port polished head... who what where when why how?

[nonovurbizniz]

but polishing can cause TOO smooth flow giving worse air/fuel mixing capabilities...

Also misted fuel sticks to smooth surfaces... where the roughness in casting stirs up the air against the walls so the fuel doesn't really have a chance to stick (as it's being blown of as air bounces off the rough-edged wall.)

If you spray whatever onto both a polished surface and a rough casted surface you'll notice the cast surface prevents it from pooling and becoming a liquid again... where the polished smooth surface allows all of the tiny droplets of water to re-connect and become more of a "puddle".