Extrude Hone vs Hand Porting and Intake



Extrude Hone vs Hand Porting

I see people posting in forums asking about how the Extrude Hone process differs from hand porting, so I thought I would write this short write up on my experience and others with the results of using this process.

In the extrude hone process, the intake/head is connected to a rig that hydraulically forces a putty like substance which has abrasives in it through the ports to remove material from a casting. It removes material from the areas that pass putty the fastest and remove much less where material moves more slowly. As such, it has been described as a “dumb” process because it does not selectively remove material to re-shape the port/runner to give better average flow throughout the runner instead of just where putty flow was fastest. Here is a post by Darin Morgan, who was the head of R&D at Reher-Morrison Race Engines, recognized as an authority on porting.

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As he mentions, If you want to use EH, use it for something like an upper intake that you do not wish to pay to have cut open to hand port – but don’t expect big gains from the process as it does not remove a lot of material. I’ve had EH pieces come across my bench for many years and I have seen how either not enough material was taken out in eareas you want it removed from, or too much was removed from an area you did not.

Here is a shot of an Explorer upper intake from 2006 that had the EH process run on it. you can see that it did not remove all the casting flash from the runner and the putty split leaving two paths of indention in the runner.

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In this carb intake, the process removed too much material and actually broke through the casting in the short side of the runner – it is back lighted and the hole is clearly visible. So much for Quality Control after the process is done – the owner did not know this had happened.

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Here is a RPM1 runner exit that shows the bias of material removal from the lower portion of the runner which further demonstrates it’s inability to control the cut.

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The following pictures I put together side-by-side to show what the runner interiors look like when comparing a EH porting with our hand ported lower. You can see the material left in the upper half of the runner and how in one, the port exit had actually been shifted slightly to the short side by the abrasive cutting more on that side.

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If you do get the EH process done to your intake or heads, I highly recommend you get them flow tested by a third party to verify you received the value and flow you were told – see the below post from Yellow .

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You can see, that I and others have a bias and it is not just because we are hand porters – if I was to pay as much money as the EH process charges, I would expect better results than hand porting or the same as a bare minimum. This has not proven to be the case from my perspective.

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