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Civic VX
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Discussion Starter #1
Turbine housing will likely not be used in my application so why not test my porting hand at it?

I really wanted to do the Corky Bell method (with the ditch and all) but unfortunately I couldn't find any pics of it. Even the DIY thread on here has since been de pictured :(

Trial and error it is!!!

I tried to do this, which is text from the Corky Bell method.
"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."

But my WG actuator is built in to the cover, so I cant scribe all the way around the flapper.

Here is what I did.
Went over to my valve lapping tools and grabbed some Prussian Blue. Put a nice thin layer on the flapper face and while holding the flapper arm back I installed the WG cover and bolts. I then opened and closed the flapper, and slid it side to side and really exercised every bit of play the flapper valve had.




This is pretty much the opposite of what is recommended by Bell. But there is a method to the madness. Using a dial gauge I measured the maximum play in the actual flapper valve. I then used this number and subtracted in from the edge line of the Prussian Blue, giving myself some play room for error. I then scribed my circle and did the Prussian Blue method again to check my work. Once satisfied I started grinding. The pictures tell the rest.





Thoughts?
 

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Classic Man
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Thats not really what you are supposed to do.

You are supposed to shape the inside of the turbine housing to direct flow more readily to the port.

You might get some unintended waste gate bypass now, but then again maybe not. That = slower spool, less power. Basically a pre turbo exhaust leak.
 

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as long as you didn't go too small, and it seems like you didn't then you should be okay. one thing this will do though is lower the effective pressure that it opens. more area on the valve will force the wastegate open sooner. it would also be a good idea to do a bit of reshaping so that there isn't a sharp edge leading to the wategate.
 

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Discussion Starter #4
So, even if I removed too much material from the seating surface, the goal would be to smooth the radius from the manifold flange to the seating surface?
 

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Classic Man
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I dont see that you've done anything that will have a negative impact. It just looks as if you need to finish the job. Open and smooth the transition from the backside and you're good... IMO.
I didnt even think about what FirstEG said, which is a super good call. More surface area exposed to manifold pressure = more force for WG to hold shut = more chance of leaks.
 

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You would only need this if you were having a boost creep problem. Thats pretty unlikely in a street car unless you have a massive turbo and are doing long high speed runs.

So i would say what you did there is a fine soltution to a boost creep problem, but its one most people here wont need.
 
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