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Cross-section of N9Txx head


Johnny

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I took the time to cut apart a scrap-head that I have, it got quite a beating before I was done <_<

post-114-1242670756.jpgpost-114-1242670764.jpgpost-114-1242670778.jpg

The pictures are from the first cylinder.

Those are faily good size ports for a small engine, the contours are well blended with a minimum amount of steps in them or sharp turns or corners . Should be able to make pretty good power without porting them.

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At first I'll probably just smooth out all the sharpe edges on the ports, just to get it running before the end of time.

Later I was thinking something like this:

Intake, raise the roof a bit, add J-B weld to the bottom, make the small radius smooth and as large as possible and smooth out all the sharpe edges. And look more deeply into getting the correct cross section area and mean velocities for the intended rpm. I think I have a basic understanding of how that works, but I need to study that a bit more. How does that sound?

I haven't found much info about cross section area for exhaust yet so I'll probably just smooth it out as best I can.

Mayby some of you guys have the expertise?

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At first I'll probably just smooth out all the sharpe edges on the ports, just to get it running before the end of time.

Later I was thinking something like this:

Intake, raise the roof a bit, add J-B weld to the bottom, make the small radius smooth and as large as possible and smooth out all the sharpe edges. And look more deeply into getting the correct cross section area and mean velocities for the intended rpm. I think I have a basic understanding of how that works, but I need to study that a bit more. How does that sound?

I haven't found much info about cross section area for exhaust yet so I'll probably just smooth it out as best I can.

Mayby some of you guys have the expertise?

Worked on engines in my military days. There was always a theory that you didn't want the intake ports to be too smooth as a little rough helped with turbulence.

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Yes, Intake side some roughness is needed to have small surface turbulance to help better air mixture to fuel. Like sandblasting kind of surface is good. Exhoust side should be polished good.

V-M

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