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Discussion Starter #1
This is a good guide written by Corky Bell (Author of Maximum Boost).
Many people in the miata community send their IWG turbos to him to have them ported, which shows a dramatic improvement in boost control and largely eliminated boost creep.
This is exactly what he does to the turbos and has made it available to us all for free. Pretty generous, eh?

BEGi - - Corky's Comments - turbo_porting

Corky Bell said:
Disclaimer: Do this at your own risk. BEGi extends no warranty nor accepts liability to any modifications performed.

Tools required:
Die grinder
Carbide rotary cutter
Stone rotary grinder


Enlarging the Wastegate Port:

1. Remove the turbo from the car and set it on a table. Remove the cir-clip ("C" or "E" clip) from the actuator push rod. Remove the turbine housing from the C.H.R.A. (center section of the turbo).

2. Note that the wastegate valve (flapper door) can move around quite a bit. This freedom of motion causes a problem with enlarging the port. The hole cannot be uniformly larger as the free motion of the valve can cause the edge of the valve closest to the pivot arm to collide with the edge of the hole and jam it open. The area below the pivot arm, attached to flapper door, must remain unchanged. This segment is about .50 long. Refer to the picture below.  



3. With a marker or a sharp pointed scribe, mark the housing casting around the edge of the valve while pushing the valve away from the marker. This will establish the minimum area the valve can cover in all positions.



4. With the valve tilted out of the way, mark a semi-circle about .100 inside the line already established. This will be the edge of the porting that can be done.

Again, do not touch the edge of the original port as described above.

This is what is should like like when done. Make note of the Oval Shape!




Creating a channel on the Turbine Inlet Casting:

While looking into the inlet of the wastegate housing, imagine a ditch dug to the port that "channels" the exhaust gas toward the port. This channel gets deeper as it approaches the port. It should get to a depth that leaves about 1/8 inch of material between the bottom of the ditch and the valve seat at the other side of the port.

The stone grinder is better suited to remove material in the channel.



With the remaining 1/8 inch thickness, round off the edge into the port.

Clean thoroughly and re-assemble.


Call Corky at 830-438-2890 if you need assistance.

This article was published on Saturday 03 April, 2010.
 

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Discussion Starter #5
yah, I know most of us are running EWG now, but hopefully this will help someone someday (given that they use the search button....)
 

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Pew Pew!
EJ6
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I remember reading about this some where before. Good info. Rep for sharing =)

Edit:...Cant, gots ta spread'em first.
 

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might come in handy thanks!
-Luke
 
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