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I am just wondering I have been seeing pics of the design of the SR20DET head and the exhaust ports narrow considerably from the chambers to the exit ports? How come this is, is there a purpose behind it, and if ported and polished could that narrow spot be grinded to the same circumference as in the chamber? and if so would the exhaust manifold still seal with a oem gasket? Thanks
 

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I am just wondering I have been seeing pics of the design of the SR20DET head and the exhaust ports narrow considerably from the chambers to the exit ports? How come this is, is there a purpose behind it, and if ported and polished could that narrow spot be grinded to the same circumference as in the chamber? and if so would the exhaust manifold still seal with a oem gasket? Thanks
The reason the exhaust port narrows is that they designed the volume at any given point in the port to be the same as at any other point. Right at the cylinder, much of the volume of the port is being displaced by the valve and valve stem, but after the port turns and the stem no longer takes up volume, they decreased the size of the port most likely for better flow and packaging.

Head porting is best done by professionals who have done CFD analysis on it to see what would best improve airflow.
 

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Thanks man, yea I was planning on having it done by professionals I just wanted to know ahead of time what to expect.
 
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