Smooth vs. rough surfaces
Nov 12, 2007, 12:05 PM
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Smooth vs. rough surfaces
I have heard both sides of the argument. And most people bring up vaild points to their sides.
If your intake pipe, TB, and intake manifold were completely deburred and polished smooth or deburred and the surface is left rough, which choice would yield a higher flow?
To throw a curveball in the mix. Would a dimpled pattern (similar to that on a golf ball) yield a higher flow?
I am curious to hear your thoughts.
If your intake pipe, TB, and intake manifold were completely deburred and polished smooth or deburred and the surface is left rough, which choice would yield a higher flow?
To throw a curveball in the mix. Would a dimpled pattern (similar to that on a golf ball) yield a higher flow?
I am curious to hear your thoughts.
Nov 12, 2007, 12:09 PM
#2
dimpled flow yields a higher flow velocity. due to the dimples allowing a vortex of air that acts like a buffer between the walls and the airstream.
with completely polished and deburred there will be more friction where the air rubs against the walls, making for a slower flow velocity.
with completely polished and deburred there will be more friction where the air rubs against the walls, making for a slower flow velocity.
Nov 12, 2007, 12:56 PM
#4
dimpled flow yields a higher flow velocity. due to the dimples allowing a vortex of air that acts like a buffer between the walls and the airstream.
with completely polished and deburred there will be more friction where the air rubs against the walls, making for a slower flow velocity.
with completely polished and deburred there will be more friction where the air rubs against the walls, making for a slower flow velocity.
In general, the smoother the surface, the less flow resistance. You do not want a dimpled surface on a straight section of pipe or a flat surface. Where you want dimples is in the inside of a bend on internal flow.
The dimples effectively increase the turbulence of the flow at the boundry layer giving it more 'momentum'. This allows it to better follow curves, i.e. prevents flow separation. And that is why golf ***** are dimpled.
If you could have it both ways, have it smooth everywhere except the inside of bends. If you can only have one way, I'd go smooth.
Nov 12, 2007, 01:56 PM
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Reposted from the less successful thread in advanced:
If it were me, on a modern engine, I would prefer a smooth surface. Considering the fuel is added a relatively short distance from the valve, with a good injector that atomizes well, I don't think the surface needs to be as rough as on a carbureted V8, where the fuel and air have to stay mixed all the way down the intake runners and into the ports. But that's just from what I've heard in the past and what makes sense in my head. There are other people smarter than me that could probably add some more and go into your dimple idea.
The smarter people than me includes anyone who has an understanding of the boundary layer concept.
If it were me, on a modern engine, I would prefer a smooth surface. Considering the fuel is added a relatively short distance from the valve, with a good injector that atomizes well, I don't think the surface needs to be as rough as on a carbureted V8, where the fuel and air have to stay mixed all the way down the intake runners and into the ports. But that's just from what I've heard in the past and what makes sense in my head. There are other people smarter than me that could probably add some more and go into your dimple idea.
The smarter people than me includes anyone who has an understanding of the boundary layer concept.
