people.

I will make this thread in MULTIPLE POSTS so I can use all necessary picture I have taken.





So the subject being used is a GT28.

List of tools needed:

- Dremel tool or a drill
- tungsten carbide grinding bits
- sanding bit(s) or the flap sander bit style?
- a magnetic dish to keep all the bolts and what not in one safe place
- a vice (to hold the hotside steady while porting)
- safety glasses
- magic marker/sharpie
- needle nose pliers
- shop vacuum and/or compressor
- 13mm wrench
- protective gloves of your choice (if you don't like getting metal slivers in your hands)


So the first step is to disconnect the wastegate actuator arm from the flapper (circled in red).

I used needle nose pliers to remove the horse shoe shaped clip off by opening the pliers in the middle of the clip spreading the ends of it.

NOTE: Be EXTREMELY careful when removing this clip because for me it popped off and sprung into the abyss and I was shitting my pants until I luckily found it on the floor of my garage. I would recommend getting a finger on the clip while you take it off or cover it with something to prevent it from popping off and losing it.

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Next we remove the turbine housing.

There are 6 bolts that hold the turbine housing on (2 of which are circled in red). Use the 13mm wrench to remove these bolts. Once all the bolts and retainer plates have been removed, the turbine housing is free to pull off now. For easier access, you can remove the coolant and oil feed bolts/washers.

After you remove the turbine housing. The parts you should have now are:

- 2 retainer plates
- 6 turbine housing bolts
- WG actuator arm clip
- coolant and oil feed bolts/washers

NOTE: The oil drain under the red circle on the left will get in the way when threading the bolts out. Just loosen all the bolts down a little first then the turbine housing is free to clock (turn) whichever way you want giving free access to all the bolts (the same goes with re-installation).

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[Swinger13]

Next on the agenda is well...porting. Now I have never done this till now and if you're taking this on for the first time DO NOT be discouraged. This was one of the easiest projects I have done for my car, just a little time consuming. Just don't over do it. Port enough so that there will be a good improvement in flow but only go as far as you're comfortable doing. Make ABSOLUTE sure that you do NOT grind on the surface the flapper door sits on; the flapper needs a flat, clean surface to seal on.

The job for porting is make the WG hole better flowing so to do this you:

- make the hole bigger
- improve the flow path to the hole

There was not much grinding needed around the hole really, just a little bit. A lot of the removal was to make a better flow path the WG hole. This is where we start using the tungsten carbide bits.
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First I marked the outline of the flapper with some quick dry spray paint, wiped off any excess, let it dry, and placed in a vice with some cardboard padding. From the edge of the flapper to the edge of the hole is 1/8" inches so little removal there.

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In this picture you can see the obstruction outlined in red that will be smoothed out/grinded down.
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In the flow path; I removed a lot of the wall leading up to the wastegate (the red lines in the picture). The yellow grid in the picture is an area I would try to stay away from. Firstly the flow there is not bad in regards to the WG hole. Secondly, directly under that area is a one of the bolt holes that the turbine housing bolts sits in (finger pointing at it). This picture was the finished product. Basically before porting I could not see the WG flapper looking straight in; after porting, now I can see the WG flapper.
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Once you feel like your porting job is done and will provide sufficient flow to the wastegate, now smooth out all the work you've done with a sanding bit or sand paper (no pictures needed for this one (I hope)).




Lastly, re-assembly.

Basically it's reverse order of how you put everything on. To make it easy on me, I threaded in the turbo studs (5) that bolt to the down pipe and used them as legs to sit on. This way the retainer plates would sit in place by itself while I thread in the six turbine housing bolts. When putting the turbine housing back on. Thread down all 6 bolts almost all the way so there is still play in the retainer plates, clock your turbo to your desired position, then tighten the bolts with the 13 mm wrench. Set the wastegate arm back on the flapper, push the lock pin back on and WALLA, you are done!!!

Any questions/comments/feedback give me a shout or post

[triphop631]

Thanks...I am being a puss about doing this.
@8.5MS3;

Sent from my DROID RAZR using Tapatalk 2

[kritz]

Mike, let me at it! You know that I loves to remove metal from anything on a Mazda.

[8.5MS3]

lets do it today

[Swinger13]

Originally Posted by 8.5MS3 lets do it today

Just be careful with that clip that holds the WG arm on. Good luck!

Originally Posted by triphop631 Thanks...I am being a puss about doing this. @8.5MS3; Sent from my DROID RAZR using Tapatalk 2

It can be discouraging when you wanna work on a 1500 piece if POWAAA. Hopefully this thread will give people the courage to tackle it on.

[Swinger13]

If there's any additions/edits that people would like to see let me know and I'll change what's needed.

ALSO, I tried getting a hold of the clip that holds on to the wastegate arm and it works by holding it and prying it off with the needle nose pliers. This should help you guys more.

[86AmishMs3]

I would suggest no one use a dremel...will take forever. If you don't have airtools in your garage...you should.

[Swinger13]

Originally Posted by 86azms3 I would suggest no one use a dremel...will take forever. If you don't have airtools in your garage...you should.

I used a drill. Found I had better grip with it which made it easier to hold in place.

[maisonvi]

About how long did it take?

[Swinger13]

Originally Posted by maisonvi About how long did it take?

Being careful and being very maticulous as I am that way, it was like 2-3 hours. 2 hours should be plenty I would say. I work slow usually.

EDIT: I would say a good amount of the time was planning out where I should be porting so I didn't screw it up. I also would say you dont have to port anything past the wastegate hole because the purpose of this is to prevent as much creep as possible and not improve flow to the turbine wheel.

[mr.speedy3]

Bringing back from the graveyard! thanks for this writeup, and thanks for @86AmishMs3 for getting me to man up and doing this.

Safety First!
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Port job. Turbo is a GTX3076r. New engine going in tonight/this weekend. Will update on my boost creep.. Will most likely port again. But I am satisfied with the results for never doing this before. Grinding away pieces on an expensive part isn't as scary when you have beer.. haha

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For anyone considering this, you may consider placing alignment marks on the turbo before disassemble.

Another note, with my ATP kit from edge, apparently one of the bolts that hold the bracket to the turbo has a flatter head than the rest. I didn't know this when I put it back together. This bolt goes on the top so the stock oil feed line has clearance. If you don't use this the bolt for the oil feed will be crooked and not fit.

[BuddySpeed3]

How well did this procedure reduce boost creep in colder months? I have a bnr s4 that holds a perfect 18 psi across the board at spring pressure in the summer. In the colder months it hits 20 then creeps up to 24 psi at 0 wgdc. Also, where can I get me some of them tungsten carbide bits? Specifically ones made for turbine housings. Are these turbine housings cast iron?
Thanks I appreciate!